INFO ON SHIFT INDICATOR LIGHT APPLICATION AND OPERATION

Subject: SHIFT INDICATOR LIGHT APPLICATION AND OPERATION

Model and Year: 1992 C/K AND P TRUCKS WITH 4.3L ENGINE AND MANUAL TRANSMISSION

Certain 1992 C, K and P 4.3L trucks do not make use of a shift indicator light:

- The shift light is commonly used to achieve improved fuel economy, by prompting the driver when to upshift.

Depending on which prom calibration is installed in the ECM/PCM, the shift light can have the following characteristics:

- Indicates proper shift point for maximum fuel economy.

- Indicates engine over-rev (above 4000 rpm).

- Shift light is inoperative.

Use following chart to determine normal shift light operation for the vehicle in question:

TRANS RPO FUEL ECONOMY GVW SERIES SHIFT LIGHT SHIFT LIGHT OVER REV ---- ------ ----------- ------------ -------- (8500 GVW C MG5 YES YES (8500 GVW C MT8 NO YES (8500 GVW K MG5 NO YES (8500 GVW K MT8 NO YES OVER 8500 GVW C,K,P MT8 NO NO OVER 8500 GVW CKP M20 NO NO

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.