For 1990-2009 cars

DTC | DTC Parameters | Diagnosis
--- | --- | ---
P1779 Engine Torque | DTC P1779 sets if the TCM receives an invalid engine torque signal from the ECM. The TCM will inhibit adaptive learning and default to maximum line pressure. P1779 is a type A DTC. | Check for any DTCs stored in the ECM and EBTCM related to the engine torque circuit and refer to the appropriate diagnostic in the Engine or Brakes service manual.
P1780 Torque Reduction Signal | DTC P1780 sets if the TCM receives an invalid torque reduction signal from the ECM. The TCM will inhibit adaptive learning and default to maximum line pressure. P1780 is a type C DTC. | Check for any DTCs stored in the ECM and EBTCM related to the torque reduction circuit and refer to the appropriate diagnostic in the Engine or Brakes service manual.
P1791 Throttle/Pedal Position Signal | DTC P1791 sets if the TCM receives an invalid throttle position signal from the ECM. The TCM will inhibit adaptive learning and default to maximum line pressure. P1791 is a type A DTC | Check for any DTCs stored in the ECM related to the throttle position circuit and refer to the appropriate diagnostic in the Engine service manual.
P1792 Engine Coolant Signal | DTC P1792 sets if the TCM receives an engine coolant signal from the ECM. P1792 is a type D DTC. | Check for any DTCs stored in the ECM related to engine coolant circuit and refer to the appropriate diagnostic in the Engine Service manual.
P1795 TAC System Signal | DTC P1795 sets if the TCM receives an invalid throttle actuator control system signal from the ECM. P1795 is a type A DTC. | Check for any DTCs stored in the ECM related to the TAC system circuit and refer to the appropriate diagnostic in the Engine service manual.

### Circuit Description

The ECM sends serial data to the TCM via the CAN bus. DTCs 1779-1795 do not indicate a problem with the transmission or with the TCM. IT does indicate that the ECM is not sending the required information to the TCM. Check for any related DTCs stored in the ECM and EBTCM, and refer to the appropriate diagnostic charts in the Engine or Brakes service manual. Clear DTCs in the TCM after a repair is made to the engine or antilock brake system.

### DTC Parameters

DTCs P1779-P1795 set if:

• | The condition exists for longer than 2 seconds.

• | The ignition 1 is 8-18 volts.

• | The engine speed is:

- | MY 2002: 200-7,500 RPM for 5 seconds

- | MY 2003: 500-6,500 RPM for 5 seconds

### Diagnostic Aids

Check for any related DTCs in the ECM and EBTCM, and refer to the appropriate diagnostic charts in the Engine or Brakes service manual.