Morning all!

Odd one for you: when using the headlights, both dipped beam work without issue. When flashing or switching to main beam and back, one dipped beam stops working entirely. (Always the same: passenger side)

This stays off until the trucks been parked for a while, then works again.

Ive read contradictory information where some posts say there is a relay for this which might be sticking, others say this is directly controlled by the BCU and some say it is all in the stalk switch so that needs checking/replacing. Which is correct?!

I note that RAVE shows a pinout on the BCU for headlight dipped and headlight main separately, but does that feed a relay? Surely the BCU isn't supplying and switching that power all on its lonesome?

Cheers,

Hi, the reality is revealed by the circuit diagrams and based on that the headlamps(high and dipped) get feed directly from the stalk through the fuses in the interior fusebox, no relay or other electronics involved, the BCU has to do only with the IP's high beam indication(or DRL which is not UK specific) so your problem is a weak contact which can be in the stak, in the cluster's plug (which is common), that lamp's earth or in the worst case interior fusebox plug or within it, investigation is needed

sierrafery said:

Hi, the reality is revealed by the circuit diagrams and based on that the headlamps(high and dipped) get feed directly from the stalk through the fuses in the interior fusebox, no relay or other electronics involved, the BCU has to do only with the IP's high beam indication(or DRL which is not UK specific) so your problem is a weak contact which can be in the stak, in the cluster's plug (which is common), that lamp's earth or in the worst case interior fusebox plug or within it, investigation is needed

Click to expand...

Thanks Sierra. Ill start by checking the earth on the lamp end, though its odd that it works fine until high beam is switched, suggests the issue is more likely at the stalk end which is mildly upsetting!