c10 cruise control diagram

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Welcome to our knowledge base of totally random stuff relating to GM 1983- forward 'square body' truck cruise control.

Functionality.

Note that this article is only for the 1983 forward Custom Cruise III systems on the 'square body' style trucks. 1988 and forward newer body style trucks used a different system.

The system consists of a mode control assembly, electronic controller (module), Vehicle Speed Sensor (VSS) buffer amplifier, servo unit, and release switches and valves. The servo unit maintains vehicle speed (throttle position) by trapping vacuum in its diaphragm chamber at servo positions determined by the control module. The module monitors mode control switch position, signals from the VSS buffer amplifier, servo position and release switch operation, then operates vacuum valves within the servo unit to control servo operation and vehicle speed. The module also contains a speed limiting function which prevents system operation at speeds below approximately 25 m.p.h..

The mode control assembly consists of a 3 position slide-type switch and a set/coast switch button. To operate the system, the slide switch must be in on position and vehicle speed must be above 25 m.p.h.. The system is engaged at the desired speed by fully depressing, then releasing the set/coast button. Cruise speed can be increased from set position by accelerating vehicle to desired speed, then pressing and releasing button. In order to decrease speed, the set/coast button is held in the fully depressed position (disengaging system), then released when the desired speed is reached. The system can be disengaged at any time by depressing the brake or clutch pedal, or by moving the slide switch to off position.

If the system is disengaged by depressing the brake or clutch pedal, the last set speed will be retained in the module memory until the slide switch or ignition switch is moved to off position. Momentarily moving the slide switch to the resume/accel. position will cause the vehicle to accelerate to the last set speed and maintain that speed. If the slide switch is held in the resume/accel. position, the vehicle will continue to accelerate until the switch is released. When the switch is released, the speed that the vehicle accelerated to becomes the new set speed.

The slide switch also allows a 'tap-up' function to increase cruise set speed in 1 m.p.h. increments. With the cruise control engaged and operating, 'tapping-up' is done by pressing the slide switch to the resume position, then quickly releasing it. This procedure can be repeated 10 times before the system must be reset to a new speed in the conventional manner.

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Component operation

Troubleshooting

Of note for general troubleshooting if none of the fuctions work, or if there is intermittent function: a common failure point is the wire from the control stalk where it passes into the steering column from the stalk. As the stalk is moved, the wire can be pinched over and over if it falls into the wrong position. This can lead to eventual wire separation and failure.

Disengagement switch

The brake disengagement switch is attached to the brake pedal bracket. It provides both an electrical and vacuum signal for cruise control function. The electrical contacts of the switch are closed when the brake pedal is not depressed, and the vacuum vent is closed. When the pedal is depressed, the electrical switch contacts open and the vacuum line is vented to atmosphere. This venting of the diaphragm of the control unit results in the diaphragm being released and all throttle control by the unit instantly ends regardless of electrical inputs.

It is a very simple mechanism. The vacuum portion merely has a plunger with an o-ring seal attached, which moves into the closed position along with the plunger depression. The electrical side is attached to the same plunger and engages the continuity between contacts when the plunger is depressed. An internal spring keeps the plunger loaded against the brake pedal to follow its travel. The at-rest position of the plunger is fully depressed, which corresponds to when the brake pedal is not depressed. I.e., when the brake pedal is not pressed down, the plunger is fully depressed within the switch, the electrical contacts are engaged, and the vacuum vent is closed.

The switch is both easily checked, and sometimes easily repaired. Both functions can be easily checked with a vacuum gauge and and meter. If the vacuum side is defective and no mechanical damage is not evident, the o-ring is easily replaceable. The electrical contacts can also wear over time, which provides a loss of continuity, or a temporary loss at times which can disengage the cruise contral erroneously. This my be able to be fixed by slightly and gently bending the contacts closer to center, or widening the connection bridge on the plunger slightly to account for wear.

Control stalk

The control stalk on the left side of the steering column consists of a slider switch and a NO (Normally Open) button. The slider switch has positions for 'off', 'on', and a momentary position for 'resume/accel'. Four wires run from the switch assembly on the end of the stalk into the steering column and join a plug above the brake pedal.

The tests for the switch assembly are straightforward, and are listed in the troubleshooting section. However, of note is the potential wire pinch-point where it enters the steering column. There is sometimes a slot in the upper casing of the directional/high beam switch which is intended to hold this wire back away from the pinch-points created by the lever movement. If the wire comes free or is not installed correctly, the wires can be pinched and, over time, frayed. If one of the four wires to the switch is found to have no continuity, or the switch shows no or intermittent funtion, this could be the reason.

This early type can be interchanged with the later type, or just the 'spray' switch portion may be changed. If just the 'spray' activator is changed, the old stalk must have a hole drilled in the plastic portion for the wire to pass through as seen in the photo below.

Continuity can easily be checked by accessing the lower plug at the bottom of the steering column above the brake pedal. Then the switch assembly can be pushed out from the end of the stalk enough for checking purposes. Dissassembly is accomplished by carefully prying off the end cap of the stalk with a sharp knife blade, being careful not to use too much pressure and damage or break the plastic. Once loose, the cap and end button may be pulled free. Gently work some slack in the wire where it joins the steering column, and carefully pull the switch assembly from the end of the lever.

If the switch assembly itself is bad, it can easily be un-soldered and a replacement soldered in. The switch and stalk may then be put back together. This prevents the pain and suffering of replacing the entire stalk and wire, which runs down through the steering column.

If the wire is found to be compromised at the column entry point, there is usually enough slack in the wire length to pull the wire out and shorten it the three inches or so up to that break point. If this is not possible, the entire wire must be removed from the steering column which is far less easy to do.

A: 12v+ power is routed to the stalk by the 'A' leg. This leg should always have 12v+ power when ignition is in 'Run'. B: Once the switch is 'On', 12v+ is supplied to the 'B' leg of the switch outut which controls the 'Brake input' circuit and gives the control module a signal that it has been switched on (the 'On/Off' input). If any part of the 'Brake input' leg is broken through their component switches, the module will deactivate the cruise control. If the unit is switched 'Off', the module will deactivate the cruise control. C: Once the switch is 'On', 12v+ is supplied to the 'C' leg of the switch outut which controls the 'Resume/Accel' input. This circuit will only send 12v+ to the module when the momentary switch is depressed. D: Once the switch is 'On', 12v+ is supplied to the 'D' leg of the switch outut which controls the 'Set/Coast' input. this circuit will only send 12v+ to the module when the 'Set/Coast' momentary switch is depressed.

The module has one normally open valve and one normally closed valve, controlled by solenoid coils. These valves regulate the vaccum inside the chamber that is connected to the throttle. As vacuum is applied, the throttle is opened. As vaccum is released, the throttle is closed. A third coil is an inductance feedback for the module so that it knows the present position of the throttle and diaphragm, and can adjust according to the current desired speed/position.

