CAN network

U0180 — Lost Communication with Automatic Lighting Control Module

Severity: medium Drive with care, to a shop

What U0180 means

A control unit on the CAN network stopped receiving expected messages from the automatic lighting control module. This module, often combined with the light and rain sensor, shares data with the body control module and instrument cluster and turns on the headlights based on ambient light. When its messages disappear, auto mode stops working and the code is stored.

Symptoms

  • Headlights stuck off or stuck on
  • Automatic light mode not working
  • Other warning lamps may light up
  • Functions tied to the module are unavailable, such as auto lights or sometimes auto wipers
  • Other U-codes may be stored at the same time

Possible causes

  1. Failed light sensor or lighting control module
  2. CAN bus wiring fault such as an open, short or chafed harness
  3. Faulty combined rain/light sensor
  4. Another faulty module loading down the bus
  5. Corroded connectors or terminals
  6. Power supply or ground fault at the module

How to diagnose

  1. Run a full-system scan to see which modules respond and which do not
  2. Look for other communication codes that point to a wider bus problem
  3. Inspect the module's connector and harness for water, corrosion or damaged insulation
  4. Check the module's power supply and ground against the wiring diagram
  5. Measure CAN voltages and resistance at the diagnostic connector (about 60 ohms between CAN-H and CAN-L is typical)
  6. Check the fuses that feed the module
  7. Disconnect suspect modules one at a time only if the manufacturer's procedure allows it
  8. After repair, clear codes and confirm they do not return

Common fixes

  • Repair the damaged CAN wiring or connector
  • Clean corroded contacts or replace damaged terminals
  • Restore the module's power or ground connection
  • Replace the light/rain sensor or lighting control module and code it if required
  • Replace a faulty module that is pulling down the bus

Questions and answers

What does U0180 mean?

It means the network lost communication with the automatic lighting control module. The module itself may be fine, since wiring or power problems are common causes.

Can I drive with U0180?

Usually yes, but switch the headlights on manually because auto mode may not work. Get it diagnosed promptly if other faults appear.

How do I clear U0180?

Fix the cause of the lost communication first, then clear the code with a scan tool. Without a repair it will most likely return.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.