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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 Clutch 3 Slip Detected

Typical Scan Tool Data

1-3 Reverse Clutch Reference

Parameter

Commanded ON

Commanded OFF

Slipping when Commanded ON

Operating Conditions: Vehicle speed 0-161 km/h (0-100 mph)

Parameter Normal Range: 0-6,000 RPM

Clutch 3 Slip Speed

0 RPM

0-6,300 RPM

0-6,300 RPM

Clutch 3 Status

Applied

Released

Applied

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 N·m (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 over-speed 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

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References 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.
    2. ⇒ If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Perform the Transmission Fluid Level and Condition Check to verify correct fluid level and condition.
  3. Perform the 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 to verify control solenoid valve assembly condition.
  2. Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test to verify control solenoid valve assembly function.
    3. ⇒If a malfunction is found, replace the Q8 control solenoid valve assembly.
  3. Inspect the a/trans fluid level control valve for stuck closed or damaged condition.
    4. ⇒If you found cause for concern in 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:
    5. • 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 cause for 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.
    6. ⇒If you found the 1-3 reverse clutch assembly to be damaged, repair or replace the 1-3 reverse clutch assembly as necessary.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    • Control Valve Body Replacement for control valve body replacement.
    •  1-3-Reverse Clutch, Input Clutch Hub, and Hub Shaft Removal
    • Transmission Replacement for Transmission removal
    •  Control Module References for Control Solenoid Valve Assembly and Transmission Control Module Assembly replacement, programming, and setup.
   


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