issues with 2009 vw golf hid

Here is a very rough MS Paint diagram of what / how I am testing. Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

You can't measure the voltage without the bulbs installed. Reinsert the bulbs, switch to DRLs and then measure across each bulb. Or use equal wattage smaller bulbs or maybe resistors - eg, two 1/4W (or higher) 1k (or higher) resistors.

Ahhh... I was not aware of that. I may have been around the 12v world for a while, but there is still plenty I don't know... I'll be a noob for a while... lol. When he gets back and we get our hands on the car I'll give it another go. But I have a feeling you are right and my issue is with too low of a voltage. If that is the case, is there a way to use both bulbs and get my 12v (ie running in series)??? If so, is it just a simple relay to + of one side, - of that side to + of the other side, then - of the other side back to the relay? Or is it not just a simple series circuit??? Thanks again for all the help!Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

Well that's the issue - how do you intend to power the HIDs in DRL mode? You can't series connect them...

Figures... I didn't think it would be that easy... lol. Since the DRL's come on with ignition anyways and as far as I know the ONLY time they are off while the car is on is POSSIBLY when the high beams are on. So I may end up running a wire from under the dash (tagging the same parking light wire as I would for a r/s) to the relay under the hood... or I may try testing the parking light wires and using the side marker light to trigger the relay. I'm not 100% sure yet, nor am I even sure we will have to worry about it. He said that it only had the problem once. So when he gets back I'll see if he even wants to bother with it or not. Thanks for the help!!!Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

Were the DRLs the original bulbs (and hence probably in series), or are the DRLs separate lights? Although HIDs could operate from half voltage, they'd still be at full brightness. Their ballast is (as far as I know) a dc-dc converter, and not that I expect most to be capable of running with a 6-7V supply, automotive dc-dc converters are capable, viz PC ATX-type DC PSUs, and my recently posted link to current-logic.com. But hence the DRL mode must be inhibited from appearing at the bulb sockets (so the relays get their full 12V coil voltage) and some other lighting used as DRLs (maybe bright parkers?). But perhaps some HIDs have a dim(mer) mode? And if series switching is used, then the 12V relays should operate from ONE of the 2 bulb sockets provided the coil GND is not grounded thru the bulb socket. IE - one bulb's +12V should remain in DRL mode. The other bulb's +12V is reconnected to GND, and both bulb grounds are (still?) connected together but disconnected from GND so that they "float" at ~6V (half the supply voltage). That's one way of switching non-polarised bulbs from parallel to series. But even for polarised lights (eg, LEDs, HIDs - even though they would not use series connectivity for DRL mode), one bulb should still have one pin at +12V irrespective of iy being in beam or DRL mode. And that's what you could use to energise the relay(s) for the HIDs, though you shouldn't need the relay... Another method could be to use 6V relay(s) but with a current limiter for each relay coil - else a 6-7V voltage regulator. (The LM317 being ideal for either case.) PS - it should be solvable and doable, the issue is finding the appropriate method. And it also assumes no CAN nor current sensor etc complications. I don't know how far they have integrated such interfaces, but if changing radios can disable a vehicle, I dread to think what a "safety" requirement like lights could do (though not disable the vehicle, I hope... but then again...)

I'll see what happens when he gets back. I will test the headlight wires again but with the factory bulb connected and see what I get. if its not 12v then I'll test the parking light and see if I get 12v there. If so I'll just connect the relay to the parking light trigger. We'll see what happens.Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205