INCORRECT/ERRATIC OIL PRESSURE READINGS INST OIL PRESS SENSOR

SUBJECT: INCORRECT OR ERRATIC OIL PRESSURE READINGS

MODEL and YEAR: 1990-93 ALL LIGHT DUTY TRUCKS

Owners of some 1990 through 1993 light duty trucks may comment that the oil pressure dash gage reads high, has erratic movement or is inoperative.

The internal resistance wire in the oil pressure 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 mounting, oil cooler adapter loose, or poor electrical connections. If no cause can be found, replace the oil pressure sensor following the procedure below.

1. Disconnect the negative battery cable.

2. Remove the wiring harness connector from the oil pressure sensor.

3. Remove the oil pressure sensor.

4. Install the new oil pressure sensor.

5. Connect the wiring harness connector to the oil pressure sensor.

6. connect the negative battery cable.

Parts Information:

. New Oil Pressure Sensor Part Numbers for the 1990-1993 models are:

Engine Model Engine(s) VIN Codes New P/N Replaces ----- --------- --------- ------- -------- 10201490 1647135-90/91 S/T L38/LN8/L35 A,E,W 10201490 10096178-92/93

10201491 1647136-91/92 LL2/LB4 R,Z 10201491 10096179-92/93

10201490 1647135-90/91 WL LN8/L35/LB4 E,W,Z 10201490 10096178-92/93

Engine Model Engine(s) VIN Codes New P/N Replaces ----- --------- --------- ------- -------- 10201489 10068563-90/91 C/K All Gas Z,H,K,N 10201489 10137652-92/93 10201489 10068563-90/91 G All Gas Z,H,K,N 10201489 10137652-92/93 10201489 10068563-90/91 R/V All Gas K,N 10201489 10137652-92/93 10201489 10068563-90/91 P (60 psi) All Gas Z,K,N 10201489 10137652-92/93 P (80 psi) All Gas Z,K,N 10201490 10096178-92/93

Parts are currently available from GMSPO

Warranty Information:

For vehicles repaired under warranty use 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.