Pinpoint Test C : DTC (Diagnostic Trouble Code) P1780: Notes
DTC P1780
Refer to Wiring Diagrams TRANSMISSION CONTROLS - 6R80 for schematic and connector information.
Normal Operation
The transmission control switch is a momentary contact switch located on the selector lever. When the switch is pressed the contacts close sending a voltage signal to the PCM (3.5L, 3.7L engine) or TCM (3.2L diesel). The transmission control switch is hardwired to the PCM/ TCM and notifies the module to disable the overdrive gear. The PCM/ TCM sends a message over the MS-CAN to the IPC which illuminates the tow haul indicator light in the IPC. When the switch is depressed again the PCM/ TCM enables the overdrive gear in the transmission and sends a message to the IPC extinguishing the tow haul light.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P1780 | Transmission Control Switch (O/D Cancel) Circuit Out of Self-Test Range |
NOTE:
For vehicles not equipped with a tow haul switch, disregard this DTC. This DTC sets when the PCM / TCM does not see a change on the transmission control switch circuit during the KOER on-demand self-test. |
Possible Sources
- Circuitry open/shorted
- Transmission control switch
- PCM (3.5L, 3.7L engine)
- TCM (3.2L diesel)