Lost Communication with D Door Switch
Diagnostic trouble code U0218 indicates that the main control module, typically the Body Control Module (BCM), has lost serial communication with the D door switch (usually the right rear door) over the vehicle's data bus (CAN or LIN). This failure prevents the system from monitoring the door's open/closed status, controlling power locks, windows, courtesy lights, or mirrors for that specific door.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Damaged, shorted to ground/battery, or open wiring or connectors in the CAN/LIN communication circuit to the D door switch
- Internal failure of the D door switch module (door latch module)
- Faulty Body Control Module (BCM) receiver
- Blown fuse supplying power to the D door switch module
- Software configuration error or need for BCM reprogramming
3. Symptoms You Will Notice
- D door power locks, windows, or mirrors inoperative
- Courtesy lights not working when D door is opened
- Door ajar warning light or chime malfunction for D door
4. Step-by-Step Diagnosis
Scan for related codes and check BCM data for D door switch status
Inspect wiring and connectors at D door switch and BCM for damage, corrosion, or loose pins
Test communication bus (CAN/LIN) for shorts or opens using a multimeter or oscilloscope
Check fuse supplying the D door switch module
If wiring and fuses are good, test D door switch module by substitution or using a known-good module
If all else fails, attempt BCM reprogramming or replacement
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but you may lose some convenience features for the D door. Have it diagnosed soon to prevent further issues.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether it's a wiring repair, module replacement, or BCM reprogramming.