EXPERTEC TSB (92-7B-99)
Publication date: 1992-06-04Reference number: 92-7B-99
EXPERTEC TSB
TECHNICAL SERVICE BULLETIN
Reference Number(s): 92-7B-99, Date of Issue:
06/04/92
INFO ON SHIFT INDICATOR LIGHT - APPLICATION AND OPERATION
Model(s): 1992 C, K, P TRUCKS WITH 4.3L ENGINE (RPO LB4) AND MANUAL TRANSMISSION
Bulletin No.: GMC 92-7B-99
Date: 06/04/1992
SERVICE INFORMATION
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:
SHIFT LIGHT OPERATION
| GVW | Trans. Series | RPO | Fuel Economy Shift Light | Over Rev. Shift Light |
|---|---|---|---|---|
| Under 8500 GVW | C | MG5 | Yes | Yes |
| Under 8500 GVW | C | MT8 | No | Yes |
| Under 8500 GVW | K | MG5 | No | Yes |
| Under 8500 GVW | K | MT8 | No | Yes |
| Over 8500 GVW | C,K,P | MT8 | No | No |
| Over 8500 GVW | C,K,P | M20 | No | No |