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• Your sub-harness should have White and Purple wires on the Brake switch connector.
• Add a wire teed into the wire on Terminal A of the Cruise module. I would match the wire color to the existing Terminal A wire.
• The White terminal G wire needs to tee into the stop lamp wire between the brake pedal switch and the column.
• The Cruise Release circuit should run in series from the wire you just teed or wyed into cruise module Terminal A, through the brake and clutch pedal and cruise control cutout switches, to the Purple wire on "Cruise Release" terminal D. Put the Purple wire on one switch and the extra Terminal A wire on the other with a Jumper running from switch to switch between the leftover terminals. If it's an automagic truck both the purple and Terminal A Tee wire goes to the cruise control brake pedal switch.
• When wired properly with the pedal or pedals up (switch contacts closed) you should measure 0 Ohms between D & A with the stalk unplugged and just the pedal switch or switches plugged in.
• Both manual and automatic pedal switch options are shown below.

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Chevrolet R-V 1989 Wiring Diagrams

• page of 143 Go / 143

Table of Contents

• Description
• Tracing Circuits
• Wire Coding
• Wiring Diagrams
• Circuit Controllers
• Circuit Diagnosis
• Fusible Link
• Abbreviation List
• Grounded Circuit
• Open Circuit
• Short Circuit
• Diagnostic Tools
• Powered Test Light
• Unpowered Test Light
• Circuit Maintenance and Repair
• Metrl-PACK CONNECTORS
• On-Vehicle Service
• Weather-Pack Connectors
• Twisted Wire Repair
• Twisted/Shielded Wire Repair
• Weather-Pack and Metri-Pack Connectors
• Wiring Repair
• Special Tools
• 1989 R/V Truck
• Fuse Block Detail
• Marker Lamps
• Hazard Lamps
• Throttle Body Injection
• Emission Controls

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• 1 Wiring Diagrams
• 2 Table of Contents
• 3 1989 R/V Truck
• 4 Fuse Block Detail
• 5 Throttle Body Injection
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Summary of Contents for Chevrolet R-V 1989

• Page 1 1989 WIRING DIAGRAMS R-V, P TRUCK MODELS When reference is made in this manual to a brand name, number, or specific tool, an equivalent product may be used in place of the recommended item All information, illustrations, and specifications contained in this manual are based on the latest product information available at the time of publication approval.
• Page 2 WIRING DIAGRAMS 2 DESCRIPTION WIRING DIAGRAMS All diagrams in this manual are based on the latest product information at the time of publication approval. The right is reserved to make changes at any time without notice. SUBJECT PAGE Description Tracing Circuits Baste Electric Circuits Circuit Diagnosis Abbreviation List...
• Page 3 WIRING DIAGRAMS 5 WIRING DIAGRAMS 6 path. For example the switch controlling the headlights is at the power end of the circuit while the door switch controlling the domelight completes the ground path. Relays are remotely controlled switches. They are used in high current circuits and in circuits controlled by sensors.
• Page 4 WIRING DIAGRAMS 7 WIRING DIAGRAMS 8 GROUNDED CIRCUIT(Figure 10) EFE—Early Fuel Evaporation PK—Park A ground circuit is like a short circuit but the current EGR—Exhaust Gas Recirculation PLR—Puller flows directly into a ground circuit that is not part of the ELEC—Electric PNKf-PInk original circuit.
• Page 5 WIRING DIAGRAMS 10 WIRING DIAGRAMS 9 DIAGNOSTIC TOOLS 50. Power Source VOLTMETER SCALE: 0 Volts through 15 Volts 51. Circuit Breaker 52. Switch (Closed) 40. Power Source A = 3 Volts 30. Power Source 53. Voltmeter 41. Circuit Breaker B = 7 Volts 31 Circuit Breaker 54.
• Page 6 WIRING DIAGRAMS 11 WIRING DIAGRAMS 12 Wiring harnesses are joined by using a multiple plug WIRE SIZE With the low current and voltage levels found in some and receptacle connector block, or a terminal post circuits, it is important that the best possible bond at all CONVERSION TABLE chassis junction block.
• Page 7 WIRING DIAGRAMS 13 WIRING DIAGRAMS 14 90. Jacket 91. Twisted Wires 92. Splice Clip 93. Crimp and Solder 94. Electrical Tape Wrap 95,. Outer Electrical Tape Wrap. B-06230 100. Jacket Figure 20 Twisted Wire Repair 101. Aluminum/Mylar Tape 102. Drain Wire 4.

Page 8: Special Tools

Page 9: table of contents.

