Subject: | MIL And Any Combination of DTC P0756, P0776, P0796, P2714, P2723 |
Models: | 2006-2008 Cadillac XLR-V, STS-V |
| 2007-2008 Cadillac Escalade, Escalade ESV, Escalade EXT, SRX, STS, XLR |
| 2006-2008 Chevrolet Corvette |
| 2007-2008 Chevrolet Silverado |
| 2007-2008 GMC Sierra, Yukon Denali, Yukon Denali XL |
| Equipped With 6L50, 6L80 or 6L90 (RPOs MYB, MYC, MYD) Automatic Transmission |
This PI was superceded to update Models. Please discard PIP4184.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
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.
Recommendation/Instructions:
Perform the following service procedures:
- Record Freeze Frame / Failure Data for all DTCs. This can be done electronically with the Tech 2 by capturing the data or by manually writing down the parameters. This data may be requested by TAC if further assistance is needed.
- Check and note the transmission fluid level and condition. If the level is high or low it should be corrected and the vehicle road tested to verify that the condition is still present.
- Remove the transmission bottom pan to inspect for possible debris. If debris is found the transmission should be disassembled to determine the source. Repair or replace the transmission in the most economical method following guidelines in the latest
version of bulletin 02-07-30-029.
- If no debris is noted in the oil pan remove the valve body / control solenoid and module assembly. Disassemble the valve body to:
Inspect the check balls for roundness ensuring that there are no flat spots.
Inspect the spacer plate for debris, burrs or flashing on the orifices.
Measure all the valve body bore plug (328) diameters. Specification = 11.502 mm +/- 0.004 mm.
Undersize bore plugs should be replaced.
Inspect all valves for freedom of movement and correct travel.
- Based on the specific DTC carefully inspect the following valves for freedom of movement and correct travel.
P0756 - Clutch select valve 3 (352) (closer to the manual valve) in the lower valve body (307).
P0776 - 3-5-R clutch regulator valve (336) in the upper valve body (321).
P0796 - CBR1/4-5-6 clutch regulator valve (327) in the upper valve body (321).
P2714 - 2-6 clutch regulator valve (334) in the upper valve body (321).
P2723 - 1-2-3-4 clutch regulator valve (337) in the upper valve body (321).
• | a. If a concern is found in the respective valve line-up remove the valve from the valve body. |
• | b. Once valve is removed inspect for any scratching or scoring. |
• | c. If any is found then the fingernail test will need to be performed. |
• | d. Using your fingernail to move over scratches to see if nail will try to catch on the scratch or score. |
• | e. If so then valve body will need to be replaced. |
• | f. It has been found that in most cases that the scratches are not severe enough to catch your fingernail. |
• | g. In this case the valve should be cleaned with some type of contact or brake cleaner. |
• | h. The bore should also be cleaned. Clean with machined side down so debris may escape. |
• | i. Blow off with shop air. |
• | j. To verify free movement of the valve, dip into clean ATF and install valve back into the bore, the valve should move freely. If the valve moves freely, in most cases the valve body will function properly when reinstalled. |
• | k. Reassemble and retest. |
- If no issues are noted in the valve body inspection replace the control solenoid and module assembly (314). If the concern was a DTC P2723 the input / output speed sensor assembly (303) should also be replaced.
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.