Action Taken
- PCM turns on the "SERVICE ENGINE SOON" MIL.
- PCM calculates the transaxle input speed based on the output speed and the gear ratio of the gear commanded.
- PCM calculates slip speed from the calculated input speed and engine RPM.
- Torque Converter Clutch (TCC) engaged.
- PCM disables torque management.
- Transaxle shift adapts are maintained at current levels.
- Garage shift adapts are maintained at current levels.
NOTE:
Numbers in list refer to circled numbers in diagnostic flow chart, see Fig 1. For circuit identification see Fig 2.
- With engine idling in PARK or NEUTRAL PD72 should read between 50 and 100 RPM less than engine RPM.
- The transaxle input speed sensor will generate a frequency of greater than 0 Hz when the vehicle is idling. If it does not check CKT 1230, CKT 1231 and speed sensor for open/shorts inside the transaxle.
- Checking CKT 1230 and CKT 1231 for opens or shorts to the PCM. If wire OK, the PCM is faulty.