• Page 17 R.H. HEADLAMP R.H. SIDE MARKER SWITCH SIDE MARKER LAMP LAMP 6294015 R.H. TAIL. STOP & DIRECTIONAL LAMP TO l/P ► CLUSTER 9 .8 BRN CONN. SPLICE 9 R.H. PARK LAMP BACKUP SHEET LAMP METAL GROUND SPLICE 150 LICENSE LAMP SPLICE 150 BACKUP LAMP 150 .8 BLK...
• Page 18 R.H. HEADLAMP WIDESIDE PICK-UP SIDE MARKER SWITCH R.H. (R05) ONLY LAMP SIDE MARKER LAMP 6294015 R.H. FRONT / ^ " T \ . REAR CLEARANCE U M i* CLEARANCE CLE / LAMP U— U LAMP 6294015 6294015 R.H. TAIL. STOP & DIRECTIONAL LAMP R.H.
• Page 22 FROM R.H SIDE MARKER LAMP FROM RH 150 8 BLK FRONT & REAR CLEARANCE LAMPS (RPO R05 ONLY) 19 8 DK GRN 8911029 T R.H. TAIL STOP & R.H. TAIL, STOP & DIRECTIONAL DIRECTIONAL LAMP LAMP (PART OF RH TAIL. STOP, DIRECTIONAL.
• Page 24 FRAME R.H. R.H. 12034372 SIDE MARKER GROUND SIDE MARKER LAMP R.H. LAMP — f iS ^ ----- 1 51 3.0 BLK HEADLAMP CONNECTOR SHEET E D n a g g y METAL t z f e 6294015 GROUND 151 .8 BLK 4 1 9 TO l/P CLUSTER...
• Page 25 SHEET 150 .8 BLK METAL GROUND FUSE BLOCK E D G) (5 H ffl IE E « « FROM SIDE R.H. TAIL, STOP & SPLICE 150 MARKER LAMP DIRECTIONAL (s s i a ® e e «oo 150 .8 BLK - LAM P G 3 (3 (3 G B Q D S D O B •A T T...
• Page 27 19 BLK- ■6-3.0 PPL- -33 .5 TAN/WHT- STARTER MOTOR SOLENOID d d i o 17^— --- TO PARK m p D BRAKE WARNING SW . JUNCTION Q □ 8911698 BLOCK Q D f a B u Q H l l/P CLUSTER CONN.
• Page 29 TO A/C COMP 15 .8 BLK l/P CLUSTER CONN. IGNITION L 2 5 - V 6 SECTION A - PAGE 21 FUSE BLOCK...
• Page 30 ELECTRONIC CONTROL MODULE CONNECTORS 9 S I G E N E R A TO R r----- 1 — p " ' ♦ ---- • I----------- \ |---- -— | > ----- h IGNITION LE8, L T 9 - V 8 SECTION A - PAGE 22...
• Page 31 CONVENIENCE CENTER TO BRAKE SWITCH (MD8 ONLY) l/P CLUSTER CONN. IGNITION L 0 5 , L 1 9 - V 8 REAR SECTION A - PAGE 23 FUSE BLOCK...
• Page 32 l/P CLUSTER CONN. GENERATOR IGNITION L 05 , L19 - V 8 REAR FUSE BLOCK SECTION A - PAGE 24...
• Page 33 OXYGEN 439 .8 PNK/BLK SENSOR 412-.8 PPL THROTTLE POSITION TO COOLANT SENSOR TEMP SENSOR 412 .8 PPL SPLICE 4 5 2 452 A ______ 452 .8 BLK 452 .8 BLK ELECTRONIC 417 .8 DK BLU 417-.8 DK BLU CONTROL MODULE |»5l| 1 416 .8 GRA •...
• Page 34 HOT FUEL HANDLING HOT FUEL HANDLING L 0 5 /L 1 9 —V8 SECTION A - PAGE 26...
• Page 40 FRAME GROUND AUX FAN COOLING SW FROM RH HEADLAMP(S) PARK & DIR SIGNAL > LAMPS SHEET METAL 151 3.0 BLK GROUND 702 2.0 BLK/RED< •935 .8 DK GRN — |9 3 5 39 .8 PNK/BLK — \ 2 j -2 -2 .0 RED------- AUXILIARY 12010015 COOLING...
• Page 43 RIGHT-HAND REAR SIDE DIVERT SOLENOID 150.8 BLK- ENGINE GROUND SPLICE 900 .8 YEL- 39 .8 PIMK/BLK. 39 .8 PNK/BLK - ENGINE SPLICE 900 ,rm I n— [ R 5I I5 9 1 900 .8 YEL 39 .8 PNK/BLK- AIR DIVERT SOLENOID 12040753 ( 3 0 | 1 31 l f 2 6 l l 3 6 H 9 7 l f 9 T | IGNITION SWITCH...
• Page 44 RIGHT-HAND DIVERT SOLENOID ENGINE ENGINE TO 4 GRD STRAP- GROUND BODY GRD 936 .8 YEL- ► TO “ SERVICE 39 .8 PNK/BLK. ENGINE SOON’ LAMP 39 .8 PNK/BLK SPLICE 936 936 .8 YEL- AIR DIVERT SOLENOID 12040753 IGNITION SWITCH CONTROLLER GROUND TACHOMETER TO COIL 39 .8 PNK/BLK-...
• Page 45 4 3 6 ENGINE GROUND ENGINE TO BODY RIGHT HAND -4-GRD STRAP. -436 .8 BRN- GROUND DIVERT ■900 .8 YEL- SOLENOID 12015792 I IP TO “ SERVICE ENGINE SOON’ -39 .8 PNK/BLK- LAMP 419-.8 BRN/WHT. DIRECT GROUND DIVERTER 900-.8 YEL-------- —...
• Page 46 MANIFOLD THROTTLE -439 .8 PNK/BLK ABSOLUTE POSITION PRESSURE SENSOR SENSOR 452-.8 BLK -440-1.0 ORN- 417 .8 DK BLU 416 .8 GRA — -455- 8 BLK ----- 455 .8 BLK ---- -432 .8 LT GRN 432 .8 LT GRN -417-.8 DK BLU- 417- 8 DK BLU 416-.8 GRA —...
• Page 47 -439 .8 PNK/BLK 439 .8 PNK/BLK ELECTRONIC CONTROL M O DULE-INPUTS L0 5 , L 1 9 - V 8 -439-.8 PNK/BLK SECTION A - PAGE 39...
• Page 48 ELECTRONIC SPARK TIMING E.V.R.V. FOR L05 W/H.D & L19 ENGINE ONLY SWITCH ELECTRONIC CONTROL MODULE L05, L19-V 8 SECTION A - PAGE 40...
• Page 49 ELECTRONIC CONTROL M O D U L E -O U T P U T S L 0 5 , L 1 9 -V 8 SECTION A - PAGE 41...
• Page 50 WIRE CIRCUIT WIRE CIRCUIT COLOR CAVITY DESCRIPTION COLOR CAVITY DESCRIPTION SIZE SIZE 4 6 5 DK GRN/WHT FUEL PUMP RELAY DRIVE NOT USED NOT USED 4 3 6 AIR SWITCH SOLENOID NOT USED 4 4 4 LT GRN/BLK STEPPER COIL B LOW 4 3 5 EGR SOLENOID 4 4 3...
• Page 51 CIRCUIT WIRE CIRCUIT WIRE COLOR CAVITY DESCRIPTION COLOR CAVITY DESCRIPTION SIZE SIZE 4 5 2 SYSTEM RETURN LT GRN M ANIFO LD ABSOLUTE PRESS 4 3 2 1 5 0 SYSTEM GROUND THROTTLE POSITION SW ITCH 4 1 7 DK BLU NOT USED CO O LANT TEMP.
• Page 55 ■422- 8 TAN/BLK • ■ 446- 8 LT BLU — STOP LAMP SWITCH (MD8 ONLY) TRANSMISSION ELECTRONIC CONVERTER CLUTCH CONTROL MODULE SOLENOID CONNECTORS ■ OPENS IN CLOSES WITH 4TH GEAR INC. TEMP. . 12047948 12010649 12010503 TO INST. CLUSTER SPLICE "...
• Page 56 422 .8 TAN/BLK- > 422 .8 TAN/BLK TRANSMISSION KICKDOWN L05 ONLY TO ECM SOLENOID L05/L19 ONLY SPLICE 422 ENGINE 55 .8 ORN- 422 .8 TAN/BLK L19 ONLY 422 .8 TAN/BLK 2984092 ----------39 .8 PNK/BLK £ 12047782 J 4 2 2 j 39 -—...
• Page 57 GROUND BLOWER SWITCH DIODE (NOT USED WITH LE8, LT9, L25I ‘ 899 .5 CAPAC JUNCTION AIR CONDITIONING (RPO C60) BLOCK SECTION A - PAGE 49...
• Page 58 BLOWER SWITCH 12004101 52-5.0 ORN •51-1.0 YEL- ■52-2.0 ORN- E S S l SPLICE 52 2977940 2977253 8900420 2977518 RESISTOR GROMMET 8911215 REAR BLOWER MOTOR GROUND ff) S ) (3 B (9 IB ID « « *■ 12004740 (3 d (5 B Q D 0 8 O D * °...
• Page 59 RESISTOR BLOWER MOTOR I M a H U tell 2965019 l l T sffil □ 2977976 GROMMET ■ o r 8911217 12004067 -5 2 -2 .0 ORN- 51-2.0 YEL- ■51-2.0 YEL— 50-2.0 BRN 50-2.0 BRN -5 2 -2 .0 ORN- ■52-2.0 ORN------ •72-2.0 LT BLU- —...
• Page 60 BLOWER SWITCH 51-2.0 YEL -952-2.0 DK GRN- GROMMET GROMMET 8905790 12004752 12015958 RESISTOR 1501 12004267 HOT IN \ r L BLOWER MOTOR AUXILIARY HEATER (RPO C36) SECTION A - PAGE 52...
• Page 61 ILLUM ILLUM ILLUM ILLUM ILLUM l/P CIRC U IT RO UTIN G HEATER W IT H T A C H O M E TE R A/C CONTROL ASSEMBLY W /O - l/P CIRC U IT RO UTIN G W /O W IT H O U T T A C H O M E TE R BRAKE FROM...
