Subject: | Growl Groan Vibration That May Be TCC Sensitive |
Models: | 2007 Cadillac Escalade, Escalade ESV, Escalade EXT |
2007 Chevrolet Silverado, Silverado Classic, Suburban, Tahoe |
2007 GMC Sierra, Sierra Classic, Yukon, Yukon XL |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Customer concern may be a vibration, drone, or moan noise while driving. Concern may be felt in the seat or steering wheel, as well as heard. Diagnosis may show the noise may be TCC sensitive or eliminated with TCC off, typical speed range will be between 40 and 55 mph but may vary depending on gear ratio and may be more noticeable on coast. This noise/vibration will be more noticeable in a two wheel drive vehicle but can be present in an awd and 4x4 as well.
Monitor TCC slip speed in the trans data list if the slip speed range is 60 rpm of less during the concern the transmission and or torque converter if most likely NOT at fault. The concern may be ring and pinion related. To verify ring and pinion, EVA readings should be taken and may read as a prop 1 disturbance. Mark the prop shaft in 8 equal spots and using the 6 o'clock position on the differential housing as a reference, measure the ring and pinion backlash in all 8 spots. If the measurement is more than .001 difference in any of the 8 spots a concern with the pinion pitch line run out may exists. To correct the concern, replace the ring and pinion per eSI instructions.
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.