Initial Inspection and Diagnostic Overview

Inspection and Verification
To guarantee an accurate diagnosis:
^ get an accurate description of the condition.
^ identify when the condition occurs; when hot or cold, during shifting, driving at a particular speed or in a particular gear.
^ have the customer demonstrate the concern, if possible.
^ see the Symptom Chart in this section for additional source information and suggested test procedures.
^ carry out the following Noise Evaluation procedures, as necessary.

Noise Evaluation

Note:
^ Carry out this evaluation with the transmission cold and at normal operating temperature to listen for any change in noise as the transmission warms up.

1. Start the engine.
2. Evaluate the noise in NEUTRAL while the vehicle is parked.
3. Listen for any change in noise while depressing and releasing the clutch pedal.
4. Listen for any change in noise while changing the engine rpm.
5. Drive the vehicle and shift through all of the gear ranges, including REVERSE. Listen for any change in noise in a particular gear.
6. Drive the vehicle in the gear in which the noise is most noticeable. Press the clutch pedal and leave the gear engaged. Listen for any change in noise.
The vibration of the engine may be amplifying the noise.
7. Drive the vehicle under the same conditions identified in the previous step. Press the clutch pedal and shift the transmission into NEUTRAL. Release the clutch pedal and allow the vehicle to coast. Evaluate the noise as the rear axle assembly turns the mainshaft.

Additional Testing for 4WD trucks:
^ Check for any noise change when shifting the transfer case between 2H, 4H, 4L or into NEUTRAL.
^ With the vehicle at a complete stop and the transfer case in NEUTRAL, shift through all the gears and evaluate the noise at different engine rpm. Check for any noises in NEUTRAL at different engine rpm.