OIL PRESSURE GAGE FLUTTERS OR READS HIGH (REPLACE SENSOR)

SUBJECT: OIL PRESSURE GAGE FLUTTERS, OR MAY READ HIGH (REPLACE SENSOR)

MODELS: 1990-91 S/T, M/L, C/K, R/V/G/P

THIS BULLETIN CANCELS AND REPLACES GMC TRUCK BULLETIN 91-6A-157, PUBLISHED IN NOVEMBER 1991. IT WAS REVISED TO UPDATE PART NUMBER INFORMATION FOR P-TRUCKS AND DIESEL ENGINES. ALL COPIES OF 91-6A-157 SHOULD BE DISCARDED.

On S/T, M/L, C/K, R/V, G, and P vehicles with gages, the oil pressure gage may flutter or show unusually high oil pressure (full scale), because the internal resistance wire in the sensor may not be properly supported, resulting in an intermittent open condition.

SERVICE PROCEDURE:

Check for normal causes of high oil pressure gage readings (high resistance or open circuit), such as a poor ground path caused by loose sensor mount- ing, oil cooler adapter loose, or poor electrical connections. If no cause can be found, replace the oil pressure sensor with the correct new part number from the chart below.

SERVICE PARTS INFORMATION:

NEW OIL PRESSURE SENSOR PART NUMBERS: 1990-91 Models

Model Engine(s) VIN Codes New P/N ----- --------- --------- ------- M/L All B,Z 10096178 S/T LN8/L38 A,E 10096178 S/T LB4/LL2 Z,R 10096179 C/K All Gas All 10137652 C/K Diesel C,J 15564999 R/V All Gas All 10137652 R/V Diesel C,J 15564999 G All Gas All 10137652 G Diesel C,J 15591103 P (91) All Gas All 10096178 P (90) All Gas All 10137652 p Diesel C,J 15591103

For further details, refer to GMC Truck Bulletin 92-8C-30, published January 1992.

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

Use existing labor operation N2220.

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.