TB20 - Check Transmission Control Switch Module

- Key "OFF".

- Breakout box installed, Powertrain Control Module (PCM) disconnected.

- Access the Transmission Control Switch Module (TCSM) harness connector.

- Remove TCSM from its mounting location to gain access to harness connector.

- Key on engine "OFF".

- Measure the voltage between the orange/black wire and the black/white wire of the TCSM connector while cycling the Transmission Control Switch (TCS) several times.

- Does the voltage cycle?

Yes -- Service the open circuit from the TCSM connector to PCM. Check orange/black wire to test pin 41. Check black/white wire to test pin 40/60. Reconnect PCM. RERUN Self-Test.

NOTE: If voltage cycles and the TCIL does not Go to TB25. TB25 - Transmission Control Indicator Light Never On

No -- Go to TB21. TB21 - Check Wiring of Transmission Control Switch Module