P1780

DTC P1780

Circuit Description

The transmission control module (TCM) is an electronic device which monitors inputs to control various transaxle functions, including shift quality and transaxle sensors, switches, and components to process for use within the control program. Based on this input information, the TCM controls various transaxle output functions and devices.

Information is transmitted between the TCM and engine control module (ECM) through the controller area network (CAN). Information is as follows:

* Engine malfunction signal
* Engine speed
* Engine output torque reduction signal
* Engine coolant temperature

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1780 Torque Reduction Signal

Conditions for Setting the DTC

* The engine speed is greater than 7,000 RPM.
* System voltage is too high or too low.
* CAN transmitting wiring harness shorted or open
* The TCM or ECM is defective.
* Immediately after the above condition occurs.

Action Taken When the DTC Sets

* No lamp control required, but diagnostic information should be stored immediately when the malfunction is detected.
* Adopt Emergency/Substitute mode and constant 4th gear.
* Open lock up clutch.

Conditions for Clearing the Hold Lamp/DTC

Using a scan tool can clear history DTCs.

Diagnostic Aids

* Inspect the poor wiring harness connection for TCM connectors and transaxle wiring connectors.
* Inspect the improperly formed or damaged terminals.