Cruise Control System Chevrolet Camaro II

DESCRIPTION

The cruise control system uses engine manifold vacuum to control the throttle servo unit. The servo moves the throttle by receiving controlled vacuum from a transducer. The system is operated by a switch on the end of the turn signal lever. Some diesel and A/C equipped models use a vacuum pump or aspirator system to assist vacuum production.

ENGAGEMENT SWITCH

The switch has 3 positions. To operate the system, driver accelerates vehicle to desired speed and presses switch to first detent position. When switch is released, system will maintain vehicle speed. To reduce speed or disengage system, switch is depressed to second detent position.

When speed has dropped to desired rate, button is released and cruise control takes over. Moving switch to "RESUME" position allows normal operation. If system has been disengaged by brake pedal, moving the slider to "RESUME" will bring vehicle speed back to pre-set level. When slider is moved to "OFF" position, system is disengaged and speed memory is erased.

BRAKE RELEASE SWITCH & VALVE

The cruise control can be disengaged by depressing brake pedal lightly. A set of contacts in brake light switch open and cut power to system. A vacuum valve at pedal also opens to ensure system disengagement if brake switch fails.

SERVO UNIT

Unit is a vacuum actuated variable position diaphragm assembly which operates carburetor throttle when system is in operation. It is powered by controlled vacuum from transducer and operates throttle linkage by means of a chain or rod.

TRANSDUCER

The transducer provides the servo unit with controlled vacuum which will maintain driver selected speed. If vehicle speed drops, the transducer supplies less air bleed and vacuum in servo increases to open the carburetor throttle valve.

When vehicle speed increases, air bleed increases and vacuum in servo drops to close carburetor throttle valve. The transducer also drives the speedometer. The speedometer cable from the transmission drives the transducer, which drives a second cable within the unit at a one-to-one ratio.

ADJUSTMENTS

Note. The components of this system are designed to be replaced should they become inoperative. However, the following adjustments may be made to correct speed drop or increase, or misalignment of brake switch.

BRAKE AND VACUUM SWITCHES

With pedal fully depressed, push switches into holder until fully seated. Pull pedal back to move switches to proper position. Depress and pull pedal to stop once more to ensure switches are seated in properly adjusted position.

Cruise Master Transducer. Scheme 1

Servo-throttle linkage adjustment is made by bead chain, turnbuckle type link, cable-jam nut or holes in the servo rod-power unit link. Engine must be hot, idle speed properly adjusted, throttle closed and ignition off prior to adjustment.

Servo-Link Rod (E & G Models W/ 4.1L V6 & A Models W/ 4.3L V6)

Ignition should be off, fast idle cam off and throttle completely closed. Hook rod through tab on servo. Adjust length so that rod fits over the end of stud. Install the retainer.

Servo Link Rod ("B", "C" & "E" Models With 5.0L V8)

Adjust rod length to minimum slack with carburetor lever on slow idle screw and engine not running. Idle load control must be fully retracted when retainer is installed.

Servo Link Rod ("G" Models With 4.3L V6)

Adjust rod length to minimum slack with injection pump on slow idle screw.

Servo Link Rod ("A" Models With 3.0L V6)

Adjust rod with ignition off, fast idle cam off and throttle completely closed. Hook rod through tab on servo assembly. Adjust length so that rod fits over end of stud. Install retainer.

Bead Chain

1. Assemble chain to be taut with carburetor in hot idle position and idle control solenoid de-energized. Place the chain into the swivel cavities which permit chain to have a slight amount of slack. Place retainer over the swivel and chain assembly.
2. Retainer should be positioned to rest between balls. Cut off chain flush with swivel to remove excess length. Chain slack should not to exceed 1/2 diameter of ball stud when measured at hot idle position, with idle control solenoid de-energized and swivel disconnected from ball stud.

Cable Jam Nut ("J" Models With 2.0L 4-Cyl.)

