U0183: Lost Communication With Lighting Control Module - Rear

What it means

A control module is not receiving expected messages from the rear Lighting Control Module. Rear lighting functions may be affected; the code alone does not identify why communication was lost.

How it works

The rear lighting control module operates or coordinates rear lighting functions, such as tail lamps or other vehicle-specific rear lights. U0183 is set when the reporting module does not receive the expected messages from that module for the specified time. The listed possible causes include water ingress near the sunroof module, damage to the LIN wire serving that module, or incorrect CAN message routing by the gateway; verify the vehicle's wiring layout before testing.

Common causes

Most likely first.

1. Water ingress in sunroof module
2. LIN wire to sunroof damaged
3. Gateway module routing CAN messages incorrectly

Symptoms

• Rear lighting functions may be unavailable or impaired
• Other communication codes

How to diagnose it

1. Scan all modules and record freeze-frame data and related network codes to determine whether the loss is limited to rear lighting or part of a wider gateway or communication fault.
2. Check rear lamps and dashboard messages to identify which rear lighting functions are unavailable or impaired.
3. Inspect the rear lighting module connectors and nearby harness for moisture, corrosion, or damage, and check for water ingress around the sunroof module if fitted and relevant to the vehicle layout.
4. Using the wiring diagram, inspect and test the LIN wire associated with the reported fault and check the rear module's power and ground.
5. Test CAN communication and gateway routing for the rear lighting module according to manufacturer procedures.
6. If wiring, power, and network routing check out, evaluate the rear lighting module with vehicle-specific diagnostics.

Common fixes

• Dry and repair water-damaged connectors, and correct the source of water ingress if confirmed.
• Repair an open, shorted, or damaged LIN wire identified by testing.
• Restore the rear lighting module's power or ground if faulty.
• Correct confirmed CAN wiring or gateway message-routing faults.
• Replace or configure the rear lighting control module only after its circuits and network path are verified.

Can I keep driving?

Do not assume the rear lamps are working because the code is a communication fault; check the tail lamps, brake lamps, indicators, and other required rear lights before driving. If any required lamp is out or behaving unpredictably, avoid driving until it is repaired.