Cruise Control System Buick Century V

DESCRIPTION & OPERATION

Cruise control is designed to maintain a desired vehicle speed greater than 25 MPH. System capabilities include cruise, coast, resume speed, accelerate, "tap-up" and "tap-down".

Cruise control system operates a mechanical linkage to the throttle by means of cruise control module linkage.

MULTIFUNCTION LEVER

Main switch and set switch are located on multifunction lever, which also serves as turn signal lever and contains wiper/washer controls. Main switch turns the cruise control system on and off, returns cruise control operation to last speed setting and also increases set speed. Set switch, located on end of multifunction lever, is used to initially set the desired cruise speed and to allow cruise control system to temporarily coast to a lower speed. Refer to Fig. (Scheme 1).

CRUISE CONTROL MODULE

Cruise control module contains an electronic controller and electronic motor. Controller monitors vehicle speed and operates electric motor. In response to controller, motor moves a connecting strap that is attached to cruise control cable. Cruise control module is located in left side of engine compartment, on shock tower.

BRAKE & CLUTCH RELEASE SWITCHES

The brakelight/TCC switch disengages cruise control operation electrically when brake pedal is depressed. This is done by breaking electrical circuit to cruise control module. Vehicle speed at brake actuation will be stored in system memory.

VEHICLE SPEED SENSOR (VSS)

VSS is a Permanent Magnet (PM) generator mounted in transaxle or transmission. Sensor generates vehicle speed information in the form of a sine wave. VSS signal is sent to ECM, which converts sine wave into MPH signal. MPH signal is then sent to cruise control module to monitor vehicle speed.

BRAKE & CLUTCH RELEASE SWITCHES ADJUSTMENT

With brake or clutch pedal released, switch plunger should be fully depressed against pedal shank. To adjust, depress pedal and push switch until switch body is fully seated on clip. Pull pedal towards rear of vehicle, against pedal stop (clicking should be heard while pulling pedal). Switch will adjust to proper position in clip. Check brakelights for proper operation.

CRUISE CONTROL LINKAGE

Disconnect cable conduit at accelerator cable bracket. With throttle closed, lock cable conduit by pressing down on cable lock. When cable is in unlocked position, and throttle closed, cable adjustment spring removes appropriate amount of slack. Cable lock must be fully extended to allow proper adjustment spring operation prior to locking.

CRUISE CONTROL WILL NOT ENGAGE

Note. This procedure has been updated per TSB 43-81-29 dated November 4, 1994.

1. Turn ignition off. Disconnect cruise control module connector. Turn ignition on (engine off). Connect test light between connector terminal "F" (Pink wire) and ground. If test light does not light, repair open circuit in Pink wire.
2. If test light lights, connect test light between connector terminals "F" (Pink wire) and "E" (Black wire). If test light does not light, repair open circuit in Black wire.
3. If test light lights, leave ignition on and turn cruise control switch to RUN position. Connect test light between connector terminals "B" (Dark Blue wire), "C" (Gray/Black wire), and ground. If test light lights, check Dark Blue or Gray/Black wires for a short to voltage. If wires are okay, replace multi-function lever.
4. If test light does not light, connect test light between connector terminal "D" (Purple wire) and ground. If test light lights, go to step 6). If test light does not light, go to next step.
5. Backprobe brake switch connector C2, between terminal "B" (Purple wire) and ground. If test light lights, repair open circuit in Purple wire. If test light does not light, backprobe test light at brake switch connector C2, between terminal "A" (Brown wire) and ground. If test light does not light, repair open circuit in Brown wire. If test light lights, check for poor connection at brake switch connector. If connector is okay, replace brake switch.
6. Connect test light between connector terminal "G" (Yellow wire) and ground. If test light lights, check Yellow wire and brake switch for a short to voltage. If test light does not light, go to next step.
7. Connect test light between connector terminal "A" (Gray wire) and ground. If test light does not light, repair open circuit in Gray wire. If test light lights, turn ignition off. Reconnect cruise control module. Go to next step.
8. Disconnect cruise control module connecter terminal "K" (Dark Green wire). Backprobe cruise control module connector with voltmeter between terminal "K" (Dark Green wire) and ground. Turn ignition on. Set cruise control switch ON. If voltage is about 5 volts, check for poor connection at terminal "K". If connection is okay, replace cruise control module. If voltage is not about 5 volts, check for short to ground or open circuit in Dark Green wire. Also check for poor connection at cruise control module connector terminal "K". If wiring and connection are okay, replace cruise control module.
9. Reconnect cruise control connector. Set parking brake. Start engine. Move cruise switch to OFF position, then move switch to ON position. Wait 3 seconds, then go to next step.
10. Fully depress and hold brake pedal. Push cruise SET switch in and hold. Hold cruise switch in R/A position. After 10 seconds, release brake pedal while still holding R/A and set switches.
11. If engine RPM momentarily increases, check is speed sensor signal is correctly reaching cruise control system at cruise control module terminal "K" (Dark Green wire). If engine RPM does not momentarily increase, replace cruise control module.

CRUISE CONTROL WILL NOT RESUME, ACCELERATE, TAP-UP, OR TAP

DOWN

1. Turn ignition on. Turn cruise control switch to ON position. Backprobe multifunction lever connector with a test light between connector terminal E4 (Gray/Black wire) and ground. (Scheme 2) Press RESUME/ACCEL switch.
2. If test light lights, check for poor connection or open circuit in Gray/Black wire. Also check for poor connection at cruise control module terminal "C" (Gray/Black wire). If all connections are wiring are okay, replace cruise control module. If test light does not light, check for poor connection at multifunction lever connector or open circuit in steering column harness. Also check for poor connection at steering column harness-to-cruise switch connector. If connection is okay, replace multifunction lever.

Scheme 1

Scheme 2

TROUBLE SHOOTING

Ensure cruise control module linkage is connected and moving freely. Check for a broken or partially broken wire inside insulation which could cause system malfunction but prove good in a continuity/voltage check with system disconnected.

REMOVAL & INSTALLATION

Disconnect negative battery cable. Remove electrical connectors from switch. Remove switch from retainer. Remove retainer from pedal support bracket (if equipped). To install, reverse removal procedure. Adjust switch. See BRAKE & CLUTCH RELEASE SWITCHES ADJUSTMENT under.

Disconnect negative battery cable. Remove bolts and screws securing module. Disconnect electrical connectors. Remove module. To install, reverse removal procedures.

1. Disconnect negative battery cable. Remove steering column housing cover end cap by pulling toward front of vehicle. Disconnect multifunction lever connector at base of steering wheel.
2. Ensure all lever switches and controls are in OFF position. Pull multifunction lever straight out toward driver door to release. Remove multifunction lever. To install, reverse removal procedure.

Disconnect negative battery cable. Raise vehicle. Disconnect speed sensor electrical connector. Remove speed sensor housing cover bolts, cover and gasket. Remove spring washer, washers, magnet, coil assembly and "O" ring together as an assembly. To install, reverse removal procedure.

See also:
• COMPUTER RELEARN PROCEDURES
• BRAKE & CLUTCH RELEASE SWITCHES ADJUSTMENT