Electronic Pinion Factor

The transmission output speed signal supplies distance pulses to the Powertrain Control Module (PCM), which are used to calculate speed and mileage. A pinion factor is stored in the Transmission Control Module (TCM) in order to provide the appropriate distance pulses for the vehicle. The pinion factor is programmed into the TCM at the assembly plant.

Using the following steps, the pinion factor can be checked and/or reset using the DRB:

1. Select "Transmission" system, then "Miscellaneous" functions, then "Pinion Factor", The DRB will display the current tire size.

2. If the tire size is incorrect, depress the Enter key and then select the correct size.

3. Depress the Page Back key to exit the reset procedure.

Notes About Electronic Pinion Factor Features
The nature of the electronic pinion factor requires that certain features must be taken into consideration:

- If no pinion factor is stored in an installed TCM, the vehicle speedometer will not operate, engine speed will be limited to 2,300 RPM, and catalyst damage may occur.

- If a TCM is removed from one vehicle and placed in another, the pinion factor must be reprogrammed according the new vehicle's final drive ratio (FDR) and tire size.

NOTE: Swapping of production TCM's is not a recommended procedure.

- Selecting a wrong FDR or tire size will cause the speedometer to be inaccurate and will also cause any speed related features to operate improperly.