TG101 - Check Continuity of Sensor Harness SIG RTN Circuit

Diagnostic Trouble Code (DTC) 668 indicates the Transmission Range (TR) circuit voltage was above the allowed maximum voltage.

Possible causes:
- Open in TR harness SIG RTN circuit.
- Damaged TR sensor.
- Damaged Powertrain Control Module (PCM).
- Short to power in TR harness SIG circuit.

- Key "OFF".

- Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion or loose wires, etc. Service as necessary.

- Disconnect TR sensor.

- Using a mirror, inspect both ends of transmission harness connector at TR sensor for damaged or pushed out pins, corrosion or loose wires, etc. Service as necessary.

- Install breakout box, leave PCM disconnected.

- Measure resistance between test pin 46 at the breakout box and SIG RTN circuit at the TR sensor vehicle harness connector.

- Is resistance less than 5.0 ohms?

Yes -- Go to TG102. TG102 - Check For Short to Power In Signal Circuit

No -- Service open circuit. Remove breakout box. Reconnect all components. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)