• Page 62 2 9 6 2 9 6 5 COOLANT TEMP SENDER COOLANT TEMP SENDER L05, L19. LT9,LE8, LH6,LL4 TO HOT FUEL HANDLING MODULE (L05. L19) TO CONVENIENCE CENTER TO BRAKE SWITCH (MD8) PRESSURE SENDER PRESSURE SENDER L19. L25, LE8, LH6, FUEL TANK SENDER L25.LE8,...
• Page 63 ILLUM ILLUM ILLUM ILLUM ILLUM l/P CIRCUIT ROUTING WITH TACHOMETER W /O-l/P CIRCUIT ROUTING WITHOUT TACHOMETER FROM W/S WIPER WASHER SW C 1 2 0 ) ■120-1.0 TAN/WHT- ELECTRIC FUEL PUMP -30 .8 PNK----------- FUEL GAGE SENDING UNIT 12059473 L05/L19 INSTRUMENT PANEL GAGES SECTION A - PAGE 55 BLU OR PPL OR LT.
• Page 64 TO GLOW PLUG RELAY & CONTROLLER----- TO AUTO INDICATOR LAMPS TRANS KICKDOWN SOLENOID SECTION A - PAGE 56 (M40)
• Page 65 l/P CIRCUIT ROUTING WITH TACHOMETER W /O-l/P CIRCUIT ROUTING WITHOUT TACHOMETER 419 .8 BRN/WHT 33- 5 TAN/WHT 33 .5 TAN/WHT IGNITION SWITCH J S i A 1 ! ; i j \ INDICATOR LAM PS ---- I 1 1 1 ’ ^ 1 8917693 SECTION A - PAGE 57 <...
• Page 66 ■39 .8 PIMK/BLK DIESEL ONLY FROM W/S WIPER WASHER SW FRONT REAR FUSE BLOCK SEAT BELT W ARNING BUZZER SECTION D -P A G E 6 4 SECTION A - PAGE 58...
• Page 67 f & l 1 ^ 1 Q D ncm c z j n i a iso j □E lnE ill O D D CLUSTER CONN. □E U I n n d l □ Q D llE H ] 8900371 -3 3 .5 TAN/WHT- |3 0 0 | IGN BAT 3 ____...
• Page 68 •141-.8 BRN/WHT 4-WD 141-.8 BRN/WHT- INDICATOR LAMP 6294974 -1 5 0 .8 BLK- — 150 .8 BLK- FRONT D A D GROUND FUSE BLOCK TRANSFER 150-.8 BLK CASE 156 .8 WHT ■ SWITCH 12004267 4-WD SHIFT ■150 .8 BLK- ■ n i LEVER LAMP >150 .8 BLK- V 1 0 0 ,2 0 0...
• Page 69 CRUISE CONTROL MODULE CRUISE VENT VALVE CRUISE CONTROL VAC SPEED SENSOR CRUISE SERVO CRUISE SERVO ELECTRONIC CRUISE GROUND BRAKE SW. CRUISE ENGAGER SW. CRUISE ENGAGER SW. CRUISE CONTROL ACTIVATOR 8 4 - — O O— 8 3 - — O ►...
• Page 70 RIGHT RIGHT REAR HAND DOOR DOOR JAMB JAMB SWITCH SWITCH 8911287 GROMMET 06 MODEL ONLY 6288872 FRONT DOME LAMP REAR DOME LAMP (06 MODEL ONLY) (43. 06 & 03 MODELS) 2973324 2973324 TERM vijQQQQQs TERM 40.1 ORN- 156-.8 WHT- -40-.8 ORN- SPLICE 40 -4 0 .8 ORN- 156 .8 WHT...
• Page 72 TO ROOF -9 .8 BRN 9 .8 BRN MARKER LPS (RPO 401) RADIO EQUIPMENT (RPO UM 6, UP8) SECTION A - PAGE 64...
• Page 73 2973384 FRONT SPEAKER 12004544 t r d 12004543 RADIO RECEIVER ® @ IS ® G O 1 5 H ® I E *"° a s ® ® ! ] •G* i.W % C=3B^ REAR FRONT FUSE BLOCK 150.8 BLK . b u s GROUND RADIO EQUIPMENT (RPO U63)
• Page 75 12010366 12010366 GROMMET GROMMET c ir c u it — | ^BR EAKER 668-2.0 DK BLU © I “ .1 12004140 669-2.0 BRN- RIGHT REAR WINDOW MOTOR RIGHT REAR WINDOW SWITCH c ir c u it *2JBREAKER 668-2.0 DK BLU- [Q[J •...
• Page 76 ^ 5 9 - ------- 1 50 3 .0 BLK } ---- — 150-3.0 BLK CUT OUT X F R A M E DE}------ 1 SWITCH " MOTOR 15300002 15300027 BRK GRN BLAZER ONLY □ 183 3.0 LT BLU- 60-3.0 ORN- 60 3.0 ORN/BLK- 183 3.0 LT BLU- 15300027 15300032...
• Page 78 DOOR LOCK RELAY 12034343 /TH1 2984378 ■295-1.0 GRA- c ir c u it RIGHT HAND BREAKER ■295-1.0 GRA- o n i i ■295 1.0 GRA- DOOR LOCK •294-1.0 TAN- ■294-1.0 TAN- 12 9 4 } 1 MOTOR -------294-1.0 TAN ----ll 12004140 60-2.0 ORN/BLK —...
• Page 79 £3 £5] 12015344 12015345 in II o 8911670 12010366 GROMMET GROMMET ru N CIRCUIT X M 1 c ir c u it RIGHT REAR RIGHT FRONT BREAKER 2 I BREAKER 295 1.0 GRA- ■295-1.0 GRA * = 7 - « 2 9 5 L DOOR LOCK DOOR LOCK 294-1.0 TAN-...
• Page 80 (S I IS ffl H IB O H (B j*** B D IS IS B Q D O S E > s 150-.8 BLK- (S (S s i s i i i i i •ATT io n a c c WINDSHIELD C i u N ? SHUN?
• Page 81 © © ® GD E © © S B ® ® ® 150 .8 BLK* a s © ® ® © © •ATT SHUNT SHUNT b u s Q 3 t M J J M L E M ] r 2 o P AOX MTU A«C STOP HA2 GROUND 25A |...
• Page 82 SHEET 2973407 METAL GROUND TRANSMISSION BACKUP 150.8 BLK- -eCgHi' LAMP SWITCH (AUTO TRANS) ONLY SPLICE 150 FROM RIGHT HAND TAIL. STOP. DIRECTIONAL ft SIDE MARKER LAMPS 2973431 MANUAL ONLY RIGHT HAND BACKUP .8 LT GRN LAMP - 75 .8 DK BLU 24 .8 LT GRN- -24 .8 LT GRN- ’•ibi...
• Page 83 BACKUP LAMP (PART OF RH TAIL. STOP AND DIR LAMP ASM) -24 .8 LT GRN PART OF LAMP ASM LAMP ASM GROUND 6288585 24 .8 LT GRN- 24 .8 LT GRN ■ FRAME GROUND TO BULKHEAD CONNECTOR FOR REMAINDER OF CIRCUIT 12015798 SEE BACK-UP LAMPS- UTILITY, SUBURBAN...
• Page 84 FROM R.H. SIDE FROM R.H. SIDE MARKER LAMP MARKER LAMP FROM R.H. TAIL, STOP & FROM R.H. TAIL. STOP & DIRECTIONAL SIGNAL LAMP DIRECTIONAL SIGNAL LAMP FROM RH FRONT & ► 150-.8 BLK REAR 150 .8 BLK CLEARANCE ► LAMPS 24 .8 LT GRN 24 .8 LT GRN RIGHT HAND...
• Page 85 R.H. SIDE MARKE LAMP R.H. TAIL, STOP & DIRECTIONAL HEADLAMP LAMP SWITCH TO COURT LAMP 9 .8 BRN- SPLICE 9 12015798 150 .8 BLK - BACKUP SHEET LAMP METAL GRN SPLICE 150 --------- 12015024 9 .8 BRN 9 8 BRN- 12020099 SPLICE 150 12020184...
• Page 87 RIGHT HAND SIDE MARKER LAMP HEADLAMP SWITCH BACK UP LAMP 9 .8 BRN- TAIL. STOP & DIR LAMP 'yC JD I 15 I 14 I 11 2 T | 12015798 — ■ 9 .8 BRN 9 .8 BRN 1 ________| [ 4 3 9 |4 2 0 || 12015024 ”...
• Page 88 R.H. TAIL, STOP & DIRECTIONAL HEADLAMP LAMP 6288424 SWITCH TO COURT. LAMP 6288424 L.H. TAIL, STOP & DIRECTIONAL LAMP TAIL LAMPS EXTENDED CAB PICKUP FUSE BLOCK SECTION A - PAGE 80...
• Page 89 R.H. TAIL, STOP & DIRECTIONAL LAMP LICENSE LAMP 12020099 n r Q i f t . < T ) 12015024 SPLICE 1 50 BACKUP LAMP 150 .8 BLK SHEET METAL GRN SPLICE 9 & 9 .8 BRN ® m 8911029 g) is} HOT AT L.H.
• Page 90 R.H. SIDE MARKER LAMP R.H. TAIL STOP & DIRECTIONAL LAMP L.H. TAIL, STOP & DIRECTIONAL LAMP L.H. SIDE MARKER LAMP LICENSE LAMP FLEETSIDE (E63) REAR WIDESIDE (R05) FUSE BLOCK SECTION A-PAGE 82...
• Page 91 RIGHT HAND HEADLAMP SWITCH 1 15 1 14 i . ? . u £ i r ^ 9 8 BRN L _ ^ _ J | 4 3 9 | 4 2 0 1 12015024 8917234 35 | 2 5 | 31 | 1 8 0 «...
• Page 92 R.H. TAIL, STOP & DIRECTIONAL HEADLAMP LAMP 6288424 SWITCH TO COURT. LAMP •9 .8 BRN- 9 .8 BRN' 2977645 BACKUP LAMP 9 .8 BRN DUAL 2977107 9 .8 BRN LICENSE SPLICE 9 .8 BRN- LAMPS < r SPLICE 12015024 2977107 2977159 12020099 2977107 9 .8 BRN...

