P079C

DTC P079C

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.



DTC Descriptor
DTC P079C
- Transmission Friction Element 3 Slip Detected




Typical Scan Tool Data






Circuit/System Description

The transmission control module (TCM) monitors the Clutch Slip for each Hybrid Trans. Mode Commanded state. This DTC detects clutch slip when the 4th clutch is commanded ON, indicating a slipping clutch condition.


Conditions for Running the DTC

* 4th clutch is the primary on-coming clutch.
* The commanded gear is 4.



Conditions for Setting the DTC

* 4th clutch is the primary on-coming clutch.
* The commanded gear is Gear 4.



Action Taken When the DTC Sets

DTC P079C is a Type B DTC.


Conditions for Clearing the DTC

DTC P079C is a Type B DTC.


Diagnostic Aids

When attempting to set transmission performance DTCs, observe the Freeze Frame and Failure Records to assist in duplicating the failure conditions. Ensure the transmission fluid level is correct and there are no leaks. If there are any other transmission DTCs set, diagnose those first.


Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views
Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs
* High Voltage Disabling
* High Voltage Enabling

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions


Circuit/System Verification

1. Clear the DTC.
2. Operate the vehicle to induce a shift from 3rd to 4th gear while observing the 4th Clutch Slip parameter. Stop the vehicle and turn the ignition OFF for 30 seconds. Perform this action 2 times. The 4th Clutch Slip parameter should display 0 RPM when the 4th Clutch Status parameter displays Applied.

• If any other DTCs set, diagnose that DTC first.
• If DTC P079C resets, go to Component Testing.




Component Testing

1. Perform the Line Pressure Check (Line Pressure Check) .
2. Inspect the trans fluid pump ball check valve for possible sticking or damage.

• If you found a concern with this check ball, repair the concern.

3. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test (Control Solenoid Valve and TCM Assembly Solenoid Performance Test) .

• If a concern is found, replace the control solenoid (w/body and TCM) valve assembly.

4. Inspect the hybrid low, 1-2 clutch boost valve assembly and the hybrid low, 1-2 clutch regulator valve assembly for sticking or damage.

• If you found a concern with the hybrid low, 1-2 clutch boost valve assembly or the hybrid low, 1-2 clutch regulator valve assembly, repair or replace the valve or valve body.

5. Inspect the 4th clutch assembly for a slipping or damaged condition.

• If you found a 4th clutch assembly concern, repair or replace the low and reverse clutch assembly as necessary.




Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* 4th clutch assembly replacement. Refer to Clutch 4 Overhaul .
* Lower valve body assembly repair or replace. Refer to Control Valve Body Replacement (Control Valve Body Replacement) .
* Perform the valve body inspection procedure, refer to Control Valve Upper Body Assembly Cleaning and Inspection . If the inspection procedure indicates to replace the valve body, refer to Control Valve Lower Body and Upper Body Replacement .
* Control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References for replacement, setup, and programming.