TB8 - Check Continuity of Control Switch Harness

- Key "OFF".

- Breakout Box connected, Powertrain Control Module (PCM) disconnected.

- Appropriate switch disconnected.

- For 4x4 Low circuit:

- Measure the resistance between test pin 12 (multiport fuel injection vehicles) or test pin 42 (sequential fuel injection vehicles) at the breakout box and 4x4 Low circuit at 4x4 Low switch touch drive module vehicle harness connector.

NOTE: Sequential fuel injection vehicles may be easily identified by their use of a Mass Air Flow (MAF) sensor while multiport fuel injection vehicles use a Manifold Absolute Pressure (MAP) sensor.

- For Transmission Control Switch (TCS) / Transmission Control Indicator Lamp (TCIL) circuit:

- Measure the resistance between keypower at the fuse panel (fuses) (ohmmeter positive probe) and power side of transmission control switch vehicle harness connector (ohmmeter negative probe).

- Measure the resistance between test pin 41 at the breakout box and signal side of transmission control switch vehicle harness connector.

- Are both resistances less than 5.0 ohms?

Yes -- Go to TB9. TB9 - Check Harness Circuit(s) For Shorts to Power

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