P079C
DTC P079C
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P079C
- Transmission Clutch 3 Slip Detected
Typical Scan Tool Data
Circuit/System Description
The transmission control module (TCM) monitors the Clutch Slip 3 Speed for each Hybrid Transmission Mode Commanded state. The TCM is part of the control solenoid valve assembly and is not serviced separately.
Conditions for Running the DTC
* The clutch pressure control solenoid 3 commanded pressure is 1800 kpa (261 psi) for 1 second.
* Clutch fill is detected.
* Clutch torque commanded is greater than 50 Nm (37 lb ft).
Conditions for Setting the DTC
* The TCM detects the clutch 3 Slip Speed is greater than 300 RPM for greater than 1 second. The TCM retries 3 times at 30 second intervals.
* Motor 1 or 2 are approaching overspeed limits due to clutch slip, the fault will set instantly.
Action Taken When the DTC Sets
P079C is a Type A DTC.
Conditions for Clearing the DTC
P079C is a Type A 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 Hybrid/EV Battery Pack X1
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearning for scan tool information
Circuit/System Verification
1. Verify that DTC P0721, P0966, P0967, P0969, P0970, P0971, P0973, P0974, P0976, P0977, P215C, P2714, P2715, P2720, P2721, P2728, P2729, or P2730 is not set.
• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
2. Perform the Transmission Fluid Level and Condition Check Testing and Inspection to verify correct fluid level and condition.
3. Perform the Line Pressure Check Line Pressure Check to verify correct oil pressure.
4. Operate the vehicle in LS-ICE mode. The Clutch 3 Slip Speed parameter should be less than 100 RPM when the Clutch 3 Status parameter displays Applied.
Component Testing
1. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection to verify control solenoid valve assembly condition.
2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test to verify control solenoid valve assembly function.
• If a concern is found, replace the Q8 control solenoid valve assembly.
3. Inspect the a/trans fluid level control valve for stuck closed or damaged condition.
• If you found a concern with the a/trans fluid level control valve, replace the a/trans fluid level control valve.
4. Inspect the valve body components and hydraulic circuits listed below for a leak or a stuck valve:
* Control valve body spacer (w/gasket) plate assembly
* 1-3 reverse and drive motor/generator stator cooling regulator valve
* 1-3 reverse and drive motor/generator stator cooling regulator feedback valve
• If you found a concern in the valve body, repair or replace the valve or valve body.
5. Inspect the 1-3 reverse clutch assembly, piston, snap ring, discs, and housing for a damaged condition.
• If you found a 1-3 reverse clutch assembly concern, repair or replace the 1-3 reverse clutch assembly as necessary.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Control Valve Body Replacement Control Valve Body Replacement for control valve body replacement.
* 1-3-Reverse Clutch, Input Clutch Hub, and Hub Shaft Removal 10. 1-3-Reverse Clutch, Input Clutch Hub, and Hub Shaft Removal
* Transmission Replacement Transmission Replacement for Transmission removal
* Control Module References Programming and Relearning for Control Solenoid Valve Assembly and Transmission Control Module Assembly replacement, programming, and setup.
* Perform the Reset Transmission Adapts Programming and Relearning following all transmission related repairs.