The P0863 trouble code indicates a problem with the transmission control module (TCM) communication circuit.
P0863 TCM Communication Circuit
Code symptoms P0863.
1. Check Engine Light (CEL) illuminating on the dashboard.
2. Difficulty or inability to shift gears.
3. Transmission may go into limp mode, limiting the vehicle’s speed.
4. Other transmission-related issues may be present.
Causes of the code P0863.
1. Faulty transmission control module (TCM).
2. Damaged or corroded wiring or connectors in the communication circuit.
3. Issues with the powertrain control module (PCM) or other control modules.
4. Poor electrical connections or ground faults.
5. Internal transmission problems.
Code Solutions P0863.
1. Replace the faulty TCM if necessary.
2. Repair or replace damaged or corroded wiring or connectors in the communication circuit.
3. Address any issues with the PCM or other control modules as needed.
4. Clear the trouble codes from the vehicle’s computer after repairs are complete.
5. Test drive the vehicle to confirm that the issue has been resolved.