Low Speed (15-30 MPH) Final Drive Whine Noise - 4T80E gear howl internal moan MH1 slow
| Subject: | Low Speed (15-30 mph) Final Drive Whine Noise |
| Models: | 2007-2008 Cadillac DTS |
| 2007-2008 Buick Lucerne |
| with 4T80E transaxle |
This PI was superseded to update instructions in administrative details to involve the BQM. Please discard PIP4231C.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Several TAC cases with reported final drive whine noise. Noise seems to be present in the 15-30 mph range. Noise should be evaluated at approximately 19 mph with radio off; HVAC should be on fan speed 3. Compare complaint vehicle to like vehicle. If complaint vehicle is louder than like vehicle and noise can be heard above fan speed 3 with radio off, proceed with the following repair.
Recommendation/Instructions:
Replace internal gear (120), sun gear (121) and final drive carrier (100)".
Once all three parts are installed, vehicle must be driven a minimum of 500 miles before evaluating whether the whine noise has been reduced to an acceptable level
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.
