Boxster 986 - No high beams, really strange symptoms.

[Smallblock454]

Hello Paul,

as said. The wiring of USA/Canada and ROW is different. From the wiring diagram the low beam is off in the US when the high beam is on. The switches themselves are the same.

In Germany the low beam and high beam lights are both on if you turn low beam on and than high beam on. I don't know the regulations for Scotland. But i Know that in the UK there are some differences for the rear lights of the car. Think the high beam / low beam circuit is the same in the RoW.

Regards, Markus

[particlewave]

Yes, with the high beams on, both high and low beam bulbs are used.

If you haven't ordered the headlamp switch yet, don't. If a a cleaning didn't change anything, other avenues should be explored first as the headlamp switch is very expensive.

[fatmike]

faulty ignition switch results in unpredictable and random electronic faults


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[Shandy]

Studying the wiring diagram from Markus suggests it's going to be the turn signal /dimmer switch that's causing this. I have an ignition switch ordered but that looks to supply power to the headlamp switch only. As the low beams and fog lights all work OK it's really pointing towards an issue with the power supply from the turn signal /dimmer switch terminal 56a to fuses A1 and A2. It looks like the high beam flash control (pulling back on the stalk) has it's own power supply (bypassing the headlamp switch entirely) so this should work independently of any power supply issues from the headlamp switch side. I should get a chance to investigate further towards the end of this week, I'll let you know how I get on!

Thanks for the help and suggestions so far.

[Shandy]

Fixed! I finally got a chance to try replacing the stalks and full beams are now working again. Studying the wiring diagram really helped to work out which part was causing the problem. Thanks all for the advice.