# will mk4 benefit from relaying headlights?



## L33t A2 (Aug 5, 2003)

as topic states... mk4... relays?...
my friend wants some more out of his lighting but isnt willing to pay the outrageous prices for HID or hella ecodes.
i told him all about headlight relay setups and he saw how well they improved the lighting on my mk2.
have many people installed relays for your stock (DOT) mk4 headlight housings?
did you notice any immediate benefit?
the stock bulbs are 55w H7 and i was thinking we could do relays and 65w ?? will that melt the housing?
I realize i could use a multimeter to see if there was a voltage drop at the bulb... but i am lazy and its not my car and i dont own a multimeter.
one last thing, i noticed that the mk4 uses a plug right on the back of the housing with wires then split off inside under the "boot" on the back of the housing. whats up with that? did you eliminate the headlight seal? or relayed to the (pre)plug (whats the point if it goes back down to 16ga or whatever vw skimped on for the last 5 inches)


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## Lams (Jun 17, 2003)

*Re: will mk4 benefit from relaying headlights? (L33t A2 Jetta)*

I think they already have headlight relays fitted?


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## L33t A2 (Aug 5, 2003)

not in the aftermarket sense i would use to describe a relay setup


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## mhackett (Apr 16, 2003)

*Re: (L33t A2 Jetta)*

I believe I measured around a 1-1.5 volt drop with the stock setup. A tenth or two more to the right-side lights due to longer wire required to get over there.
So relays would certainly brighten things up some, it's even possible to detect the right light being a bit dimmer than the left light if you know to look for it, at only a couple tenths voltage difference. On the other hand, it may shorten the bulb life a bit, especially if you are using extra-bright non-longlife bulbs like Osram Silverstars or Philips VPs.
There's still voltage benefit to relays even with that bit of original wire still in the housing. Resistance of that short segment is a small proportion of the total harness resistance.
I'm not using relays, I do, however, have ecodes. Relaying the DOT lights would have come in a poor second in terms of benefit, compared to the ecodes. Intensity is only part of the equation here, pattern very important as well.
Mike


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## mhackett (Apr 16, 2003)

*Re: (mhackett)*

Another issue to consider would be DRL function, if they want to use them. DRLs normally run at reduced voltage to help with bulb life; with relays that will add complication to implement.
Mike


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## L33t A2 (Aug 5, 2003)

edited: hes got the euroswitch and disabled drl
thanks



_Modified by L33t A2 Jetta at 4:30 PM 4-20-2005_


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## mhackett (Apr 16, 2003)

*Re: (L33t A2 Jetta)*

Euroswitch has nothing to do with that, I have that too, and continue to use DRLs. Many people that do get the euroswitch do also disable the DRLs as a separate step, though that can just as easily be done with the original switch.
Mike


_Modified by mhackett at 1:05 PM 4-20-2005_


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## dennisgli (May 17, 2003)

*Re: will mk4 benefit from relaying headlights? (L33t A2 Jetta)*


_Quote, originally posted by *L33t A2 Jetta* »_the stock bulbs are 55w H7 and i was thinking we could do relays and 65w ?? will that melt the housing?

I think the 65watt "H9 output" H7 bulbs would be a great upgrade for a Golf. I'm running 55/100watt H4s in my Jetta and haven't had any problems. Personally I don't think higher wattage low beams (or glaring HIDs) are a good idea. But relays and heavier wiring is a good idea - particularly if you want to run higher wattage high beams.

_Quote, originally posted by *L33t A2 Jetta* »_one last thing, i noticed that the mk4 uses a plug right on the back of the housing with wires then split off inside under the "boot" on the back of the housing. whats up with that? did you eliminate the headlight seal?

Yep, that's a problem. I ran the wires right to the bulb connector - bypassing the connector on the back of the headlight. I ran the wires through a rubber grommet out the bottom of the headlight seal so the cover still goes on. You should be able to do the same on the Golf.


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