hey, i have an 08 Scion xD which has a common positive headlight system (H4's) i already have an after market Low only HID kit in there. im adding fog lights which will be controled by the high beam switch. The problem is that when the Highbeam is engaged the low is turned off.
How can i wire a relay so that when i toggle the high beams the lows will stay on.
The factory wiring is such that:
Wire A - Always Positive
Wire B - Low beam Pos/High Beam Neg
Wire C- High beam Pos/Low beam Neg
Thanks!
Fog lights with high beams? That is contradictory (and illegal in many localities). (Having said that, my rally driving fog technique was full beam-spots until you saw an obstacle, then decide whether to go left or right...)
And are you sure the H4s are common +ve as opposed to the relay?
Normally diodes are used for what you describe. EG - my former outer H4s are now dedicated low (H1) whose relays are now triggered by "beam" power (before the dip switch) and also a diode from the hi-beam for the "flash" function. (I didn't need an inline diode in the beam to low-beam to prevent back feed.)
my fog lights will be controlled by the high beam switch on my car. my car has no high beams.
Hmmm - it might still be "technically" illegal because you have lows on with fogs....
That used to be illegal here, but AFAIAC, so many new cars have "fogs" which are on with low beams etc. ("Fog" by my definition meaning "low spread", not yellow etc.)
But in that case, it is as I said above - a diode.
That tends to assume relays - you either have a change-over switch controlling 2 relays, or a master switch or relay into a changeover relay.
(FYI - I prefer the former; the latter is less reliable.)
Two diodes and a relay you could do this at the oem h4 socket in the engine bay at the side closer to the battery post, and the fogs can be used of the original high beam supply at the socket for the fogs.