Transmission Mode Switch C Circuit

Where it lives

For P078F, the switch sits on the circuit this code reports. The description of P078F reports a fault at the switch.

Check these first

• A faulty transmission mode switch C
• An open in the mode switch C wiring to the ECM
• A short in the mode switch C circuit
• Corrosion at the mode switch C connector
• An ECM fault on the mode switch input

What to do next

1. Read the mode switch C state on a scan tool
2. Test the mode switch C circuit for an open or short
3. Measure switch resistance in each position
4. Check the connector and wire harness
5. Replace the switch if the circuit tests good
6. Clear the code and retest

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