1. With cable installed on bracket and stud, install cable to servo bracket. Using third ball on servo chain, install chain on cable. With throttle completely closed, (ignition and fast idle cam off), adjust cable jam nuts until chain is almost tight (some slack).
2. Tighten jam nut. Remove plastic retainer used to retain boot in depressed position and pull servo boot over cable washer.

Cable Adjustment ("A" Models With 4.3L V6)

Select hole in servo which leaves the minimum amount of cable slack. The injection pump should be on hot idle stop.

Cable Adjustment ("J" Models 1.8L 4-Cyl.)

1. With cable installed in bracket on adapter, install cable end key hole slot over stud on TBI lever by rotating TBI lever up so stud engages slot on cable end. Release TBI lever.
2. Pull servo assembly end of cable toward servo without moving TBI lever. If one of the 4 holes in the servo assembly tab lines up with cable pin, connect pin to tab with retainer.
3. If a tab hole does not line up with pin, move the cable away from servo assembly until next closest tab hole lines up. Connect pin to tab with retainer. Do not stretch cable to make a particular tab hole connect to pin. This would prevent engine from returning to idle.

1. Before any adjustment is made to transducer, inspect all vacuum hoses for damage. All hoses should be properly connected, with no kinks or pinches, and no leaks should be detected. Check and adjust (if necessary) electric and vacuum brake release switches (as previously outlined). Check, and if necessary, adjust servo bead chain (as previously outlined).
2. If cruising speed is lower than the engagement speed, loosen the orifice tube lock nut and turn outward slightly. If cruising speed is higher than engagement speed, turn tube inward. Each 1/3 turn will alter engagement speed 1 mph. Tighten lock nut and test at 55 mph.

Note. Do not attempt to remove orifice tube. Once removed, it cannot be installed.

WILL NOT ENGAGE - SYSTEM INOPERATIVE

Throttle linkage disconnected. Vacuum leak in servo unit. Restricted or plugged vacuum line. Brake pedal vacuum valve out of adjustment. Resume solenoid valve inoperative. Blown fuse. Loose electrical connections. Open in wiring. Engagement switch malfunction.

DOES NOT CRUISE AT ENGAGEMENT SPEED

Orifice tube misadjusted. Speedometer cable kinked. Transducer malfunction. Throttle linkage too loose. Vacuum leak.

SYSTEM HUNTS, PULSES OR SURGES

Bead chain loose. Air leak in hoses. Defective or improperly positioned drive cables and/or casing assembly. Defective transducer.

BRAKE PEDAL DOES NOT DISENGAGE SYSTEM

Brake switches misadjusted or defective.

SYSTEM ACCELERATES OR APPLIES FULL THROTTLE WHEN ENGAGED

Defective transducer. Improperly connected manifold vacuum.

CANNOT ADJUST SPEED DOWNWARD

Defective engagement switch or wiring.

VACUUM BLEED OFF WHEN SYSTEM DISENGAGED

Crossed vacuum hoses at transducer.

DOES NOT ENGAGE OR ENGAGES AT SPEEDS LOWER THAN 30 MPH

Defective transducer.

SPEED DROPS OFF EXCESSIVELY ON INCLINES

Throttle linkage too loose. Vacuum source hose restricted. Cruise system not connected to auxiliary vacuum pump or aspirator. Check valve reversed or stuck open. AIR management valve diverting (aspirator equipped vehicles only) causing line pressure to aspirator to be reduced.

CONTROL LEVER SWITCH

1. Disconnect connector from the engagement switch. The connector is located below and to the left of steering column. Connect ohmmeter to the Brown and Blue wires. Slide resume switch to "ON". Ohmmeter should indicate continuity.
2. Push engage button all the way in. An open circuit should be indicated. Check continuity of Brown and Black wires. An open circuit should be indicated. Depress engagement button and release half way. There should be continuity.
3. Connect ohmmeter to Blue and Black wires with switch in "ON" position. With button released, there should be no continuity. With button fully depressed, continuity should be indicated.

