U0274: Lost Communication With Lighting Driver Control Module B

What it means

The vehicle bus reports loss of communication with lighting driver control module B. LED matrix segments and adaptive headlamp functions driven by this node may default to a fallback beam pattern.

How it works

Lighting Driver Control Module B controls its assigned lighting functions, which can include LED matrix segments and adaptive headlamp features. The vehicle bus is monitored for messages from Module B; this code sets when those messages are no longer received.

Common causes

Most likely first.

1. Bus wiring open or shorted
2. Module without power or ground
3. Module failed

Symptoms

• Multiple warning lights may illuminate
• Affected modules may go into limp mode or shut down
• Specific functions inoperative depending on module
• Diagnostic tools may show communication faults

How to diagnose it

1. Scan all modules and record communication codes and freeze-frame data to determine whether the fault is isolated to Module B or affects other bus nodes.
2. Check the lighting functions assigned to Module B for a fallback beam pattern, inoperative segments, or related warnings.
3. Inspect Module B's connector and nearby bus wiring for damage, corrosion, moisture, or a poor connection.
4. Check Module B's power and ground under the conditions specified by the manufacturer.
5. Test the bus circuit to Module B for opens or shorts using the manufacturer's procedure before replacing the module.

Common fixes

• Reconnect or clean a loose or corroded Module B connector.
• Repair damaged bus wiring serving Module B.
• Repair the power or ground fault at Module B.
• Replace Module B if its power, ground, and bus connections are sound but communication remains lost.

Can I keep driving?

Avoid night driving if Module B's headlamp functions are unavailable or the beam is restricted. The fallback lighting may reduce your view of the road or create glare for other drivers.