ASE G1 Auto Maintenance and Light RepairAutomatic Transmission/TransaxleMedium
A technician is inspecting a vehicle that makes a clunking noise when the driver shifts from Park to Reverse or Park to Drive. The noise is more pronounced when the vehicle is on an incline. The transmission fluid level and condition are normal, and there are no signs of external leaks. What is the most likely cause of this noise?
- AA worn internal parking pawl.
- BA misadjusted throttle position sensor (TPS).
- CAn issue with the torque converter.
- DA faulty transmission mount.
Show answer & explanationAnswer & explanation
Correct answer: D. A faulty transmission mount.
A clunking noise during engagement from Park to Drive or Reverse, especially on an incline, is a classic symptom of a faulty or worn transmission mount. The mount is designed to absorb drivetrain movement, and when it fails, the transmission can shift excessively, causing a noticeable clunk as the slack is taken up.
Why the other options are wrong
- A. A worn parking pawl would typically cause issues with the parking brake holding, or a grinding noise when trying to shift out of Park, not a clunk during engagement.
- B. A misadjusted TPS affects shift points and harshness, not a mechanical clunk during initial gear engagement.
- C. Torque converter issues usually manifest as shudder, slipping, or engine stalling, not a clunk during initial gear engagement.
Drivetrain Mounts
Drivetrain mounts (engine and transmission mounts) isolate engine/transmission vibrations from the chassis and prevent excessive movement of the powertrain during acceleration, braking, and gear changes.
- Made of rubber and metal.
- Failure causes noises, vibrations, or harshness.
- Should be inspected for cracks, tears, or separation.
Memory trick: Mount, U-joint, or Axle, makes the clunking hassle.