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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission - Diagnosis - 4L80-E >> Component Test Charts (No Codes) >> Force Motor Circuit >> Notes

Force Motor Circuit: Notes

Fig 1: Force Motor Circuit Diagram
G92I14140Courtesy of GENERAL MOTORS CORP.

PCM/TCM monitors signal return amperage. If return amperage varies more than .16 amp from amperage sent by PCM/TCM, Code 73 will be set. If this occurs, force motor is disabled and maximum line pressure occurs.

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. This step checks control of force motor by PCM/TCM.
  2. Voltage should be present.
  3. This step checks if problem is inside transmission.
  4. This step checks for short to ground.
  5. This step checks for high resistance inside transmission.