Headlight Relay Conversion, links and parts list, diagrams?

[sxcpotatoes]

Hey, electrical gremlins with the '91 (damn grounds) means it about time to finally do the headlight relay mod. I already have enough wire, butt/crimp connectors, main power wire/fuse (4ga, total overkill), heatshrink, electrical tape, the EVTM (somewhere around here) and the relays I think Sly linked to on Amazon awhile back.

What I need help with:

-Link to the how-to thread/wiring diagram for doing the job if it's on here.

-Suggestions for a fused power distribution block (should I get one big enough for any future mods?) Like I said 4ga power wire from battery, 12 or 10 ga wiring output.

-An alternate option of way to attach the relays to the fender, or a box that's ready-made to put them in (The relays say NO:40A/14VDC & NC:30A/14VDC on them and came with pigtails & sorta brackets the relays slip onto, but I may want something better)

-Fusible links (what size do I buy/how many) & Loom (don't know what thickness/diameter I should get.

PieceItPete is graciously coming down Sunday to help me do all this, and I'd really like to have everything we need so no parts store runs need to be made.

I'd like to order as much stuff as I can from Amazon Prime sellers today (free 3 day ship) in case there's anything I can't get locally, so it's all here by Friday at the latest. Any help would be appreciated, thank you.

[kishy]

I don't have a formal write-up for you, but I did mine without having one to follow either, so as long as you've got a surplus of wire and miscellaneous stuff...also I'd recommend soldering joints and using heat shrink tubing.

I wrote this a while ago: http://www.crownvic.net/ubbthreads/u...Number=2813864
Do not disregard the bit about the DRL module, check if your car has it. I found one in a Detroit junkyard with a DRL module, there are American cars that have them even if the DRLs are not enabled.

Another bit by myself:

Yup, exactly it. You use the current +12V from the switch to turn on a relay which has a direct, fused connection to the battery.

Ideally, you'd use thicker gauge wire than stock (including new connectors for the lamps with thicker gauge wire right from the terminal, and relay sockets with thicker gauge wire - you get the idea). Anything thicker than the factory job would be an improvement; obviously the thicker you go, the less restricted the current is.

Attached what I wrote up after I did mine, so it'd be in the EVTM for future reference...not perfect and I just noticed a spelling error but should be enough to communicate the principle.

The fuse should be as close to the 12V source as possible so if your wiring melts or rubs through on something, the fuse blows.

And then there's this:
Been a while since I did that...
If I were doing it again, since I love redundancy/failover capabilities, I'd have one relay per headlamp...or at least one for low beams, one for inner high beams and one for outer high beams, but one for low and one for high will work.

[Piece-it pete]

Do 91s have DRL as an option?

I'm curious about what's been used for a distribution block/individual circuit fusing too.

Pete

[sxcpotatoes]

Do 91s have DRL as an option?

I'm curious about what's been used for a distribution block/individual circuit fusing too.

Pete

DRLs were mandatory on Canadian market cars, ours have an empty spot in fuse box where whatever unit would go iirc. My dad would know if you could order 'em in the States, but he's on a grocery run right now.

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[kishy]

90-91 have DRLs. The functionality is there whether your car is Canadian or American, it's a permanent part of the wiring harness. The components that enable/disable the feature are the 1) module, above the glovebox and 2) resistor in the driver fender.

My experience so far is that if the DRL module is installed (with or without the presence of the resistor), the relays will cook themselves in this mod, so to be safe bypass the module if you have it. The post I linked documents this.

[Piece-it pete]

Interesting, thanks.

No ideas on power distribution/fusing? On my 85 I used a brass electrical compression connector, the kind that looks like a slotted bolt with a specialty washer and nut (a home connector, not an automotive one) to connect the main power in to the 4 fusible links out, and taped it. I'm afraid it wasn't elegant. This is the style connector: http://i.ebayimg.com/00/s/MTYwMFgxMT...S8ooG/$_12.JPG

SX I have a couple of those brass connectors and some fusible links. I don't think the connector is big enough for 4 ga though. I found a fused distribution block for a car stereo, it looks really nice (but I don't think it's waterproof), 1ea 4 ga in 3 ea 8 ga out, big glass fuses, might work. I'll bring them.

