Code 81 - Shift Solenoid "B" Circuit: Notes

Fig 1: Code 81 Circuit Diagram

Courtesy of GENERAL MOTORS CORP.

The quad driver (inside PCM/TCM) has a fault detect circuit, which is monitored by PCM/TCM. PCM/TCM compares voltage values of fault detect circuit with acceptable values in PCM/TCM memory. If PCM/TCM senses voltage is not within acceptable range, Code 81 will be set.

1. This step checks shift solenoid "B" and circuits inside transmission for shorts.
2. Battery voltage should be present at shift solenoid "B".
3. This step checks circuit 1223 for short to ground.
4. This step checks if PCM/TCM can control solenoid "B".
5. This determines whether circuit 1223 is open or PCM/TCM is faulty.