General System Description

This vehicle does not use a conventional Vehicle Speed Sensor (VSS). Instead, a reading from the transmission Output Speed Sensor is sent to the Transmission Control Module (TCM), which then calculates the vehicle speed.

In prior model years, different sized speedometer pinion gears were required because of various vehicle options that include final drive ratio (FDR) and tire sizes. The TCM is capable of replacing the vehicle speed sensor. A pinion factor is stored in the TCM in order to provide the appropriate distance pulses for a vehicle. For 41TE vehicles, the pinion factor is programmed into the TCM at the assembly plant.

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 will not have speedometer operation.
- If a TCM is removed from one vehicle and placed on another, the pinion factor must be reprogrammed according to the new vehicle's FDR and tire size.

NOTE: Swapping of production TCMs is not a recommended procedure.

- Selecting the wrong FDR or tire size may cause the speedometer accuracy to fall out of specification.

PROGRAMMING THE PINION FACTOR
1. With the DRB, move through the program down to the 41TE system menu.
2. Select the "Miscellaneous" function.
3. Select the "Pinion Factor" function.
4. Select the appropriate tire size.
5. Verify speedometer operation.