MISC. QUICK SERV. INFO. ITEMS MULTIPLE SUBJECTS

THIS BULLETIN CONTAIN MULTIPLE SUBJECTS. PAGE THROUGH TO DESIRED SUBJECT.

GR. 1 AIR CONDITIONING SYSTEM SERVICE PROCEDURE REVISION, ALL 1981 MODELS

THE EVACUATING PORTION OF THE DISCHARGING, ADDING OIL, EVACUATING AND CHARGING PROCEDURE FOR C.C.O.T. AIR CONDITIONING SYSTEMS HAS BEEN RE- VISED FOR ALL 1981 MODEL CARS.

THE NEW, MORE EFFICIENT PROCEDURE ALLOWS THE A/C SYSTEM TO BE EVACU- ATED ONLY UNTIL THE VACUUM GAGE REACHES 28 OR 29 INCHES OF MERCURY (VACUUM), OR ITS EQUIVALENT AS ADJUSTED FOR ALTITUDE. THIS CHANGE ELIMINATES THE ADDITIONAL 15 MINUTE EVACUATION TIME PREVIOUSLY RE- QUIRED AFTER REACHING THE SPECIFIED MERCURY (VACUUM) LEVEL.

THE NEW PROCEDURE WILL APPEAR IN ALL FUTURE SERVICE MANUAL PUBLICA- TIONS AND THE 1981 LABOR TIME GUIDE WILL BE PUBLISHED WITH A REVISED TIME OF .5 HOURS WHICH REFLECTS THIS PROCEDURE CHANGE.

GR. 6A DIESEL OIL PAN GASKETS

STARTING APPROXIMATELY NOVEMBER 1, 1980, A NEW OIL PAN GASKET WENT INTO PRODUCTION ON DIESEL ENGINES. THIS GASKET IS WIDER BY APPROXI- MATELY 1/4" AND WILL PROTRUDE THIS AMOUNT BEYOND THE OIL PAN FLANGES ALONG EACH SIDE. THIS WILL ALLOW A VISUAL CHECK FOR AN OUT OF PLACE GASKET AFTER THE ENGINE IS ASSEMBLED. PREVIOUS STYLE GASKETS CAN BE USED FOR SERVICE.

GR. 6A V8-6-4 OIL FILTER LEAK CAUSE AND REPAIR

IF YOU ENCOUNTER A 1981 V8-6-4 C-CAR WITH AN OIL LEAK AT THE OIL FILTER, CHECK TO SEE IF THE FILTER IS BULGED OR IF THE GASKET IS PRO- TRUDING FROM BETWEEN THE FILTER AND THE OIL FILTER HOUSING.

IF THIS CONDITION EXISTS, IT IS MOST LIKELY CAUSED BY AN INOPERATIVE OIL PRESSURE RELIEF VALVE IN THE OIL PUMP HOUSING. REPLACE THE OIL PUMP HOUSING ASSEMBLY TO CORRECT THIS CONDITION.

GR. 6C SOME 1981 DFI EQUIPPED CARS WILL NOT PASS DIAGNOSTIC CODES

SOME EARLY 1981 DFI EQUIPPED CARS ORDERED WITHOUT CRUISE CONTROL WILL NOT PASS THE SWITCH TEST (CODE 71) BECAUSE THEY WERE BUILT WITH A NON-CRUISE CONTROL BRAKE SWITCH. THEREFORE, THE WIRES THAT NEED TO BE MOMENTARILY SHORTED TO PASS CODE 71 ARE NOT CONNECTED TO THE SWITCH. YOU CAN, HOWEVER, SHORT THE WIRES MOMENTARILY AT THE APPRO- PRIATE CONNECTOR OR REPLACE THE SWITCH WITH A CRUISE CONTROL BRAKE SWITCH.

1981 DFI EQUIPPED CARS ORDERED WITHOUT CRUISE CONTROL WILL NOT PASS THE CRUISE CONTROL RELATED CODES 76, 77, 78. THE LACK OF A CRUISE CONTROL ON/OFF SWITCH WILL PREVENT ENTERING CODE 90 (ENGLISH DATA) BUT MOMENTARILY SHORTING THE APPROPRIATE CONNECTOR IN THE DASH HAR- NESS WILL GET CODE 90.