Page 94: Fuse Block Detail

• Page 95 CAVITY "W "-C IR C U IT 50 IGN "O N " 2 5 A FUSED FEED — HTR & A/C CAVITY " I" CIRCUIT 3 9 CAVITY " A " —CIRCUIT 141 IGN "O N & CRANK" 2 0 A FUSED FEED IG N - "O N &...
• Page 96 CAVITY " W " - CIRCUIT 50 IGN “ O N " 2 5 A FUSED FEED — HTR & A/C CAVITY " I" CIRCUIT 39 CAVITY " A " -C IR C U IT 141 IGN "O N & CRANK" 20 A FUSED FEED IGN —"ON &...
• Page 97 START/IGNITION LT9-V8 BODY S T Y L E -4 2 SECTION B - PAGE 4 REAR FRONT...
• Page 98 □ □ □ □ C 3 C 3 TIMES GROUND C 3 o o [ “ ^ ---- + ■ — REAR FUSE BLOCK RIGHT HAND LEFT HAND BATTERY BATTERY POWER DISTRIBUTION-LL4 DIESEL SECTION B - PAGE 5...
• Page 99 POWER DISTRIBUTION L25 BODY STYLE- 4 2 FUSE BLOCK FRONT SECTION B - PAGE 6 REAR...
• Page 100 POWER DISTRIBUTION LE8 V -8 BODY S T Y L E -3 2 FUSE BLOCK SECTION B - PAGE 7 REAR...
• Page 101 POWER DISTRIBUTION LT9, V -8 BODY STYLE- 4 2 FUSE BLOCK SECTION B - PAGE 8 REAR...
• Page 102 ■32 BLK (BATT CABLE) POWER DISTRIBUTION L 0 5 - V 8 FRONT REAR FUSE BLOCK SECTION B - PAGE 9...
• Page 103 CLUTCH SWITCH (MAN TRANS) NEUTRAL START & BACK-UP SWITCH (AUTO TRANS) TO AIR SWITCH & M 4 0 KICKDOWN RELAY SHEET ENG INE M E T A L G R O U N D G R O U N D POWER DISTRIBUTION P42 &...

Page 104: Marker Lamps

• Page 105 R.H. R.H. SIDE MARKER SIDE MARKER SHEET LAMP LAMP METAL GROUND 6 2 9 4 0 1 5 1151-.8 BLK 12004628 R.H. PARK & R.H. TAIL. DIRECTIONAL HEADLAMP STOP, & LAMP DIRECTIONAL SWITCH LAMP •15-.5 DK BLU SPLICE 9 9 .8 BRN- R.H.

Page 106: Hazard Lamps

• Page 107 SIDE MARKER DIRECTIONAL LAMP SIGNAL SW LAMP—P32 (E32/E33 ONLY —P42) 19-1.0 DK GRN- ■18-1.0 YEL- 16-.8 PPL- PROVISIONS FOR -15 .5 DK BLU RH TAIL. STOP & DIRECTIONAL LAMP (P32) 6294015 R.H. TAIL, STOP & DIRECTIONAL LAMP (P42) R.H. PARK & DIRECTIONAL LAMP .8 PPL...

