Subject: | DTC P0751, P0756, P0776, P0796, P2714, P2723, Harsh TCC Engagement |
Models: | 2007-2008 Cadillac Escalade, Escalade ESV, Escalade EXT, STS-V, XLR |
2006-2008 Chevrolet Corvette |
2007-2008 GMC Sierra Denali, Yukon Denali, Yukon Denali XL |
Equipped With 6L80 (RPO MYC) Automatic Transmission |
This PI was superceded to to add note and request for digital photos. Please discard PIP4302.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Some customers may comment on a transmission concern where the MIL is illuminated and any of the above listed DTCs may be found in the TCM as active or history codes. They may also comment on harsh TCC engagement and debris may be found in the transmission oil pan.
If diagnosis leads to transmission removal inspect the torque converter face for signs of a high temperature witness mark as shown in the photo below. This witness mark will continue 360 degrees around the face of the converter and be blue / black in color.
If this torque converter high temperature ring condition as shown in the illustration is found please take a digital photo and contact TAC at the number you have been provided. Do not disassemble the transmission beyond removal of the oil pan.
Note: Engineering is only interested in torque converters that have the witness ring if there is no witness ring proceed with published diagnostics.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.