HARNESS AND TRANSDUCER

1. With engagement switch disconnected, check resistance of Dark Green wire in wiring harness. If transducer is well grounded, resistance should be 29-36 ohms. If resistance is not to specifications, disconnect connector at transducer and at resume solenoid.
2. Measure resistance of Dark Green wire. It should be 21-24 ohms. If reading is above or below specification, wiring harness should be replaced. With connectors to transducer disconnected, measure the resistance of solenoid coil by connecting ohmmeter to "HOLD" terminal and ground.
3. Resistance should be 5 to 6 ohms. If measured value is 4 ohms or less, coil circuit is shorted. If value is 7 ohms or more, there is excessive resistance in the circuit. If any value other than 4 to 6 ohms is read, unit should be replaced.

SERVO & VACUUM

To determine the condition of the diaphragm, remove hose from the servo unit and apply 14 in. of vacuum to the tube opening and hold or one minute. The vacuum should not leak down more than 5 in. in one minute. If leakage is detected, replace servo.

RESUME VALVE

Disconnect electrical connector from transducer "HOLD" terminal. Apply 12 volts direct current to "HOLD" terminal connector cavity. Solenoid should engage. Remove the vacuum source and solenoid should disengage. A click should be heard each time solenoid engages or disengages.

Note. Do not reverse polarity when applying power or radio noise suppression diode will be damaged.

VACUUM PUMP ASSISTED SYSTEMS

Blow low pressure air into port "A" while port "B" is plugged and then plug port "A" and blow into port "B". (Scheme 2) In both cases, air should exit at port "C". If not, clean or replace check valve. To check air flow in opposite direction, blow air into port "C". No air should exit from ports "A" or "B".

Vacuum Assisted Cruise Control Test. Scheme 2

DIESEL VACUUM REGULATOR

Disconnect hose from transducer at regulator valve. Attach vacuum gauge to regulator valve. Start engine and observe vacuum. Vacuum should be between 6 and 7 in. Hg. If reading is above 8 in. Hg. or below 6 in. Hg., replace regulator valve.

ASPIRATOR ASSISTED SYSTEMS

1. Connect a vacuum gauge to point "A", or point "B" on Buick and Oldsmobile with 5.0L V8 engine. (Scheme 3) Run engine in closed loop mode at 2500 RPM. Vacuum gauge should show a minimum reading of 5 in. Hg. If reading is low, remove and clean aspirator with mineral spirits.
2. Check AIR pump for output. Plug the 2-port check valve at port "B". Blow low pressure air into hose at point "C". Air should exit freely from point "A". Reverse the procedure so that point "A" is plugged and air will exit freely from point "B".
3. If air does not exit freely from both directions, clean or replace 3-port check valve. Plug air flow at point "B" and blow air into point "A". Then plug point "A" and blow into point "B". No air should exit from point "C".

Typical Aspirator Assisted Vacuum System Vacuum gauge should show a minimum of 5 in. Hg. Scheme 3

Removal & Installation

1. Disconnect battery ground cable. Remove lower instrument panel trim panel and disconnect switch harness connector. Place shift lever in "L" position and turn signal in right turn position. On tilt column models, place column in full up position. Connect a 24" piece of wire to connector and wrap it with tape.
2. Pull turn signal lever straight out of column. Pull engagement lever and harness out of column and disconnect follower wire. Leave follower wire in column to guide new harness back in. To install, reverse removal procedure, using follower wire to guide harness in column.

Disconnect battery ground cable. Disconnect speedometer cables at transducer. Disconnect vacuum and wiring harness from transducer. Remove screws mounting transducer to bracket, and remove transducer. To install, reverse removal procedure.

GM Cruise Master Vacuum and Wiring Diagram. Scheme 4

GM Cruise Master Wiring Diagram. Scheme 5