1981 DFI EQUIPPED CARS ORDERED WITHOUT REAR DEFOG WILL NOT PASS CODE 80 BECAUSE OF THE LACK OF A REAR DEFOG SWITCH. MOMENTARILY SUPPLY 12 VOLTS TO THE BLUE WIRE IN THE SIX WIRE WEATHERPAC CONNECTOR ON THE POWER MODULE TO PASS CODE 80.

GR. 6C HARD COLD START-DIESEL CARS

SOME DIESEL ENGINE EQUIPPED CARS MAY ENCOUNTER A CONDITION OF HARD COLD STARTS. SHOULD THIS CONDITION EXIST, CHECK THE FUEL PUMP HOUS- ING FOR A CRACK IN THE AREA WHERE THE FUEL LINE IS CONNECTED TO THE FUEL PUMP, WHICH MAY ALLOW AIR TO ENTER THE SYSTEM. THE CRACKED FUEL PUMP HOUSING COULD BE CAUSED BY THE FUEL LINE VIBRATING.

TO CORRECT THIS CONDITION, REMOVE THE RIGHT-HAND THERMOSTAT HOUSING BOLT AND INSTALL A STUD, P/N 6270979. DISCONNECT THE FUEL LINE AT THE FUEL PUMP AND INSTALL A CLIP P/N 343463, ON THE FUEL LINE AS SHOWN IN FIGURE BELOW, THEN INSTALL A WASHER FACE NUT P/N 10008001. REPLACE THE FUEL PUMP AND CONNECT THE FUEL LINE.

GR. 8 C-CAR V-6 WIRING REWORK

A WIRING REWORK WAS INSTITUTED IN PRODUCTION ON 1981 V-6 C-CARS PRIOR TO BROADCAST NO. 105403. THE REWORK INVOLVED THE FOLLOWING CIRCUITS:

- CIRCUIT 411 - LIGHT BLUE WIRE TO FUEL METERING SOLENOID:

- CIRCUIT 496 (DARK BLUE WIRE) AND 452 (452X) (BLACK WIRE) TO THE DETONATION SENSOR.

THE ORIGINAL CONDITION WAS THAT THE INSTRUMENT PANEL HARNESS HAD THESE CIRCUITS WIRED THROUGH THE CENTER BULKHEAD CONNECTOR AND THE ENGINE HARNESS WAS WIRED THROUGH THE ENVIROMENTAL CONNECTOR. CORRECTIONS WERE MADE TWO WAYS: (1) SOME CARS WERE CORRECTED BY MOVING THE WIRES IN THE INSTRUMENT PANEL HARNESS FROM THE CENTER BULKHEAD CONNECTOR. IN EITHER CASE, THE REWORK INVOLVED MATING THESE CIRCUITS THROUGH THE BULKHEAD. WHEN DIAGNOSING THESE CIRCUITS, THEY CAN BE TRACED ON THE CAR FROM THE FUEL METERING SOLENOID AND THE DETONATION SENSOR.

GR. 10 SQUAWK NOISE NEAR WINDSHIELD ON SOME 1981 C-CARS

A SQUAWK FORWARD OF THE WINDSHIELD ON SOME 1981 C-CARS CAN BE CAUSED BY THE REAR HOOD STOPS TOUCHING THE HOOD. APPLY LUBRIPLATE TO ELIMI- NATE THE NOISE.

GR. 10 WINDNOISES AT W/S PILLAR

WINDNOISES ON SOME 1981 C-CARS CAN BE CAUSED BY:

A. FRONT PILLAR VERTICAL DRIP MOLDING HAS POOR FIT TO PILLAR. (SEAL WITH BODY PUTTY, RTV ETC.)

B. LACK OF SEALER AROUND WINDSHIELD GLASS. (ADD CAULK, BODY PUTTY, ETC.)

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.