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 P079D: Transmission Friction Element 4 Slip DetectedTypical Scan Tool Data
Parameter | Commanded ON | Commanded OFF | Slipping when Commanded ON |
|---|---|---|---|
Operating Conditions: Vehicle speed 0-80 km/h (0-50 mph) Parameter Normal Range: 0-6,000 RPM | |||
Clutch 4 Slip Speed | 0 RPM | 0-6,000 RPM | 0-6,000 RPM |
Clutch 4 Status | Applied | Released | Applied |
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 1-3 clutch is commanded Applied, indicating a slipping clutch condition.
Conditions for Running the DTC
The clutch PC solenoid 4 commanded pressure is 1800 kpa (261 psi) for 3 seconds.
Conditions for Setting the DTC
The TCM detects the 1-3 clutch slip is greater than 200 RPM for greater than 3 seconds.
Action Taken When the DTC Sets
| • | P079D is a Type B DTC. |
| • | The TCM inhibits gear 1 and gear 3. |
Conditions for Clearing the DTC
P079D 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
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Circuit/System Verification
- Verify that DTCs P0721, P0722, P0723, P0966, P0967, P0969, P0970, P0971, P0973, P0974, P0976, P0977, P2720, P2721, P2728, P2729, or P2730 are not set.
- Clear the DTC.
- Operate the vehicle from EVT 1 through 4th gear while observing the Clutch 4 Slip Speed parameter. Stop the vehicle and turn the ignition OFF for 30 seconds. Perform this action 2 times. The Clutch 4 Slip speed parameter should display 0 RPM when the Clutch 4 Status parameter displays Applied.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. |
| ⇒ | If any other transmission DTCs set, diagnose those first. |
| ⇒ | If DTC P079D resets, go to Component Testing. |
Component Testing
- Perform the Line Pressure Check.
- Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test.
- Inspect the trans fluid pump ball check valve for possible sticking or damage.
- Inspect the hybrid low, 1-2 clutch boost valve assembly, for sticking or damage.
- Inspect the 1-3 clutch assembly for a slipping or damaged condition.
| ⇒ | If a concern is found, replace the control solenoid (w/body and TCM) valve assembly. |
| ⇒ | If you found a concern with this check ball, repair the concern. |
| ⇒ | If you found a concern with the hybrid low, 1-2 clutch boost valve assembly, repair or replace the valve or valve body. |
| ⇒ | If you found a 1-3 clutch assembly concern, repair or replace the 1-3 clutch assembly as necessary. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | 1-3 Clutch Housing Overhaul for 1-3 clutch assembly repair or replacement |
| • | Control Valve Lower Body and Upper Body Replacement for lower valve body assembly repair or replacement |
| • | Perform the valve body inspection procedure, refer to Control Solenoid Valve and Transmission Control Module Assembly Inspection. If the inspection procedure indicates to replace the valve body, refer to Control Valve Lower Body and Upper Body Replacement. |
| • | Control Module References for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming |
