YTS headlamp wiring

[GreenV8S]

Anyone here worked out how the headlamp wiring is supposed to work? The V8S has been suffering from low voltage readings for the last year or so, so I thought I'd see if I can sort it out before winter closes in. I've confirmed that the battery/alternator voltage is fine, and the earths are fine, the voltage drop is scattered through the 12V side of the loom but there is a significant drop across the ignition switch. The Bible has a pretty clear wiring diagram, and some bits of it tally with the wiring on my car, but there are also significant differences (over and above the missing heated rear window, air con, headlamp motors etc). Bottom line is what I've found just seems daft, surely I'm missing something here?

The dipped headlights are fed via a relay but the relay takes its power through the ignition switch. :frown:

The main beam isn't switched by any of the relays by the ECU and I can't hear any other relays working, but surely it isn't driven straight off the light switch? But I can't see where else it could be taking power from. :frown:

The driving lights are driven by a relay but hang on, all the relay does is supply 12V to the switch when the main beam is on, so presumably the driving light switch is switching the full load? Can't fathom why they wouldn't use the switch to control the relay and drive the lights directly off the relay. :frown: The driving light relay has a permanent 12V supply (not through the ignition switch ) but I have no idea where it comes from.

The bible shows two ignition relays driving the ancilliaries, but as far as I can see the two feeds off the ignition switch go directly to the fuse box (via umpteen immobilisers etc) and feed the heater, wipers, indicators etc directly. This is the feed that is making the voltmeter read low, but the problem seems to be that there is just too much stuff being powered straight off the ignition switch and it just isn't coping. For now I've added a relay to power the headlights and other 'switched ignition' bits from the same brown/blue wire that supplies permanent power to the driving light relay, but I don't know where this supply comes from so I don't really want to leave it like that. At least it reads a couple of volts higher than it used to under load!

Unless I can find a better way, I'll probably end up adding a dedicated high current 12V feed to take the load off the existing power supplies. But has anyone got an accurate wiring diagram or followed the wiring under the dash to work out where these supplies actually come from? And is your wiring as daft as mine?

[RichardR]

I know that whenever talk of crap headlights comes up on here there's a modwise kit (IIRC) that gets mentioned, along with the VisionPlus bulbs (that I can vouch for). From my casual reading of these other postings, I think that the kit is basically a relay set which allows you to power the lights using a direct power source while the existing power is just used to trigger the new relay(s).

I could well be talking out of my arse, but if you do a forum search you'll be able to find more info.

[Ren Dao]

Sorry - have some original wiring diags - but they are there in the BIBLE - nothing different.

[Psychobert]

Have fitted 100Ws on mine (for off road use only), and will shortly be doing the modwise thing. Their kits aren't usually fitted to an S as they are slightly more troublesome than others, (I guess due to the bonnet hinging), but I'll gladly let you know how it goes..