Pinion Factor Writing Procedure

NOTE: Use this procedure after Transmission Control Module (TCM) replacement or tire size change.

With F4AC1 transmissions, the TCM uses the rotation speed of the transaxle output shaft to calculate the vehicle speed and cumulative distance travelled. Because of this, it is necessary to input (or update) the tire size coefficient into the TCM memory after the TCM has been replaced or the tire size has been changed.
- Select "Special function" on the scan tool and then set the scan tool to Pinion Factor mode (carry out this operation from the scan tool screen). Then input (or update) the tire size coefficient into the TCM memory. Note that new TCMs do not have a tire size coefficient already input.