GM Service Manual Online
For 1990-2009 cars only

A noise or vibration that is noticeable when the vehicle is in motion MAY NOT be the result of the transmission.

If noise or vibration is noticeable in PARK and NEUTRAL with the engine at idle, but is less noticeable as RPM increases, the condition may be caused by unsatisfactory engine performance.

    • Inspect the tires for the following conditions:
       - Uneven wear
       - Refer to Tire Diagnosis - Irregular or Premature Wear .
       - Imbalance
       - Mixed sizes
       - Mixed radial and bias ply
    • Inspect the suspension components for the following conditions:
       - Alignment and wear
       - Loose fasteners
       - Refer to Fastener Tightening Specifications .
    • Inspect the engine and transmission mounts for damage and loose bolts.
    • Inspect the transmission case mounting holes for the following conditions:
       - Missing bolts, nuts, and studs
       - Stripped threads
       - Cracks
    • Inspect the flywheel for the following conditions:
       - Missing or loose bolts
       - Cracks
       - Imbalance
    • Inspect the torque converter for the following conditions:
       - Missing or loose bolts or lugs
       - Missing or loose balance weights
       - Imbalance