Different functions within a headlamp may use different circuits or electronics. A working dipped beam does not prove that the daytime running light’s supply, driver or light source is healthy.
Define the affected mode
Record whether the fault occurs on one side, whether the dashboard reports it and whether normal lighting settings change the result. Include headlamp replacement, water entry or front-end repair history.
Avoid assuming every headlamp has a separately repairable daytime-light module. The workshop should identify the assembly and supported service options before parts are ordered. Do not open sealed lamps or bypass the monitoring circuit. Send external label details and the exact failed function so the assessment can distinguish local lamp work from a vehicle-side control problem.
Need help with this fault?
- Headlamp Levelling Warning After a Suspension Spring Change
- Automatic High Beam Stays Unavailable in Clear Conditions
Browse this collection or prepare a vehicle and module enquiry. Tell us about the vehicle, the fault and any tests already done. Contact our Didcot workshop before travelling or posting a module. Visits are by appointment.