Transmission Slip, Shudder or Grind Noise in First, Second or Reverse, DTC P079A Set (Replace Transmission Rear Case Assembly)
| Subject: | Transmission Slip, Shudder or Grind Noise in First, Second or Reverse, DTC P079A Set (Replace Transmission Rear Case Assembly) |
| Models: | 2008 Chevrolet Tahoe Two-Mode Hybrid |
| 2008 GMC Yukon Two-Mode Hybrid |
| with 2ML70 Automatic Transmission (RPO M99) |
| and Built Prior to VIN Breakpoint 8R204089 |
Condition
Some customers may comment on any of the following conditions:
| • | Transmission slips, shudders or grinds on launch. |
| • | Transmission slips in first, second or reverse gears. |
| • | Check engine light illuminated. |
These conditions will typically be noticed after the transmission reaches full operating temperature. A scan tool may reveal DTC P079A. The DTC will only set under hard acceleration.
Cause
This condition may be due to the hybrid low, 1-2 clutch snap ring becoming mis-located, causing the piston to over-travel and the clutch to slip. This condition may also be caused by delamination of the hybrid low, 1-2 clutch piston.
Correction
Replace the automatic transmission rear case assembly. Refer to the Rear Case and Gasket Replacement procedure in SI.
The rear case was formerly available only as part of the entire transmission assembly. DO NOT replace the transmission assembly for this condition.
Parts Information
Part Number | Description | Qty |
|---|---|---|
29544364 (2WD) | Case, A/Trans Rear | 1 |
29544376 (4WD) | Case, A/Trans Rear | 1 |
29544388 | Gasket, A/Trans Rear Case | 1 |
29544371 (2WD Only) | Gasket, Output Housing Extension | 1 |
24242395 (4WD Only) | Gasket, Transfer Case Adapter | 1 |
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation | Description | Labor Time |
|---|---|---|
K6388 (2WD) | Rear Case Replacement | 1.5 hrs* |
K6388 (4WD) | Rear Case Replacement | 2.2 hrs* |
* This time is updated from the current Labor Time Guide. The next update of the Labor Time Guide will contain this change. | ||