Pete

[sxcpotatoes]

Interesting, thanks.

No ideas on power distribution/fusing? On my 85 I used a brass electrical compression connector, the kind that looks like a slotted bolt with a specialty washer and nut (a home connector, not an automotive one) to connect the main power in to the 4 fusible links out, and taped it. I'm afraid it wasn't elegant. This is the style connector: http://i.ebayimg.com/00/s/MTYwMFgxMT...S8ooG/$_12.JPG

SX I have a couple of those brass connectors and some fusible links. I don't think the connector is big enough for 4 ga though. I found a fused distribution block for a car stereo, it looks really nice (but I don't think it's waterproof), 1ea 4 ga in 3 ea 8 ga out, big glass fuses, might work. I'll bring them.

Pete

So I may just pick up some 8 gauge wire just in case we can use that to the relays. #overkilleverything

I'm gonna hit the local car audio shop and see if they can suggest a block etc... I'm taking the EVTM & saved that awesome wiring diagram to my phone.

Thank you dude who tipped us to bypass the DRLs. I don't want any more wiring problems in my life!

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[kishy]

Interesting, thanks.

No ideas on power distribution/fusing? On my 85 I used a brass electrical compression connector, the kind that looks like a slotted bolt with a specialty washer and nut (a home connector, not an automotive one) to connect the main power in to the 4 fusible links out, and taped it. I'm afraid it wasn't elegant. This is the style connector: http://i.ebayimg.com/00/s/MTYwMFgxMT...S8ooG/$_12.JPG

SX I have a couple of those brass connectors and some fusible links. I don't think the connector is big enough for 4 ga though. I found a fused distribution block for a car stereo, it looks really nice (but I don't think it's waterproof), 1ea 4 ga in 3 ea 8 ga out, big glass fuses, might work. I'll bring them.

Pete

Ah, right. I used inline weather resistant fuse holders for normal ATO/ATC fuses, one for the high beams, one for the low beams. My wiring comes directly off the starter relay ("solenoid"), the fuses are about 3 inches away, and then runs in a loom across the nose of the car to the driver side where I made my connections. The headlight wiring comes out from the switch along the driver side, so you can access the wires to all 4 lamps from the driver front corner of the car. My relays are just kinda hanging in sockets behind the driver side headlights, which isn't really optimal, but works. I used wire from a harness I chopped out of a junkyard car actually, it's around 10 gauge. If I were doing it again I'd probably go 8 gauge (overkill), but I used what I had available. All my connections were soldered and done up with heat shrink tubing. I regret re-using the factory headlight sockets since it means there's a tiny bit of the original wiring still carrying the current to the lamps, but they still got a lot brighter after doing it. I'll probably redo it in the future, but there's no pressing need.

So I may just pick up some 8 gauge wire just in case we can use that to the relays. #overkilleverything

I'm gonna hit the local car audio shop and see if they can suggest a block etc... I'm taking the EVTM & saved that awesome wiring diagram to my phone.

Thank you dude who tipped us to bypass the DRLs. I don't want any more wiring problems in my life!

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I'm not entirely sure you need a distribution block unless you're trying to clean up your +12V distribution for everything (e.g. 4ga wire to a distribution block and then hang all the fuse links and custom circuits off of that). I just joined my two wires to the fuses into one big ring terminal and put that on the starter relay. Note though, my starter relay has longer studs than most of the others I've seen for some reason.

[Piece-it pete]

Oh I see, we're coming from two different places. I ran my main power directly from the battery under the upper rad support to the drivers wheel well, and installed all the relays there, so I needed a way to split the power on the drivers fender.

Pete

[gadget73]

I think I'm running 12 ga wiring for all of mine. Nothing special in terms of connections, just solder and heat shrink. I don't really like crimp connectors all that much, but I have a good iron so I use what works for me.

[Piece-it pete]

Hey hot taters! You're supposed to do a (mostly) victory post!



Pete

[sxcpotatoes]

Yeah, got a little distracted by trying to catch up with two days or so of twitter that I missed.

