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 Instructionsprovides an overview of each diagnostic category.
DTC Descriptor
DTC P079C
- Transmission Clutch 3 Slip Detected
Circuit/System Description
The transmission control module monitors the 4th clutch slip Speed when the 4th clutch is applied. The 4th clutch is displayed as Clutch 3 on the scan tool. The transmission control module is part of the control solenoid valve assembly and is not serviced separately.
Conditions for Running the DTC
* 4th Clutch is applied.
* The clutch pressure control solenoid 3 commanded pressure is 1800 kPa (261 psi) for 3 seconds.
Conditions for Setting the DTC
The transmission control module detects the 4th clutch slip speed is greater than 100 RPM for greater than 3 seconds.
Action Taken When the DTC Sets
* P079C is a Type B DTC.
* The transmission control module inhibits gear 4.
Conditions for Clearing the 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
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 Relearningfor scan tool information.
Circuit/System Verification
1. Verify that DTCs P0721, P0722, P0723, P0966, P0967, P0969, P0970, P0971, P0973, P0974, P0976, P0977, 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 Transmission Fluid Level and Condition Check to verify correct fluid level.
3. Perform the Line Pressure Check Line Pressure Check to verify correct oil pressure.
4. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection to verify Q8 control solenoid valve assembly condition.
5. 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 Q8 control solenoid valve assembly function.
6. 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.
7. Listed in the chart below are conditions for each component that could set DTC P079C. Carefully inspect each component for that condition. Repair or replace as necessary.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Control Valve Assembly Disassemble 54. Control Valve Assembly Disassemblefor Valve Body Inspection procedures.
* Control Valve Upper Body Replacement 2ML70 - Automatic Transmissionfor Control Valve Body replacement.
* 4th Clutch Piston Removal 10. 4th Clutch Piston Removalfor 4th Clutch inspection.
* 4th Clutch Piston Installation 35. 4th Clutch Piston Installationfor 4th Clutch Assembly replacement.
* Control Module References Programming and Relearningfor Control Solenoid Valve Assembly replacement, programming and setup.
* Perform the Reset Transmission Adapts Reset Procedure following all transmission related repairs.