Headlight relay / isolated wire harness install

[85crownHPP]

Sorry I dont have any pics, so I will try to be detailed. Youd just be looking at an OE looking headlight wire harness anyway... lol

Its common knowledge that fords bone head idea of running all the power for the high and low beams through the headlight switch itself can lead to frying the switch and connector - what Ive done takes the high current jiuce out of the switch and keeps it under the hood.

I wired it so that the head lights are powered right off the battery, through two maxi fuses in my underhood fuse box (fusebox thread) controlled by two relays (relay thread) in the same fuse box. The relays are activated by the stock headlight wiring, so the only current now going through the switch is whats needed to throw the relays.

As for the headlight harness, my first plan was to buy some aftermarket headlight connectors and make my own. BUT I was shocked to see that the 'Echlin' connector I bought from napa actually have SMALLER wires than the stock ones
So I did this: I pulled an entire forward lighting harness from a junkyard car, opened it up and pulled out everything except whats needed for the headlights, and wound it back up with tape. An advantage to doing it this way is that the wiring that makes the 'high' filament of the low beams come on with the high beams is built into that end of the harness.

*** note - in doing this I noticed something VERY odd about the stock wiring. ALL the forward lights on each side share one ground. This one ground is the VERY tiny little wire you find bolted to the fender well near your battery and washer tank. This wire is actually SMALLER than the ground wires coming off the headlights themselves. Thats right, the ground wire for the headlights gets smaller as it goes to the chassis, and is shared with all the other lights. You dont have to be electronics savvy to realize thats not right. WHAT THE HELL WERE THE DESIGNERS THINKING????
Maybe they got it right in some newer boxes, but this is the way it is in mine. As you may have guessed, I went ahead and snipped this little guy off and gave the harness a nice fat ground.

My headlights are definitly brighter now, and Im no longer paranoid about using my high beams for too long.

[p71towny]

Good info. I do think they fixed that ground on the newer models as my town car has a fatter ground. My vics headlights blow the towncar's lights away.

[Lincolnmania]

you are an electrical genious pete

[gadget73]

Dammit Pete, my headlight switch just blew up. You're killin me over here. You go and install a fuse box, and my fuse links start to fry, update the lighting circuit, and my switch blows up. Its like voodoo, everything you upgrade fails on my car.

[85crownHPP]

damn!!! Im sorry mang
Maybe the TC knows you want to do it, and is getting tired of waiting, hehe....

[1987cp]

:bump:

If I'm not too much out of my mind, I've seen a link somewhere for someone selling headlight connector sockets and terminals by themselves with no wire attached. I want to say a member here, maybe JumboFriendly, was involved in it somehow. Anyone remember where this was?

Alternatively, how troublesome is it to free the terminals from the lightweight wires with something like this?

[gabegt90]

http://grandmarq.net/vb/showthread.php?t=15706&highlight=relay+harness

here you go mike
It's not hard to make your own harness shit I made my own harness lol
I don;t think he sells them anymore though
are you having problems mike with your headlights?

[1987cp]

Hey, thanks. Forgot that seemed to be kind of a limited time thing.

No real problems except for needing to fix the high beams on the four-door. I did get the notion to rewire the lights on the wagon, possibly even including the four-eyed lowbeam feature, but I don't want to cut up a good original harness. Speaking of which, I wonder if anyone sells the turn signal sockets by themselves ....... I need to look through my wire pile, though... might have an extra pair of old ones from a hacked harness.

Edit: Hmmm.....



Edit edit: noticed they have two other Ford three-wire turn signal sockets. I can only assume that first one is for Grand Marquis front turn signals and these other two are for the rear, one for Grand Marquis and one for Crown Victoria.





They also list a 2-wire socket in this style ... guessing that must be for backup lamps?

[gabegt90]

what's wrong with the high beams on the 4 door?

[1987cp]

I haven't seriously inspected the harness yet, but the low beams come on only when the high beam is switched on, and the high beams are completely disconnected. It seems the guys did a four-low-beam conversion on it a while back that somehow went wrong, so I want to put the functionality back to stock for now.

I forgot to mention, on the wagon part of the motivation for digging into it is that I'm interested in getting rid of the factory headlight harness plug altogether rather than this silly arrangement of hookup wire cobbled into the harness with modified female bullet terminals and/or butt connectors.

[1987cp]

Well, as sometimes happens, I may have managed to answer my own question. It appears that the 4656 bulb uses the same style connector as the European H4/9003/HB2 style, so the connector itself should be interchangable. To support this theory, one of these links mentions 8mm terminals, which jives with me measuring my terminals at an equivalent 5/16". I'm particularly liking the look of the third link, which shows heavy-duty terminals that look identical to our OE stuff:





Oh, and the links:

http://www.comagination.com/parts.htm

http://www.eagleday.com/heco.html

http://www.rennbay.com/replacement-9003-headlight-connector-p-117.html

http://www.suvlights.com/product_info.php?products_id=124

Also turns out this Suvlights.com has a nice assortment of relays and relay plugs that could come in handy:

http://www.suvlights.com/index.php?cPath=24_49&osCsid=71b49e5aa0ad1177e14f255bcb0828b8

[gabegt90]

I haven't seriously inspected the harness yet, but the low beams come on only when the high beam is switched on, and the high beams are completely disconnected. It seems the guys did a four-low-beam conversion on it a while back that somehow went wrong, so I want to put the functionality back to stock for now.

I forgot to mention, on the wagon part of the motivation for digging into it is that I'm interested in getting rid of the factory headlight harness plug altogether rather than this silly arrangement of hookup wire cobbled into the harness with modified female bullet terminals and/or butt connectors.

it seams to me that maybe the low beams are pluged in to the to the high beam side wrong wire in the connector

[1987cp]

it seams to me that maybe the low beams are pluged in to the to the high beam side wrong wire in the connector

Right, the ground is on the opposite side. But that makes no difference if I'm just buying a connector that I'll be wiring myself.

Also came across this at Summit Racing under a brand called Pico ... sez it's for a Ford truck, but it looks suspiciously like the plug for our headlight switches. I will have to bring in an actual plug and compare.

[torquelover]

Hey Michael, the wiring craziness you see is an attempt at getting home after the headlights failed to work at 2AM on a wet 2* day (Big thanks to the mandatory on-board toolbox gods). So, as mentioned above, I redirected the high-beam output to the low-beams. If you disconnect all the add-ins, and plug everything back in it will work as normal, as long as you have replaced the faulty multifunction switch. The two NIB headlights I gave you match the low-beams currently on the car if you want to properly set up relays and wiring for the 4 low-beam-bulbs-on MIB look. There should be a brandy new relay in the mystery box I gave you just for this purpose, IIRC.

[85crownHPP]

the wiring to turn on the low beams is still connected even with the high beams unplugged, so the high filament of the low beam lamp will still burn.
Thats why the low beams light up when you hit the highs with the headlights off.