Page 108: Horn

• Page 109 8 .5 GRA WIPER, WASHER SWITCH ■150 8 BLK SHEET LAMP METAL GROUND 8 9 0 5 3 8 1 WINDSHIELD OFF LO WIPER 150 .8 B L K ----------------------- — I jb o ] E > WASHER - 9 4 .8 PNK SWITCH 1 91 I I 92 I ■...
• Page 110 ru ___ n f-i—r < 2 - START (IGNITION L 2 5 - 6 CYL. BATTERY BODY STYLE- 4 2 SECTION B - PAGE 17 REAR FRONT...
• Page 111 —> w N — i* I T ' - * ----- ----------►!----------- - — « ----------- f c - V — - • 'J J B ■32 BLK (BATT CABLE) - j-i--------n — P iil □ □ □ □ W o T Ih s —...
• Page 112 RED (P32) THERMO HW — - ° \ v v ' — RED-THERMO HW TIMES 32 BLK C 3 D 3 — n --------n — _ - n ____ □ __ GROUND C D O D J FUSE BLOCK RIGHT HAND LEFT HAND BATTERY BATTERY...
• Page 113 START/IGNITION - L05-V8 SECTION B - PAGE 20...
• Page 114 TO PARK/ CLUTCH NEUTRAL SWITCH RELAY (MAN TRANS) (AUTO ONLY) 2 -5 .0 RED- 8 9 1 1 9 2 1 NEUTRAL START & BACK-UP TO CLUTCH START SWITCH (MAN TRANS) NEUTRAL SAFETY SWITCH (AUTO TRANS) START/IGNITION L 05 -V 8 FRONT P42 &...

Page 115: Throttle Body Injection

• Page 116 GROMMET TO ECM 1 2 0 2 0 1 0 7 FUEL PUMP RELAY STEPPER MOTOR § 4 44 IDLE AIR CONTROL 1 2 0 1 5 7 9 GROUND ALTERNATOR BRACKET SYSTEM GROUND NO. 2 (LH REAR CYLINDER HEAD) FUEL PUMP OIL PRESSURE SENSOR &...

Page 117: Emission Controls

• Page 118 ENGINE 150 .8 BLK © GROUND RIGHT HAND 9 3 6 .8 YEL DIVERT 3 9 .8 PNK/BLK SOLENOID 12015792 (NA5) 39 .8 PNK/BLK- ENGINE n— r n - SPLICE 93 6 l f . > 9 3 6 .8 YEL .
• Page 119 BODY GROUND RIGHT HAND DIVERT SOLENOID (NA5) DIVERTER SYSTEM RELAY (NA5) DIVERTER MODULE (NA5) LEFT HAND DIVERT SOLENOID EMISSION CONTROLS-LE8 SECTION B - PAGE 26...
• Page 120 FAST IDLE SOLENOID 1 2 0 0 4 2 6 7 I n FUEL PRESSURE WATER IN FUEL SENSOR FUEL HEATER FUEL SHUT OFF VALVE EMISSION CONTROLS!DIESEL 1 -L L 4 SECTION B - PAGE 27 TO SPLICE 39...
• Page 121 1 2 0 2 0 2 7 4 FUEL SHUT OFF VALVE GLOW PLUGS —LL4 DIESEL SECTION B - PAGE 28...
• Page 122 TRANSMISSION SPLICE 4 2 2 4 2 2 .8 TAN/BLK- 4 2 2 .8 TAN/BLK KICKDOWN TO ALDL SOLENOID TO AIR SWITCH 55 .8 ORN 2 9 8 4 0 9 2 KICKDOWN RELAY 1 2 0 2 0 7 5 3 39 .8 PNK/BLK —...
• Page 123 THROTTLE POSITION SENSOR COOLANT TEMP SENSOR E.S.C. SENSOR E.S.C. HYBRID FUNCTION O X Y G E N SENSOR 1 2 0 1 5 7 9 1 ELECTRONIC CONTROL M O DULE-INPUTS L05-V 8 SECTION B - PAGE 30...
• Page 124 ■450-1.0 BLK/WHT - ■ 439-1.0 PNK/BLK -4 3 9 -1 .0 PNK/BLK - SPLICE 4 4 0 -4 4 0 -1 .0 ORN 4 4 0 -1 .0 ORN -4 4 0 -1 .0 ORN- ■440 1.0 ORN -4 4 0 -1 .0 ORN- GROMMET ■485- 8 BLK 1 2 0 2 0 1 0 7...
• Page 125 ELECTRONIC SPARK TIMING E.V.R.V. SWITCH FUEL PUMP RELAY FUEL PUMP OIL PRESSURE SENSOR & SWITCH 1 2 0 4 8 3 9 0 ELECTRONIC CONTROL M ODULE-O UTPUTS L05-V 8 TO OIL SECTION B - PAGE 32 PRESS GAUGE...
• Page 126 TO ECM ELECTRONIC CONTROL MODULE L05-V8 SECTION B - PAGE 33 4 3 9 - 8 PNK/BLK...
• Page 127 CIRCUIT WIRE CIRCUIT WIRE CAVITY COLOR DESCRIPTION COLOR CAVITY DESCRIPTION SIZE SIZE 4 6 5 DK GRN/WHT FUEL PUMP RELAY DRIVE NOT USED NOT USED 4 3 6 AIR SW SOLENOID NOT USED 4 4 4 LT GRN/BLK STEPPER COIL B LOW 4 3 5 EVRV 4 4 3...
• Page 128 INSTRUMENT PANEL CLUSTER CONNECTOR SEE PAGE BRAKE PRESSURE WARNING 33 .5 TAN/W HT- LE8, L25 LE8, L25 (BODY STYLE (BODY STYLE 42 ONLY) 42 ONLY) LL4 (ALL BODY LL4 (ALL BODY STYLES) STYLES) BRAKE WARNING SYSTEM SECTION B - PAGE 35...
• Page 129 —, FOR CONTINUATION OF WIRING | j— SEE BRAKE WARNING SYSTEM 8 9 1 1 1 4 9 is o 6 2 9 4 4 6 8 7=v_ 15 0 .8 BLK VACUUM SWITCH 3 3 .8 TAN/WHT PARK 150 .8 BLK BRAKE <LL 4 1 2 0 1 5 7 9 2...
• Page 130 ILLUM ILLUM ILLUM TRANSMISSION WIPER/WASHER HIGH BEAM DIAL LAMP SWITCH LAMP SOCKET (LE8, LL4 ONLY) 89 0 5 3 8 1 BRAKE WINDSHIELD WIPER 150 .8 BLK- 1 5 0 11 5 0 1 L T J J WASHER l 9 4 l --------- 1<...
• Page 131 ■419-.8 BRN/WHT------------------------------------------------------ ^ TO ECM BRAKE PRESSURE WARNING SWITCH DIMMER 33 .8 TAN/WHT SWITCH 8 9 0 0 8 5 5 PRESSURE SWITCH 9 3 1 . 8 DK BLU 139 .8 PNK/BLK 9 3 1 -1 .0 DK BLU' 8 9 0 0 4 2 0 2 9 7 7 2 5 3 4 1 9 -1 .0 BRN/W HT'...
• Page 132 (ST I I RING COL S WI TCHES I ILLUM ILLUM ILLUM DIRECTIONAL HIGH BEAM SIGNAL SW •16 .8 PPL- © ■27-1.0 BRN- TO l/P BRAKE CONN H O T )*' CHOKE CHECK CHECK WARNING ENGINE ENGINE LAMP LAMP LAMP 12004147 (LE8) (LE8,...
• Page 133 ILLU M ILLUM ILLUM COOLANT COOLANT METAL FUEL PUMP H IG H B E A M FUEL PUMP TEMP TEMP TEMP PRESS OIL PRESS SWITCH SENDER SWITCH SENDER SENSOR & SW. ( f ) (D Ct) 6 2 8 8 7 0 4 1 2 0 4 5 8 9 6 INSTRUMENT PANEL GAGES FRONT...
• Page 134 TRANSMISSION BACK-UP LAMP SWITCH IS IS C D B E (D 0 " * * (AUTO TRANS ONLY) (D ID □ B E Q E < M T * MANUAL ID (5 ID f t E ID E TRANSMISSION •ATT ONLY SHUNT [ b A...
• Page 135 R.H. PROVISIONS FOR SIDE MARKER R.H. TAIL. STOP LAMP & DIRECTIONAL LAMP (P32) R.H. TAIL, STOP & DIRECTIONAL LAMP (P42) HEADLAMP SWITCH 2 9 8 4 8 5 5 SPLICE 9 R.H. 9 .8 BRN- LICENSE LAMP ■9 .8 BRN- 9- 8 BRN 9 -1 .0 BRN- L.H.
• Page 136 R.H. SIDE MARKER LAMP PARK H E A D f PARK O 1 2 0 0 4 6 2 8 R.H. TAIL. STOP & DIRECTIONAL HEADLAMP LAMP (P42) SWITCH PROVISIONS FOR LICENSE LAMP (P32) R.H. LICENSE LAMP (P42) SPLICE 9 ■9 .8 BRN- ------- 9- 8 BRN .8 BLK...

