What it means
The vehicle bus reports loss of communication with lighting driver control module A. 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 A operates its assigned lighting functions, which can include LED matrix segments and adaptive headlamp features. Other modules expect it to report over the vehicle bus; this code sets when those messages from Module A are missing.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- 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
- Scan all modules and record communication codes and freeze-frame data to see whether only Module A or several bus nodes stopped responding.
- Check whether the lighting functions assigned to Module A are inoperative or using a fallback beam pattern, and note any related warnings.
- Inspect Module A's connectors and nearby bus wiring for looseness, corrosion, water entry, or damage.
- Using the vehicle wiring information, check Module A's power and ground supplies under the conditions specified by the manufacturer.
- Test the bus wiring to Module A for opens or shorts using the manufacturer's procedure before considering module replacement.
Common fixes
- Secure or clean a loose or corroded Module A connector.
- Repair damaged bus wiring to Module A.
- Restore a missing power or ground connection to Module A.
- Replace Module A if its supplies and bus circuit are sound but it still does not communicate.
Can I keep driving?
If the affected headlamp functions are unavailable or the beam pattern is limited, avoid night driving and have the lighting fault diagnosed promptly. A fallback pattern may reduce visibility or cause glare for other drivers.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.