CUSTOM CRUISE III TROUBLE SHOOTING/DIAGNOSIS

SOME 1984 CUSTOM CRUISE III (K34) OWNER COMMENTS CONDITION - INOPERATIVE SYSTEM CAUSE - NO POWER TO MODULE TERMINALS "G" AND "A". CORRECTION - CHECK FUSE, BRAKE AND CLUTCH SWITCHES, TURN SIGNAL HANDLE, PINCHED WIRES IN STEERING COLUMN.

CONDITION - INOPERATIVE SYSTEM CAUSE - OPEN "GROUND" AT MODULE TERMINAL "J", SERVO TERMINAL "C", OR VSS GROUND. CORRECTION - REPAIR GROUND CIRCUIT, (RUN NEW GROUND IF NECESSARY).

CONDITION - INOPERATIVE SYSTEM CAUSE - OPEN SPS CIRCUIT (MODULE-SERVO LEADS F-B, H-D OR SPS COIL IN SERVO). CORRECTION - REPAIR LEADS AND/OR REPLACE SERVO.

CONDITION - INOPERATIVE SYSTEM CAUSE - VAC RELEASE VALVE CIRCUIT OPEN TO ATMOSPHERE. CORRECTION - ADJUST OR REPLACE VACUUM RELEASE VALVE, CHECK HOSES, OR REPAIR CIRCUIT.

CONDITION - INOPERATIVE SYSTEM CAUSE - NO HIGH AND LOW VOLTAGE SIGNAL AT MODULE SPEED SENDER TERMINAL "D". CORRECTION - CHECK FOR OPEN LEADS OR BAD BUFFER AMPLIFIER OR SPEEDOMETER. CHECK GROUND AND B+ INPUT.

CONDITION - INOPERATIVE SYSTEM CAUSE - NO 12 VOLT SIGNAL AT MODULE "SET/COAST" TERMINAL "L". CORRECTION - CHECK FOR OPEN LEAD OR CONNECTOR OR BAD TURN SIGNAL HANDLE. CHECK FOR TERMINAL IN PROPER CAVITY.

CONDITION - INOPERATIVE SYSTEM CAUSE - NO VACUUM AT SMALL HOSE TO SERVO. CORRECTION - CHECK FOR PLUGGED, PINCHED, DISCONNECTED VAC HOSES, INCORRECTLY POSITIONED 3 WAY CHECK VALVE, RESTRICTED ENGINE VACUUM FITTING.

CONDITION - INOPERATIVE SYSTEM CAUSE - COCKED SERVO POSITION ROD AND SPRING. CORRECTION - REPLACE SERVO.

CONDITION - INOPERATIVE SYSTEM CAUSE - LEAKY SERVO AND/OR INOPERATIVE VALVES. CORRECTION - REPLACE SERVO.

CONDITION - INOPERATIVE SYSTEM CAUSE - DISCONNECTED SERVO LINKAGE. CORRECTION - RECONNECT.

CONDITION - INOPERATIVE SYSTEM CAUSE - INOPERATIVE MODULE. CORRECTION - REPLACE MODULE.

CONDITION - VEHICLE SURGES CAUSE - EXCESS SLACK IN SERVO LINKAGE. CORRECTION - ADJUST.

CONDITION - VEHICLE SURGES CAUSE - DRY SPEEDOMETER CABLE. CORRECTION - LUBRICATE.

CONDITION - VEHICLE SURGES CAUSE - SPIKES ON B+ LINES. CORRECTION - FIND CAUSE AND REPAIR.

CONDITION - VEHICLE SURGES CAUSE - TURN SIGNAL OR OTHER ELECTRICAL DEVICE INTERFERENCE. CORRECTION - REPOSITION ELECTRICAL LEADS AWAY FROM CRUISE OR VSS BUFFER LEADS. CHECK FOR POOR GROUND AT MODULE, SERVO, OR VSS BUFFER.

CONDITION - VEHICLE SURGES CAUSE - RESTRICTED (KINKED OR LEAKING) VACUUM SUPPLY HOSE TO ACCUMULATOR OR SERVO. CORRECTION - INSPECT HOSES AND REPOSITION AS REQUIRED.

CONDITION - VEHICLE SURGES CAUSE - CROSSED VAC AND VENT ELECTRICAL LEADS BETWEEN MODULE AND SERVO CORRECTION - REWIRE.

CONDITION - VEHICLE SURGES CAUSE - BINDING SERVO BOWDIN CABLE. CORRECTION - REPLACE.

CONDITION - VEHICLE SURGES CAUSE - TORQUE CONVERTER CLUTCH CUTTING IN AND OUT. CORRECTION - NORMAL (NOT A CRUISE PROBLEM).

CONDITION - VEHICLE SURGES CAUSE - INTERMITTENT GROUND. CORRECTION - CHECK FOR POOR GROUND AT SERVO, MODULE, VSS BUFFER. (GENERALLY THIS IS A COMMON GROUND AT THE I.P. OR SERVO.)

CONDITION - VEHICLE SURGES CAUSE - SERVO VALVES STICKING. CORRECTION - REPLACE SERVO.

CONDITION - VEHICLE SURGES CAUSE - INOPERATIVE MODULE. CORRECTION - REPLACE MODULE.

CONDITION - CRUISE SET SPEED HIGH OR LOW CAUSE - EXCESS SLACK IN SERVO LINKAGE. CORRECTION - ADJUST.

CONDITION - CRUISE SET SPEED HIGH OR LOW CAUSE - INCORRECT MODULE PART NUMBER USAGE. CORRECTION - MAKE CORRECTION.

CONDITION - CRUISE SET SPEED HIGH OR LOW CAUSE - INOPERATIVE MODULE. CORRECTION - REPLACE.

CONDITION - NO RESUME FUNCTION CAUSE - INCORRECTION 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.) CORRECTION - ADVISE OPERATOR.

CONDITION - NO RESUME FUNCTION CAUSE - OPEN CONNECTION AT TERMINAL "A" OF MODULE OR TERMINAL IN WRONG CAVITY. CORRECTION - REPAIR.

CONDITION - NO "TAP DOWN" FUNCTION CAUSE - INCORRECT OPERATOR TECHNIQUE. (TAP DOWN HELD DOWN IN EXCESS OF .4 SECOND.) CORRECTION - ADVISE OPERATOR.

CONDITION - NO "TAP DOWN" FUNCTION CAUSE - INCORRECT MODULE USAGE. CORRECTION - MAKE CORRECTION.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - CROSSED VAC AND VENT WIRES. CORRECTION - REWIRE.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - INOPERATIVE TURN SIGNAL MODE CONTROL SWITCH. CORRECTION - REPLACE.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - STICKING VALVES IN SERVO. CORRECTION - REPLACE SERVO.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - BINDING THROTTLE LINKAGE. CORRECTION - MAKE CORRECTION.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - INOPERATIVE MODULE. CORRECTION - REPLACE MODULE.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - INCORRECT MODULE USAGE. CORRECTION - MAKE CORRECTION.

CONDITION - VEHICLE CRUISES OR RESUMES BEYOND SET SPEED CAUSE - INOPERATIVE SPEED SENSOR BUFFER. CORRECTION - REPLACE BUFFER.

CONDITION - CRUISE DROPS OUT WHILE TAPPING DOWN CAUSE - INOPERATIVE MODULE. CORRECTION - 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.