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Home >> GMC >> 1993 >> Forward Control 7.4 N >> Repair and Diagnosis (Single Page) >> Transmission >> Automatic Trans >> Automatic Transmission - Overhaul & Testing - 4L80E >> Trouble Shooting >> Symptom Diagnosis >> No Converter Clutch Apply

No Converter Clutch Apply

Verify proper PCM or TCM operation and vehicle wiring. Damaged wiring harness or pinched wires. Brake switch not working or misadjusted. Solenoid inoperative. Oil pump valve assembly converter clutch shift valve stuck. Converter clutch apply valve stuck. Leaking solenoid "O" ring or blocked screen. Inspect torque converter for external leaks at hub weld area, or unbalanced or contaminated fluid. Turbine shaft seals damaged. Oil pump drive shaft seal damaged. Converter clutch release exhaust orifice cup plug not seated or damaged. Possible trouble Code 24, 27, 28, 37, 39, 53, 68, 75, 81 or 83.