VEHICLE SPEED SENSOR CODES AND ERRATIC SPEEDOMETER. GMC Truck Safari

SUBJECT: VEHICLE SPEED SENSOR CODES AND ERRATIC SPEEDOMETER (REPLACE WIRE AND INSULATE)

MODELS: 1993 CHEVROLET AND GMC TRUCK M/L VAN WITH 4.3 ENGINE (VIN Z - RPO LB4), 4L60E TRANSMISSION (M30) BUILT PRIOR TO THE FOLLOWING VIN BREAKPOINTS:

DIVISION VIN CHEVROLET 181368 GMC 531973

CONDITION:

SOME OWNERS MAY EXPERIENCE INOPERATIVE OR ERRATIC SPEEDOMETER (CODE 24 OR 72), THE VEHICLE SHIFTING DOWN INTO SECOND GEAR (CODE 24) OR WILL NOT SHIFT OUT OF SECOND GEAR (CODE 72), AND/ OR THE ANTI-LOCK/ABS LIGHT ILLUMINATES ON THE INSTRUMENT PANEL (CODE 37).

CAUSE:

THE VEHICLE SPEED SENSOR WIRING IS DAMAGED IN THE ENGINE COMPARTMENT BETWEEN THE VALVE COVER AND THE PASS THROUGH BODY CONNECTOR. THE PROTECTIVE COVER AT THIS PORTION OF THE ENGINE HARNESS AND ELECTRICAL CONTROL MODULE HARNESS IS RUBBING THROUGH, THUS ALLOWING THE WIRING HARNESS TO CONTACT THE VALVE COVER AND/OR THE THERMAC HEAT TUBE.

CORRECTION:

REPLACE WIRE ACCORDING TO GUIDELINES FOUND IN THE WIRE REPAIR SECTION OF THE SERVICE MANUAL. CUT CONDUIT TO NEEDED LENGTH. ADDED CONDUIT MUST BE TAPED AT BOTH ENDS TO PROPERLY SECURE IN PLACE. NYLON CONDUIT MATERIAL, .87 - 1.0 INCH (22 MM - 25.4 MM) DIAMETER, CAN BE PROCURED LOCALLY IF BELOW LISTED PART NUMBER IS NOT READILY AVAILABLE.

SERVICE PARTS INFORMATION:

P/N DESCRIPTION QTY

12013948 CONDUIT 1

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OP DESCRIPTION LABOR TIME N6270 WIRING AND/OR CONNECTOR REPAIR, ENGINE USE PUBLISHED LABOR OPERATION TIME

FIGURES: 1

CAPTIONS: FIGURE 1 - ENGINE TRANS. ASSEMBLY WITH HARNESS

Object Number: 84077 Size: FS

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.