ERRATIC ENGINE OIL PRESSURE NEW DESIGN SENDER AVAILABLE

REVISION: 03/15/94

THIS BULLETIN IS BEING REVISED TO ADD P6 AND B7 MODELS, ADD 1992-94 MODELS YEARS AND TO CHANGE THE PART NUMBERS. PREVIOUS DIVISIONAL PUBLICATION NUMBERS WERE:

DIV BULLETIN # DATE PUBLISHED

GMC TRUCK 91-6D-40 12/10/90 GM CANADA 90-8-501 2/27/91 ----------------------------------------------------------------------

SUBJECT: ERRATIC ENGINE OIL PRESSURE GAUGE READINGS-ENGINE OIL PRESSURE SENDING UNIT INOPERATIVE (REPLACE SWITCH)

MODELS: 1990-94 CHEVROLET AND GMC TRUCK 6H, 7H, P6, AND B7

CONDITION:

SOME OWNERS MAY EXPERIENCE ERRATIC ENGINE OIL PRESSURE GAUGE READINGS.

CAUSE:

INTERNAL SENSITIVITY OF ORIGINAL SWITCH.

CORRECTION:

IN MOST CASES, THIS CONDITION CAN BE CORRECTED BY REPLACING THE ENGINE OIL PRESSURE SENDING SWITCH WITH A NEW DESIGN SWITCH.

VEHICLES INVOLVED:

THE NEW DESIGN ENGINE OIL PRESSURE SENDING SWITCH WAS INSTALLED AT THE START OF PRODUCTION IN JULY 1992.

SERVICE PROCEDURE:

1. DISCONNECT THE WIRING CONNECTOR FROM THE ENGINE OIL PRESSURE SENDING SWITCH (SEE FIGURE 1).

2. BEFORE REMOVING THE OIL PRESSURE SENDING SWITCH, MAKE SURE THAT THE ENGINE IS COLD TO AVOID POSSIBLE CONTACT WITH HOT ENGINE OIL. PLACE A DRAIN PAN UNDER THE ENGINE TO CATCH THE OIL LOSS WHEN THE SWITCH IS REMOVED.

3. REMOVE THE ENGINE OIL PRESSURE SENDING SWITCH FROM THE ENGINE.

4. APPLY THREAD SEALANT (GM PART #12345579 OR EQUIVALENT) TO THE THREADS OF THE NEW OIL PRESSURE SENDING SWITCH.

5. INSTALL THE OIL PRESSURE SENDING SWITCH INTO THE ENGINE BLOCK. TIGHTEN THE SENDING SWITCH TO 13 N.M (10 LBS. FT.).

6. CONNECT THE WIRING CONNECTOR.

IMPORTANT: BE SURE TO CHECK THE OIL LEVEL, AND FILL TO THE PROPER LEVEL AFTER THE SENDING SWITCH REPLACEMENT PROCEDURE IS FINISHED.

7. START THE ENGINE AND VERIFY PROPER ENGINE OIL PRESSURE GAGE OPERATION (MEDIUM TRUCK SERVICE MANUAL, SECTION 8C).

SERVICE PARTS INFORMATION:

PART NUMBER DESCRIPTION

15955709 SWITCH ASSEMBLY-GAS ENGINE OIL PRESSURE INDICATOR 15955710 SWITCH ASSEMBLY-DIESEL ENGINE OIL PRESSURE INDICATOR 1052080 SEALANT

PARTS ARE CURRENTLY AVAILABLE FROM GMSPO.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY USE:

LABOR OP DESCRIPTION LABOR TIME

N2220 SWITCH-REPLACE, ENGINE OIL PRESSURE USE PUBLISHED LABOR OPERATION TIME

FIGURES: 01

CAPTIONS: FIGURE 1 - LOCATION FOR OIL PRESSURE SENDING SWITCH (USE ORIGINAL ARTWORK)

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.

COPYRIGHT 1994 GMC TRUCK DIVISION, GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.