Lost Communication With Rear Lighting Control Module
Your vehicle's main computer lost the ability to talk to the rear lighting control module, like a walkie-talkie that stopped working. This communication break prevents proper control of tail lights, brake lights, and related rear lighting functions.
The ECU continuously attempts CAN bus communication with the rear lighting control module using a handshake protocol. It monitors for valid message responses within a specific timeout window; if no acknowledgment is received after multiple attempts, the fault is triggered.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| CAN Bus Communication Timeout | Module responds within 100-500ms | No response after 3+ consecutive attempts |
| Message Acknowledgment | Valid ACK signal received | Missing or corrupted ACK signal |
Code U0183 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, U0183 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.