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LS Engine DIY

Do It Yourself LS Engines

Upgrading to Gen III LS-Series PCM: Cruise Control Guide

February 15, 2015 by LS Engine DiY

All Gen III vehicles were available with cruise control. Engines with a cable-actuated throttle body require an electronic cruise control module with an internal stepper motor to pull and release a throttle cable to maintain vehicle speed. Engines with an electronic throttle body rely on the TAC module to increase and decrease throttle blade angle to maintain vehicle speed.

Cable Throttle Systems

Early cruise control systems took control of the throttle blade angle through a vacuum-operated actuator that pulled and released a throttle cable. The actuator relied on engine vacuum for operation. Early cruise control systems have a lag response to driver commands. Making cruise control performance worse is an aged diaphragm that has developed a leak and no longer operates properly.

Electronic throttle systems use a TAC module (right), while cable throttle systems use a cable-driven cruise control module (left). The TAC module is wired to a motor mounted within the throttle body assembly and uses PCM data to change throttle angle to maintain cruise control vehicle speed. The cable throttle cruise control module shown here also uses PCM data to maintain cruise control vehicle speed, but must manually pull the throttle linkage to change the throttle angle.

This tech tip is from the full book, HOW TO USE AND UPGRADE TO GM GEN III LS-SERIES POWERTRAIN CONTROL SYSTEMS .

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Newer cruise control systems abandoned the vacuum actuator for an electronic module with an internal stepper motor to pull and release a throttle cable to maintain vehicle speed. These systems have a better performance feel than the old vacuum-type systems. The required components of the cruise control system, however, have not changed much.

Required Components

To install a GM cruise control module for your cable throttle system, several components are required. Most of them, such as cruise control switches, clutch switch, and brake switches, may already be in your car. Any missing components can either be sourced from a salvaged GM vehicle or through the aftermarket.

Cruise Control Module: The cruise control module for cable throttle vehicles is a relevant discussion for Gen III PCMs because of the PCM’s availability of primary and secondary VSS outputs that may be used to satisfy the cruise control module’s 4,000 pulse-per-mile input requirement. Also, the 1999–2002 Camaro/ Firebird cruise control modules require cruise inhibit and cruise-enabled status communication signals with the PCM .

Early GM systems used a vacuum-controlled actuator to pull a throttle cable. These systems require a VSS (most commonly a 2,000 pulse-per-mile signal) to maintain cruise control vehicle speed. Rather than using an internal motor like the newer cable-driven cruise control modules, these early units use engine vacuum to control a diaphragm that pulls a throttle cable. The result is a lazy response to the driver’s cruise control commands.

This 1996-newer GM cruise module assembly contains a circuit board for processing cruise control logic, an internal motor to operate a worm-driven gear, and a short braided strap to pull the throttle cable. This cruise control module uses PCM data to control the movement of the throttle cable when cruise control is active.

This Rostra cruise control switch (# 250-3020) may be used in a GM application for on/off and set/coast signals. The aftermarket offers several types of cruise control switches for different steering column configurations. If you cannot identify one to suit your application, you could make your own set of dash or center console-mounted switches. With an on/off switch, two momentary switches, and little creativity, you can create an inexpensive cruise control switch solution.

Cruise control modules compatible with Gen III conversions are plentiful.  You may choose from cruise control modules found in 1996- newer Vortec trucks and LS series vehicles. The cruise control module receives signals from several switches and, when necessary, takes control of throttle blade angle through a cable attached to the engine’s throttle body. Installation is rather simple. The most difficult part may be adapting the cruise control throttle cable to your throttle body’s linkage if the cable end does not match.

PCM: In production vehicles, the PCM is used to output a 4,000 pulse-per-mile VSS signal to the cruise control module. This is a common pulse count used with many early GM ECMs and VSS buffer boxes. An optional cruise-engaged status signal is available for communication between the PCM and cruise control module. For retrofits using a 1999–2002 Camaro/Firebird cruise control module, the cruise engaged status and cruise inhibit signal wires must be used.

VSS Signal: The 4,000 pulse-per-mile VSS input to the cruise control module is required, but the PCM is not required to provide it. Retrofit projects sometimes introduce VSS buffer modules to receive a VSS signal that is not compatible with the Gen III PCM and to provide several VSS outputs for devices such as the speedometer or PCM.

Not all aftermarket cruise control switches provide the signals required by the GM systems. This Rostra switch does not provide an independently pulsed 12V signal fo the resume/accel function. In such cases, only the on/off and set/coast switches may be used.

1996-newer GM cruise control module schematic looks like this. Notice the PCM cruise status and cruise inhibit signals are only required for 1999–2002 Camaro and Firebird cruise control modules. In general, the cruise control module requires 12V switched ignition, ground, VSS, cruise control switches, normally open brake switch (stop lamp switch), normally closed brake switch (commonly a torque converter clutch switch), and a manual transmission clutch switch (if so equipped).

