Headlight Wiring Harnesses

The headlight bulb thread reminded me my headlights suck. The plastic housings aren't terribly messed up, the bulbs are fresh Phillips Vision Plus H4s, so that kinda leaves me with voltage drop issues. Which leads me to wonder what building a heavy duty relay harness would cost me. Which led me to this, for less than I could probably build one.

http://www.amazon.com/Amico-Headlight-Female-Relay-Harness/dp/B00BQH9548/ref=cm_cr_pr_product_top

Anybody have any experience with this particular harness or one like it? Note that I never plan on going above stock wattage on account of plastic housings.

I used something similar for my wife's old Escort, worked great.

Sounds like the wire on that kit you linked to may not be of the highest quality and the assembly can be hit or miss, so you might want to go over all of the connections and wiring to make sure it is in good shape before installing.

I was going to build one for my 924s but at that price there is no way I can build one that cheap

Um, the 924S already uses a relay to drive the headlights. Fix the wiring and you won't have that problem.

EDIT: I'm partially correct, but it can still benefit from adding relays via a harness. The Rennbay harness is $134, which is insane. So here's a way to do it much more cheaply: http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/574922-upgrade-headlight-wiring-harness.html

In reply to turboswede:

The idea is you piggyback a new harness off the old, using the old solely for relay control, pulling power and ground elsewhere. Way easier than digging through the car to fix the wiring.

chances are the relays will melt down in short order, like the ones on my impala's aftermarket fan controller. once you replace them with some relays you pull from a junkyard from some 90's gm, it will work great. i've never had chinese relays last long.

I have three vehicles that need a setup like this. Please keep us updated as to how it works out.

The Jensen, on top of having the usual Lucas woes used a whopping 18 gauge wire for the headlights with no relay and these teeny little contacts in the column mount headlight switch. Someone had put Cibie H4 headlights in it with 80/90 watt bulbs, obviously in an attempt to be able to see past the front bumper, and it didn't work.

In the interest of not chopping the wiring all up, I added two 30 amp Bosch 'ice cube' relays (they are about the only Bosch product I trust) which I mounted in the front of the car. I then ran a 10 gauge wire from the battery post on the starter solenoid to a 4 place ATC fuse block, split that into two 14 gauge wires, one for high beam and one for low beam. I then wired the headlights with 14 gauge wire to the relays and used the original setup to control the relays. The headlights are BRIGHT now and it also got the 'flash to pass' working at the same time. I also had to do the same for the horn circuit, those old Lucas horns are energy hogs.

It might cost more and take longer to do it the way I did, but that's offset by reliability. BTW, the Bosch relays are now made by Tyco, good quality stuff. The cheapie relays that come in those kits are generally garbage.

Relay quality is of minimal concern, I can go to the pick and pull and get a handful from misc German cars.

I bought a harness from Daniel Stern Lighting a while ago; it was pretty expensive but at the time I had a bunch of work stuff going on and wanted a plug and play solution.

If you have any questions about lighting, he'll talk your ear off. Dude knows more about lumens than you ever wanted to know and had some really interesting advice about various offroad light setups.

Bought and installed the harness I linked, easy enough, you'd need to extend the main power lead on a car with the battery not right by one of the headlights however. Grounding is accomplished through individual ~9" leads coming off the headlight connectors. Passed the smoke test with some random junkyard relays I had laying around. Waiting for dark.

Results: Definite improvement, now it works like I expect good H4 bulbs in sorta clouded DOT housings to perform. Worth the $18 and half hour of zip tieing it took to install. Can't comment on the Chinese looking "80 AMP" relays though, they went straight into the trunk.

Update: Also replace the Chinese no name 30 amp fuses, one just melted and nuked its holder.