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 cause may be from poor engine performance.

    • Inspect the tire for the following:
       - Uneven wear
       - Imbalance
       - Mixed sizes
       - Mixed radial and bias ply
       - Refer to Tires and Wheels.
    • Inspect the suspension components for the following:
       - Alignment and wear
       - Loose fasteners
       - Refer to Front Suspension.
    • Inspect the engine and transmission mounts for damage and loose bolts.
    • Inspect the transmission case mounting holes for the following:
       - Missing bolts, nuts, and studs
       - Stripped threads
       - Cracks
    • Inspect the flywheel for the following:
       - Missing or loose bolts
       - Cracks
       - Imbalance
    • Inspect the torque converter for the following:
       - Missing or loose bolts or lugs
       - Missing or loose balance weights
       - Imbalance