TE20 - Attempt To Generate DTC 56 or 637

Diagnostic Trouble Code (DTC) 66 and 638 indicate that Transmission Fluid Temperature (TFT) sensor output was less than the allowed Self-Test minimum value of 0.15 volts.

Possible causes:
- Fluid levels not to specification.
- Damaged TFT sensor.
- TFT shorted to ground.
- Damaged Powertrain Control Module (PCM).

- Key "OFF".

- Disconnect transmission connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.

- Run Key On Engine Off (KOEO) Self-Test (transmission connector remains disconnected for KOEO Self-Test). Quick Test Appendix (Detailed Testing Instructions)

- Is DTC 56 or 637 present?

NOTE: Disregard any other DTC generated at this time.

Yes -- Refer to Transmission and Drivetrain for TFT sensor service.

No -- Go to TE21. TE21 - Check VREF At the Throttle Position Sensor