TB12 - Check For Intermittent Circuit Fault

- Key "ON", engine "OFF".

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

- Cycle the 4x4L switch to "4x2".

- Verify 5.0 volts between test pin 42 and test pin 40/60 at the breakout box.

- Grasp the harness starting at the transfer case vehicle harness connector. Shake and bend a small section of the harness all the way to the generic electronic module.

- Tap, shake the vehicle harness connector at the transfer case.

- Shake and bend a small section of the harness between the generic electronic module and the PCM connector.

- Is the voltage reading fluctuating?

Yes -- Isolate fault and service as necessary. Remove breakout box. Connect all components. Rerun quick test. Quick Test Appendix (Detailed Testing Instructions)

No -- Go to TB13. TB13 - Check Continuity of 4X4L Wire