Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Pinpoint Test C : TCS (Transmission Control Switch) (O/D Cancel) Circuit Out Of Self Test Range: Notes
Refer to Transmission Controls - 6R100 for schematic and connector information. Refer to Transmission Controls - TorqShift 6 for schematic and connector information.
Normal Operation and Fault Conditions
The Tow/Haul select switch is a momentary contact switch located on the end of the selector lever. Pressing the Tow/Haul switch will engage or disengage the Tow/Haul function of the transmission. When the Tow/Haul is engaged, the Tow/Haul icon illuminates on the IPC. Each time the ignition switch is cycled, the PCM/ TCM disengages the Tow/Haul operation regardless of the switch position the last time the engine was running.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P1780 | Transmission Control Switch (O/D Cancel) Circuit Out of Self-Test Range | The Tow/Haul select switch failed during the KOER self-test. |
Possible Sources
- Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
- BCM fuse 19 (7.5A)
- TCS
- PCM
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.