This schematic represents a typical GM cruise control switch wired to a TAC module. The TAC module generally requires 12V switched ignition, ground, PCM serial data circuits, cruise control switches, normally open brake switch (stop lamp switch), normally closed brake switch (commonly a torque converter clutch switch), and a manual transmission clutch switch (if so equipped).

A VSS buffer module may also be used to provide a 4,000 pulse-per-mile VSS signal to the cruise control module. Remember, however, the Gen III PCM has two configurable VSS outputs to choose from that provide a 4,000-pulse-per-mile signal dedicated to the cruise control module. (See Chapter 15, Project 1, on page 112 for setting the 4,000 pulse-per-mile VSS signal with EFILive.)

Cruise Control Switches: The required cruise control switch signals the multifunction lever of GM steering columns. The on/off signal is normally open switched 12V, the set/ coast signal is momentary 12V, and the resume/accel signal is momentary 12V.

Rostra Precision Controls offers a variety of cruise control switches that may be used if your steering column’s multifunction lever does not have the necessary cruise control switches. (See Chapter 15, Project 1, on page 112 to see an early GM steering column with only a set/coast cruise control switch.)

Brake Switch: The cruise control module requires two brake switch signals. A normally closed 12V switch applies power to the clutch/brake switch input (pin D) and a normally open 12V switch applies stop lamp voltage to the brake input (pin G). These signals are used to disengage cruise control when the brake pedal is depressed.

Clutch Switch: If using a manual transmission, a normally closed clutch switch should be wired on the same circuit as the normally closed brake switch. Depressing the clutch switch removes 12V from the cruise control module (pin D) to disengage cruise control.

Operation Overview

With the exception of the 1999– 2002 Camaro/Firebird cruise control modules, the 1996-newer truck and 1998 Camaro/Firebird cruise control modules can be used as standalone units. These modules require 12V ignition, ground, cruise control switch signals, brake switch signal, clutch switch signal, stop lamp switch signal, and a 4,000pulse-per-mile vehicle speed signal. Once installed in a retrofit vehicle, the performance is improved compared to early cruise control systems operated by engine vacuum.

Set/Coast: To set cruise control, the cruise control module requires a 12V switched-on signal and a 12V momentary set signal from the multifunction lever. With the 12V on signal present at the cruise control module and the vehicle at a desired speed, pushing the set button adds the vehicle’s current speed to the cruise control module’s memory.

The driver may remove his or her foot from the accelerator pedal and the cruise control module overrides the throttle blade angle to increase or decrease vehicle speed. Pressing and holding the set/coast button causes the vehicle to coast to a reduced speed. Releasing the set/coast button stores the new reduced vehicle speed in the cruise control module’s memory. Quickly pressing and releasing the set/coast button subtracts 1 mph from the cruise control module’s memory.

Resume/Accelerate:  Once cruise control is active and the driver depresses the clutch or brake pedal, the cruise control module no longer controls throttle blade angle. The previously set vehicle speed remains stored in the cruise control module’s memory. Sliding the resume/accel switch requests the cruise control module to take over throttle blade angle and accelerate the vehicle to the previously set vehicle speed.

Sliding and holding the resume/ accel switch increases vehicle speed until the switch is released. The new vehicle speed is stored in the cruise control module’s memory. Quickly sliding and releasing the resume/ accel switch adds 1 mph to the cruise control module’s memory.

If the cruise control on/off switch is set to off or the vehicle is shut off, the cruise control module’s memory is erased and sliding the resume/accel switch does not return the vehicle to a previously set speed.

Erasing Cruise Speed Memory: When the driver disengages cruise control by depressing the clutch or brake pedal, the cruise control module retains its memory and allows the driver to use the resume/accel switch to resume the vehicle speed stored in memory. To clear the cruise control module’s memory of vehicle speed, turn off the on/off switch or shut off the vehicle’s ignition switch. This removes 12V power from the cruise control module and clear its memory.

Disengaging Cruise Control: The cruise control module retains the set vehicle speed in its memory until it loses 12V power through the cruise control on/off switch or the vehicle’s ignition switch. To disengage (but not disable) the cruise control module’s control of throttle blade angle, gently apply the clutch or brake pedal to momentarily remove 12V power from the cruise control module’s brake/clutch signal input.

To disable cruise control, slide the cruise control on/off switch to the off position.

Inhibit Signal

Be cautious of cruise control modules from 1999–2002 Camaros/ Firebirds. These cruise control

modules are “more intelligent” than truck modules. In the 1999–2002 Camaro/Firebird, the PCM may inhibit (prevent) cruise control operation based on vehicle speed, park/neutral switch signal, engine RPM, or battery voltage. If the PCM commands the cruise inhibit signal to the cruise control module and the cruise control module returns an active cruise-engaged status signal, the PCM sets a DTC related to the cruise control system.

Most people find this extra layer of protection unnecessary and prefer a cruise control module from a 1996-newer truck or 1998 Camaro/ Firebird. The 1998 Camaro/Firebird PCM cannot output a cruise inhibit signal, so the 1998 Camaro/Firebird cruise module functions the same as the 1996-newer truck modules.

Identifying a 1999–2002 Camaro/ Firebird cruise control module is rather easy. All ten harness connector cavities are used. Vehicles with the cruise inhibit signal require its use when installing the cruise control module in a retrofit vehicle. While you likely do not see a wire in connector

cavity H for any other vehicle, a quick visual inspection of the wire harness shows whether the cruise inhibit signal is required.

Electronic Throttle Systems

All Gen III vehicles with an electronic throttle body rely on the TAC module for cruise control operation. During normal engine operation, the TAC module is used to increase and decrease the throttle blade angle. By using the available cruise control switch inputs, the TAC module can respond to the driver’s cruise control commands to maintain vehicle speed.

Being fully integrated into the electronic throttle system, the driver’s cruise control commands are instantaneously applied to the throttle and the feel of acceleration and deceleration is smooth and seamless.

The switches and inputs are very similar to those of cable-operated cruise control modules.

It’s likely that after an electronic throttle installation your vehicle will have all of the components necessary for integrated cruise control. By using the TAC module’s cruise control switch inputs and brake/clutch switches, any retrofit vehicle can be ready for cruise control. The following switch signals are required by the electronic throttle system for cruise control operation.

Cruise Control Switch: The required cruise control switch signals are no different than those for Gen III vehicles with cable throttle body and cruise control module. The on/ off signal is normally open-switched 12V, the set/coast signal is momentary 12V, and the resume/accel signal is momentary 12V. If your retrofit vehicle does not have a multifunction lever on the steering column with cruise control switches, you can find them in the aftermarket.

Brake Switch: The cruise control system requires two brake switch signals. A normally closed 12V switch applies power to the TCC brake switch input of the PCM and a normally open 12V switch applies stop lamp voltage to the stop lamp input of the TAC module. These signals are used to disengage cruise control when the brake pedal is depressed.

Clutch Switch: If using a manual transmission, a normally closed 12V clutch switch must be wired to the PCM (blue connector, pin 35). Depressing the clutch switch removes 12V from the PCM’s clutch switch input to disengage cruise control.

Written by Mike Noonan and Posted with Permission of CarTechBooks

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