CUSTOM CRUISE III TROUBLE SHOOTING/DIAGNOSIS. GMC Truck Caballero 1984

For 1990-2009 cars

# CUSTOM CRUISE III TROUBLE SHOOTING/DIAGNOSIS

#### MODELS: 1984 MODELS WITH CUSTOM CRUISE III (K34)

CONDITION CAUSE CORRECTION

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

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

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

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

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

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

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

Cocked servo position rod and Replace servo. spring.

Leaky servo and/or inoperative Replace servo. valves.

Disconnected servo linkage. Reconnect.

Inoperative module. Replace module.

Vehicle Excess slack in servo linkage. Adjust. Surges Dry speedometer cable. Lubricate.

Spikes on B+ lines. Find cause and repair.

Turn signal or other Reposition electrical electrical device leads away from cruise interference. or VSS buffer leads. Check for poor ground at module, servo, or VSS buffer. Restricted (kinked or Inspect hoses and leaking) vacuum supply reposition as required. 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 bufter. (Generally this is a common ground at the I.P. or servo.)

Servo valves sticking. Replace servo.

Inoperative module. Replace module.

Cruise Set Excess slack in servo Adjust. Speed High linkage. or Low Incorrect module part Make correction. number usage.

Inoperative module. Replace.

No Resume Incorrect operator technique. Advise operator. Function (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 Incorrect operator technique. Advise operator. down" (Tap down held down in excess Function of .4 second.)

Incorrect module usage. Make correction.

Vehicle Crossed vac and vent wires. Rewire. Cruises or Resumes Beyond Set Speed 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 buffer. Replace buffer.

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

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.