| Subject: | High Pitch Whine or Buzz Noise Heard From Under The Vehicle |
| Models: | 2007 Cadillac Escalade, Escalade ESV, Escalade EXT, STS, SRX |
| 2006-2007 Cadillac XLR, XLR-V |
| 2006-2007 Chevrolet Corvette |
| 2007 GMC Sierra, Yukon, Yukon Denali, Yukon XL |
| Equipped With a 6L50, 6L80 or 6L90 Transmission RPO MYB, MYC or MYD |
This PI is being superseded to update models. Please discard PIP4021A.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Customers may comment on hearing a high pitched tone or whine type noise heard from the vehicle either with the key on and engine off or for up to one minute after the vehicle has been shut off. The noise should be heard from outside the vehicle only or
with a window open and be most noticeable in an enclosed area i.e. garage area.
Recommendation/Instructions:
The whine/tone is caused by the internal transmission solenoids being commanded to minimum line pressure by the TCM. This noise should be considered an operating characteristic and no repairs should be attempted.
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.
