Diagnostic Instructions
DTC Descriptor
DTC P079A: Transmission Friction Element 1 Slip Detected
Typical Scan Tool Data
Hybrid Low, 1-2 Clutch Reference
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 1 Slip Speed
| 0 RPM
| 0-6,000 RPM
| 0-6,000 RPM
|
Clutch 1 Status
| Applied
| Released
| Applied
|
Circuit/System Description
The transmission control module (TCM) monitors the Clutch 1 Slip Speed for each Hybrid Trans. Mode Commanded state. This DTC detects clutch slip when the hybrid low, 1-2 clutch is applied.
Conditions for Running the DTC
| • | The clutch PC solenoid 3 commanded pressure is 1800 kpa (261 psi) for 3 seconds. |
Conditions for Setting the DTC
The TCM detects Hybrid low, 1-2 clutch slip greater than 200 RPM for 3 seconds.
Action Taken When the DTC Sets
| • | The TCM inhibits Reverse, EVT Low, 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. 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
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 1st through 4th gear while observing the Clutch 1 Slip Speed parameter. Stop the vehicle and turn the ignition OFF for 30 seconds. Perform this action 2 times. The Clutch 1 Slip Speed parameter should
display 0 RPM when the Clutch 1 Status parameter displays Applied.
| ⇒ | If any other transmission DTCs are set, diagnose those first. |
| ⇒ | If the DTC P079A 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.
| ⇒ | If a concern is found, replace the control solenoid (w/body and TCM) valve assembly. |
- Inspect the trans fluid pump ball check valve for possible sticking or damage.
| ⇒ | If you found a concern with this check ball, repair the concern. |
- Inspect the hybrid low, 1-2 clutch regulator valve for sticking or damage.
| ⇒ | If you found a concern with the hybrid low, 1-2 clutch regulator valve, repair or replace the valve or valve body. |
- Inspect the hybrid low, 1-2 clutch assembly for wear or damage.
| ⇒ | If you found a hybrid low, 1-2 clutch assembly concern, repair or replace the low and reverse clutch assembly as necessary. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
