1981 DIAGNOSTIC CODES FAULTY CHIP IN CIRCUIT BOARD

THIS BULLETIN CONTAINS MULTIPLE SUBJECT MATTERS OF MISCELLANEOUS ITEMS. PAGE THROUGH TO DESIRED SUBJECT MATTER. 1. DIAGNOSTIC CODES 16, 19 AND 20 -1981 DFI VEHICLES SOME ECM'S MAY PRODUCE INTERMITTENT CODES 16, 19 AND/OR 20 DUE TO AN IMPROPERLY FUNCTIONING CHIP ON THE CENTER PRINTED CIRCUIT BOARD. THESE CODES ARE STORED DUE TO THE ECM'S INCORRECT PROCESSING OF BATTERY VOLTAGE. THIS CONDITION CAN BE OBSERVED BY DISPLAYING THE "BATTERY VOLTAGE" PARAMETER NO 11. THIS VOLTAGE WILL BEGIN TO VARY AS THE CENTER BOARD IS TORQUED. TORQUE CAN BE APPLIED BY MANIPULATING THE RED AND ORANGE ECM CONNECTORS. ECM REPLACEMENT WILL CORRECT THIS CONDITION.

2. OXYGEN SENSOR - ALL DFI AND CCC EQUIPPED CADILLACE

IF ANY OXYGEN SENSOR BOOT BECOMES CAKED WITH MUD OR DIRT, THE SENSOR MAY BECOME INOPERATIVE. SLIDING THE BOOT BACK AND CLEANING MAY RESTORE THE OXYGEN SENSOR TO NORMAL OPERATION.

3. CLEARING CODES - ALL COMPUTER COMMAND CONTROL EQUIPPED VEHICLES

CCC DIAGNOSTIC CODES SHOULD BE CLEARED BY REMOVING THE ECM BATTERY POWER FUSE (10 AMP "ECM1" FUSE ON CIMARRONS AND "BATTERY" FUSE ON 1981-1982 C, E, AND K CARS) WITH THE IGNITION OFF. REMOVING THE FUSE WITH THE IGNITION IN THE RUN POSITION COULD DAMAGE THE ECM.

4. HT4100 FUEL PUMP

THE PN'S FOR HT4100 FUEL PUMPS ARE INCORRECTLY LISTED IN THE 1982 PARTS CATALOG. THE CORRECT P/N'S FOR THE 1982 HT4100 FUEL PUMPS ARE LISTED BELOW. THESE PUMPS HAVE A REVISED CHECK BALL DESIGN AND MAY ALSO BE USED ON 1981 DFI VEHICLES.

MODEL FUEL PUMP P/N 1981-1982 E,K 6472000 1981-1982 C 6472010

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.