Circuit/System Verification
WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
- 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 .
- Perform the Transmission Fluid Level and Condition Check to verify correct fluid level and condition.
- 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 .
- Perform the Line Pressure Check to verify correct oil pressure.
- Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection to verify Q8 control solenoid valve assembly condition.
- Perform the Control Solenoid Valve and Transmission Control Module Assembly Solenoid Performance Test to verify Q8 control solenoid valve assembly function.
- 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.
| DTC | Component | Condition |
|---|---|---|
| P079A | Control Valve Body Upper Assembly (343) | Hybrid Low, 1-2 Clutch Regulator Valve (336) stuck - debris, sediment, binding or scored bore |
| P079A | Control Valve Body Upper Assembly (343) | Valve Retaining Plug - Hybrid Low, 1-2 Clutch Regulator Valve, leaking, undersized bore plug, or damaged |
| P079A | Control Valve Body Upper Assembly (343) | Hybrid Low, 1-2 Clutch Boost Valve (337) stuck - debris, sediment, binding or scored bore |
| P079A | Control Valve Body Upper Assembly (343) | Shift Solenoid Valve - Mode B (332) stuck - debris, sediment, binding or scored bore |
| P079D | Control Valve Channel Plate (304) | Control Valve Channel Plate damaged or contaminated with large debris |
| P079A | Control Solenoid (w/Body and TCM) Valve Assembly (307) | Clutch Pressure Control Solenoid 3:
|
| P079A | A/Trans Fluid Pump Ball Check Valve (302) | A/Trans Fluid Pump Ball Check Valve damaged, missing, or stuck |
| P079A | hybrid low, 1-2 clutch assembly | Slipping or damage |