P1779
DTC P1779
Circuit Description
Vehicles currently using the 8.1 liter gas engine use a 3 wire system to communicate engine torque data/requests between the engine control module (ECM) and the transmission control module (TCM).
DTC P1779 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1779 Engine Torque Delivered to Transmission Control Module (TCM) Signal
Conditions for Running the DTC
* The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
* Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.
Conditions for Setting the DTC
DTC P1779 sets if managed engine torque, net, signal is less than 1.5 percent or greater than 98.5 percent for greater than 2 seconds.
Action Taken When the DTC Sets
* The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
* DTC 1779 is stored in TCM history.
* The TCM defaults to a calculated managed torque, net, input value using throttle and engine speed.
* The TCM defaults to a calculated unmanaged torque, gross, input value using throttle and engine speed.
* The TCM inhibits torque converter clutch (TCC) engagement.
Conditions for Clearing the DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
* Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions:
- A bent terminal
- A backed-out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation
* When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
* You may have to drive the vehicle in order to experience a condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step tests for a damaged terminal or connector.
4. This step tests for an open/short.
