P079A
DTC P079A
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 P079A
- Transmission Clutch 1 Slip Detected
Circuit/System Description
The transmission control module monitors the hybrid low, 1-2 clutch slip speed when the hybrid low, 1-2 clutch is applied. The hybrid low, 1-2 clutch is displayed as Clutch 1 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
* Hybrid low, 1-2 clutch is applied.
* The clutch PC solenoid 3 commanded pressure is 1800 kPa (261 psi) for 3 seconds.
Conditions for Setting the DTC
The transmission control module detects Hybrid low, 1-2 clutch slip greater than 200 RPM for 3 seconds.
Action Taken When the DTC Sets
* P079A is a Type A DTC.
* The transmission control module inhibits Reverse, Mode 1, Gear 1 and Gear 2.
Conditions for Clearing the DTC
P079A 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. An auxiliary transmission fluid pump producing low output pressure may cause a clutch slip condition. The Aux. Trans. Fluid Pump Actual parameter should be within 25 percent of the Aux. Trans. Fluid Pump Commanded parameter. 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 Control Module References for scan tool information.
Special Tools
DT-47825 - Control Solenoid Test Plate
Circuit/System Verification
1. Verify that DTCs P0721, P0722, P0723, P0756, P0757, P0796, P0797, P0966, P0967, P0969, P0970, P0971, P0973, P0974, P0976, P0977, P2720, P2721, P2728, P2729, P2730, P2797, or P0C2B 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. Verify using Freeze Frame and Failure Records, the Aux. Trans. Fluid Pump Actual parameter is within 25 percent of the Aux. Trans. Fluid Pump Commanded parameter.
• If the Aux. Trans. Fluid Pump Actual parameter is not within 25 percent of the Aux. Trans. Fluid Pump Commanded parameter, refer to Auxiliary Fluid Pump Pressure High or Low Auxiliary Fluid Pump Pressure High or Low.
4. Perform the Line Pressure Check Line Pressure Check to verify correct oil pressure.
5. 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.
6. 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.
7. Listed in the chart below are conditions for each component that could set DTC P079A. Carefully inspect each component for that condition. Repair or replace as necessary.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Control Valve Assembly Disassemble Control Valve Assembly Disassemble for Valve Body inspection procedures.
* Control Valve Upper Body Replacement Service and Repair for Control Valve Body replacement.
* Hybrid Low, 1-2 Clutch Piston Removal Hybrid Low, 1-2 Clutch Piston Removal for Hybrid Low, 1-2 Clutch Assembly inspection.
* Hybrid Low, 1-2 Clutch Piston Installation Hybrid Low, 1-2 Clutch Piston Installation for Low and Hybrid Low, 1-2 Clutch Assembly replacement.
* Control Module References Control Module References for Control Solenoid Valve Assembly replacement, programming and setup.
* Perform the Reset Transmission Adapts Reset Procedure following all transmission related repairs.