CUSTOM CRUISE III TROUBLE SHOOTING/DIAGNOSIS

Models Affected: All Equipped With Custom Cruise II

CONDITION CAUSE CORRECTION

Inoperative System No power to module terminals Check fuse, brake and clutch G" and "A". switches, turn signal handle, pinched wires in steering column.

Open "ground" at module Repair ground circuit, (run terminal "J", servo new ground if necessary). terminal "C", or VSS ground.

Open SPS circuit (module Repair leads and/or replace servo leads F-B, H-D or servo. SPS coil in servo).

Vac release valve circuit Adjust or replace vacuum open to atmosphere. release valve, check hoses, or repair circuit.

No high and low voltage Check for open leads or bad signal at module speed buffer amplifier or speed- sender terminal "D". ometer. Check ground and B+ input.

No 12 volt signal at Check for open lead or module set/coast" connector or bad turn signal terminal "L". handle. Check for terminal in proper cavity.

No vacuum at small hose Check for plugged, pinched, servo. disconnected vac hoses, incorrectly positioned 3 way check valve, restricted engine vacum fitting.

Cocked servo position rod Replace servo. and spring.

Left servo and/or Replace servo. inoperative valves.

Disconnected servo Reconnect. linkage.

Inoperative module. Replace module.

Vehicle Surges

Excess slack in servo Adjust. linkage.

Dry speedometer cable. Lubricate.

Spikes on B+ lines. Find cause and repair.

Turn signal or other Reposition electrical electrical device leads away from cruise or interference. VSS buffer leads. Check for poor ground at module servo, or VSS buffer.

Restricted (kinked Inspect hoses and or leaking) vacuum reposition as required. supply hose to accumulator or servo.

Crossed vac and vent Rewire. electrical leads between module and servo.

Binding servo Bowdin cable Replace.

Torque converter clutch Normal (not a cruise cutting in and out. problem).

Intermittent ground. Check for poor ground at servo, module, VSS buffer. (Generally this is a common ground at the I.P. or servo).

Servo valves sticking. Replace servo.

Inoperative module. Replace module.

Cruise Set Speed High or Low

Excess slack in servo Adjust. linkage.

Incorrect module part Make correction. number usage.

Inoperative module Replace.

No Resume Function

Incorrect operator Advise operator. technique. (If R/A held down for more than 1 second, system reverts to accel mode. Speed at time of release is new cruise speed).

Open connection at terminal Repair. "A" of module or terminal in wrong cavity.

No "Tap Down" Function

Incorrect operator Advise operator. technique. (Tap down held in excess of .4 second).

Incorrect module usage. Make correction.

Vehicle Cruises or Resumes Beyond Set Speed

Crossed vac and vent wires. Rewire

Inoperative turn signal mode Replace. control switch.

Sticking valves in servo. Replace servo.

Binding throttle linkage. Make correction.

Inoperative module. Replace module.

Incorrect module usage. Make correction.

Inoperative speed sensor Replace buffer. buffer.

Cruise Drops Out While Tapping Down Inoperative module. Replace module.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.