USDM foglight harness mod, part II - Honda Prelude Forum

alphajesse · 03-24-2003, 02:45 PM

Ok, so you've done the modification in this thread courtesey of JakeTheSlayer,
and you're happy, cause your fogs work with both the parking lights and regular headlights. But you still yearn for more- you want those fogs to work in concert with the highbeams. You totally disconnect the 2nd relay (the gold one) but all that does is make the fogs not work at all, even though every other part of your lighting system acts normally.
So what do you do?

The gold relay is a 5-post relay, but only 4 of the posts are used. It's a normally closed relay, meaning the circuit is complete as long as the other end of the relay does not receive power.

Looking at the plug that goes into it, there is a white wire, and another white wire with an orange stripe. this is the ground for the 12v foglight power. I don't have any pretty pictures, but this should be fairly easy to figure out.
cut both of the white wires (striped and non-striped) and strip off the insulation on the harness side of things. Simply connect the ends of these two wires. You are done.
To make it pretty, I used quick disconnects on both wires, and a short 'jumper' wire to connect everything. I also put quick disconnects and taped the ends of both the wires left in the plug. This kept them safe from shorting anything out, and left the mod easy to undo if I decided that the power of foglights combined with highbeams was too much for public roads.
From there you can plug the relay back in, or leave it undone. In my driving around, it didn't seem to make any difference, but I left it plugged in, just in case the other wires were important grounds.

After doing this (and assuming you did harness mod #1), you will notice that the fogs only turn on when the parking lights or headlights are on, but flashing the highbeams, or just turning them on will not turn them off. If you just flash your highbeams without at least the parking lights on, you will notice that the fogs will not work.

Thanks to Jacob for starting this harness modding madness.

vipastyle · 03-24-2003, 05:03 PM

FAQ.

ThatPreludeGuy · 03-24-2003, 05:29 PM

Something I dont get is why go buy the US harness? Isn't it like $70-80, the method I used cost me about $10 for a relay, wire, and some butt end connectors.

Oh yeah it lets the JDM's come on with any light and stay on, ie parking, low beam, or high beam.

vipastyle · 03-24-2003, 05:40 PM

^^ hmm...

ShadowSonic · 03-24-2003, 05:42 PM

Quote:

Originally posted by THATPRELUDEGUY
Something I dont get is why go buy the US harness? Isn't it like $70-80, the method I used cost me about $10 for a relay, wire, and some butt end connectors.

Not everyone is able to think like you

some like the adventure of doing something different.

ThatPreludeGuy · 03-24-2003, 05:46 PM

Quote:

Originally posted by 99Interlude

Not everyone is able to think like you some like the adventure of doing something different.

I guess it just seems like a waste of time and money to me. For the extra $70 you can get some real performance like a Spoon oil cap!

alphajesse · 03-24-2003, 06:18 PM

i got the harness and button from wreckdriver for $20 shipped, so this was pretty cheap. also- the harness has the connector for the factory switch built in. finally, the harness is about $40 from hondaautomotiveparts.com so no big deal there.
my fog switch also doesn't operate foglights

axion68 · 03-24-2003, 06:36 PM

Quote:

Originally posted by THATPRELUDEGUY
Something I dont get is why go buy the US harness? Isn't it like $70-80, the method I used cost me about $10 for a relay, wire, and some butt end connectors.

Oh yeah it lets the JDM's come on with any light and stay on, ie parking, low beam, or high beam.

I bought it because I am anal about stuff like that. I wanted something that was plug and play, and clean. I could have bought a cheap pair of fogs from walmart, but I wanted something proven and that plugs into the existing wires without splicing.

ThatPreludeGuy · 03-24-2003, 08:53 PM

Quote:

Originally posted by JakeTheSlayer

I bought it because I am anal about stuff like that. I wanted something that was plug and play, and clean. I could have bought a cheap pair of fogs from walmart, but I wanted something proven and that plugs into the existing wires without splicing.

I see that to some degree but the JDM harness only needs a very minor mod to fit into the USDM switch and then yeah you do need to cut and splice the harness but you guys are doing that to the USDM anyway.

5Gen_Prelude · 03-25-2003, 12:36 AM

If you are using the JDM harness, you don't need to splice anything.

ThatPreludeGuy · 03-25-2003, 06:41 AM

Quote:

Originally posted by 5Gen_Prelude
If you are using the JDM harness, you don't need to splice anything.

Well that depends on what you want, if you want to use the JDM harness with the USDM switch and have your fogs go on like I described I don't know of any way to do this without splicing.

Now that would be an interesting project if some pins could be switched around to give that ability.