Rear Left Door Module - Communication Error

The car's computer can't talk to the rear left door control unit properly, which might cause problems with the locks, windows, or other features controlled by that door.

The vehicle's main computer expects to receive data from the rear left door module but isn't getting the expected signals or is seeing erratic communication.

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

1. 11. Check the harness and connectors at the rear left door for damaged wires or corrosion. Repair or replace as needed. Decision: Is the wiring/connection good? If yes, proceed; if no, fix or replace the damaged area.
2. 22. With a scan tool, check if any other door modules are throwing related codes. Decision: Are there codes for other door modules? If yes, this may indicate a broader system issue; if no, proceed to next step.
3. 33. Measure voltage at the rear left door module. Expected voltage is 12V with the vehicle on and in the accessory position. Decision: Is the voltage present? If yes, the module is likely faulty; if no, check the power and ground circuits back to the main control unit.
4. 44. If the module is receiving the correct voltage, test the module by swapping with a known good module. Decision: Does the problem follow the module? If yes, replace the module; if no, further diagnosis of the communication lines is needed.

• Damaged wiring harness
• Corroded connectors
• Faulty rear left door module

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