I'm currently diagnosing a lighting issue with an L322 2002 vogue where the D/S dipped beam xenon does not ignite, if the light switch is turned on and off a number of times the dipped xenon will ignite, a new ballast / ecu, ignitor, and light internal wiring loom has been fitted, what function does the LCU perform, does it supply 12v to the ballast / ecu on Yellow Blue wire or act as a sink (12v Neg applied to the headlamp ballast / ECU), As a replacement ballast / ecu has been fitted will it require coding to the vehicle with Testbook ??

Any help appreciated

Fit a second hand headlamp? From £50 on the bay

I'm awaiting delivery of just such a unit, I'll strip it, clean and fit new bulbs before fitting, I was still looking for info on the LCU outputs, thanks for the response

The plugs are the same on both headlamps so you could check the good one on the bad side and if it works, change one componant at a time from L to R and you should eventually find your issue...

Have done, ? hence the question, when the lights are on there is no perceptible voltage on either YU (yellow, blue for R/H dipped beam) or WG (white greeen for l/h dipped beam ) ? tested both to earth and to pos 12v.

Hmmm most peculiar issue... Usually it's an issue with the igniters hence you turn them on & off a couple of times and they work...

Yes,
Ive replaced the ignitor (and the internal harness in the light) as there was signs of water contamintaion on the ballast pins and the harness connector but still the same issue. I have substituted a known good LCU with both the same result and readings ? not getting anywhere fast, I'll wait and try a full headlight substitution,

Hi, If you are anywhere near Washington on Monday I have a known good headlight out of my car, There is no front end on at present so plugs are readily available bring the suspect light and try in my car ?

I had the same issue with my passenger side head light , changed the ecu,igniter and lamp then it stopped for a while ,then started again , the negative is bolted with about 6 others to the inner wing ,removed that and cleaned the post and tightened it back up and it was ok for months but now its started again takes 6 or 7 times to light some times and other times lights straight away ,tested at the light and it gets about 12.7v ,the negative is about 0.5 ohms to the battery so just living with it now.

Thanks mick-ne I'll try my replacement first and see what develops, thanks for the offer again, if I need to take you up on it is there a time limit (when will you be re assembling your vehicle).

No time limit at present so just see how you get on. The car is at work five minutes from Washington services on a1, so any weekday is fine,just shout.