Electrical fault finding · Vauxhall Zafira B
A headlight fault traced to the UEC circuit board.
The right-hand dipped beam was not working. What looked like a simple bulb problem needed a proper electrical investigation: test the circuit, rule out the wiring and find the cause.
Check the bulb, earth and wiring under load
The bulb worked correctly and the earth connection was good. We tested the wiring under load. Supplying power directly through the original wiring confirmed that the headlight circuit could operate properly.
That evidence allowed us to move beyond the bulb and wiring, rather than replacing parts on a guess.
Trace the fault back to the UEC
With the headlight circuit tested, we traced the fault back to the Underhood Electrical Centre (UEC). Diagnostic information was considered alongside physical circuit tests; the scan alone was not the diagnosis.
Confirm the cause with a donor circuit board
Testing the system with a donor UEC circuit board brought the right-hand dipped beam back to life. This confirmed the original board as the source of the fault.
The donor board restored the dipped beam during testing. It still requires security cloning before it can be fully integrated with this vehicle. The customer has arranged that next step with a specialist.
Test. Diagnose. Find the cause. Don’t guess.
Read Matthew’s feedback on this job ↗Lights or electrical equipment not working?
Find the cause before paying for parts.
Tell us what is happening and where the car is. We will confirm the next step and whether a mobile diagnostic visit is suitable.
Current diagnostic visit: £89. Travel and first hour included in our service area, up to 60 minutes investigating one reported fault. Repairs and parts separate, only after you approve the price. See areas we cover.