The P0644 trouble code indicates an issue with the driver display serial communication circuit. This circuit is responsible for transmitting data between the engine control module (ECM) or powertrain control module (PCM) and the driver display unit. The driver display unit provides important information to the driver, such as vehicle speed, engine RPM, and warning messages.
Driver Display Serial Communication Circuit
Code symptoms P0644.
1. Malfunction indicator lamp (MIL) or check engine light (CEL) is illuminated on the dashboard.
2. Driver display may not function properly, displaying incorrect information or failing to display any information at all.
3. Other communication-related trouble codes may be present.
4. Vehicle may experience drivability issues or decreased performance.
This code is common in brands such as:: Chevrolet, Renault, Ford, Toyota, Nissan, Mercedes Benz, Honda.
Causes of the code P0644.
1. Faulty wiring or connectors in the driver display serial communication circuit.
2. Poor connections or corrosion in the communication circuit.
3. Defective driver display unit.
4. Faulty ECM or PCM.
Code Solutions P0644.
1. Inspect the wiring harness and connectors associated with the driver display serial communication circuit for any signs of damage, corrosion, or loose connections. Repair or replace any damaged components as necessary.
2. Clear the trouble codes and perform a test drive to verify that the issue has been resolved. If the code persists, further diagnosis may be required, including testing the voltage output of the ECM or PCM and the driver display unit.
3. Ensure that the driver display unit is functioning properly. Test the unit or replace it if necessary.
4. Follow manufacturer-specific diagnostic procedures outlined in the vehicle’s service manual to accurately diagnose and repair issues related to the driver display serial communication circuit. If needed, seek assistance from a qualified technician or dealership.