P0865
PowertrainModule Communicationmoderate severityTCM Communication Circuit Low
What P0865 Means
The transmission control module communication circuit voltage is lower than the expected threshold. A short to ground or open in the circuit is often responsible.
Symptoms
- Transmission warning light
- Loss of shift control
- Limp mode
Common Causes
- Short to ground in circuit
- Open circuit or broken wire
- Faulty TCM
- Poor connector contact
Diagnostic Steps
- Scan for communication codes
- Measure circuit voltage at TCM
- Check for short to ground
- Inspect and repair wiring as needed
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