Typical Faults:

1. One-Way Clutch Roller Jamming

   • Symptom: Harsh 1-2 upshift or delayed reverse engagement (P0730/P0756 codes)

   • Cause: Contaminated fluid or sprag spring fatigue

2. Drum Spline Wear

   • Symptom: Reverse slippage or metallic noise

   • Trigger: Hard shifts causing torsional stress

3. Thrust Washer Failure

   • Symptom: Axial play >0.25mm (whining in reverse)

   • Root Cause: Improper assembly torque

Critical Checks:

• Sprag Clutch Test: Should lock counterclockwise only

• Drum Runout: <0.08mm tolerance

• Fluid: MERCON V only – others degrade OWC lubrication

Pro Tip: Replace entire drum assembly if splines show polishing – indicates mutual wear with planetary gears.