Pete came all the way down here and helped me successfully wire in the relays on Sunday. To be truthful, he did almost all of the work, but I like to think I helped him puzzle out some of the stuff.

We tore into it as soon as I got home from work (10 hours on metal tile floors laid on concrete will make your ankles kill you, even with custom orthapedic inserts) and I stayed up past my bedtime too (after getting one hour sleep the night before work after coming back from WV family reunion).

We found the right wires, ran and zip & loomed the headlight wiring to the old factory header panel loom. I ran and fused the power wire up around the back of the engine bay while Pete did most of the relay work and wiring running. He provided a number of parts we would've been lost without like a brass wiring clamp for power distribution, and there was a wiring harness he'd pulled off a junkyard 85-86 iirc with a bunch of relays (two 16amp we used) and an awesome ring terminal attached to those that we didn't? end up using. He daisy-chained the grounds on the headlights because of a shortage of the 10?12? gauge ground wire (well, only one spool, not a shortage, but decisions had to be made to make more connections or splice in thinner ground wire.

Pete ran extra high/low beam wires for me and left them taped/clamped off for me in the high beam area in case I want to go to the awesome ALL FOUR HEADLIGHTS running high/low at once mod. in the future.

About halfway through the job my dad went out for some fried chicken and broasted potatoes (we call 'em jo-jos here) because I guess the pizza place didn't open until 3pm. Short break for refueling ourselves and we got back to it.

When it was pronounced "done" by Pete, he said, try the headlights. I told him: "reconnect the battery."

Aaaaand shit! No headlights. He said it's got to be something simple! But it was four-five in the afternoon and we were both a bit tired of it so I told him at least it's all in and almost connected right! If anything, he said, it's gotta be two wires you'll have to switch, we can make a post asking for help in the thread later. I'll get some pics up, I said. So then he left.

I went in and crashed for the night, but that's not the end of the story.



Pete looped back from the gas station because he figured it out! He had to move the switched power wire to the OTHER piece of the harness where we cut wires (I'm sure he could explain it better than I can, because I was already out like a light when this happened. My dad ran a couple tools out to him and now I have lights! The clock is on strong and keeping time, no bad ground, no flickering in or out. I haven't put the head unit back in (I pulled it when the ground shenanigans started) because I'm lazy.


I still need to figure out how to access the DRL module unplug the correct end and cut the wires I need to on the harness and loop those wires after the connector so I don't burn out my happy new relays, does anybody have a good idea of the easiest way to do that? Do I take the glovebox door off since it lives up above the glovebox somewhere?

Any further help would be appreciated, and I nominate Piece-It-Pete for GrandMarq.net Sainthood!

[Piece-it pete]

Aw shucks. After all the help I've gotten here it was the least I could do It was great working with you.

What happened was: the 2 headlight power wires in the existing harness go through a 4 prong plug. The first power I found on the plug was to the other two wires, not the headlights, running a certain way, from the male side to the female. So I assumed:


the headlight power ran the same way. Wrong! The headlight power ran from the female side to the male side. So the whole shebang was correct except I had the 'trigger power in' wires on the relays hooked up to dead wires running from the harness cut to the headlights - the wires we were replacing/abandoning.

So if I would've checked for power after cutting the harness I would've had it right from the word go. Good thing I don't claim to be a genius

I didn't know the other grounds would be affected, they must all tie in somewhere. I did tie in the existing ground into the new one, but just because I thought the parking lights might not work. I think that's called 'holy cow were we lucky'.

The old wiring harness I had was just the fusible links off the solenoids of a couple 80s' boxes I harvested at the junkyard. They came in handy!

I learned you could do this whole thing easy in two or three steps if you wanted to break it up, and still have headlights. 1) Run the main power wire 2) install relays and tie into existing harness 3) rewire the headlights at your leisure.

Blah blah blah. We'd had it so we thought instead of looking for the DLR module we'd ask you guys were it is

The chicken and jojos were very good, thanks, and your dad was good company. I'm really glad it worked out and hopefully fixed other issues, how freakin' great is that?? Hopefully we can get together sometime and not be in a rush

Pete

[Piece-it pete]

Btw, one of the jojos was the biggest jo I've ever seen!

Pete

[sxcpotatoes]

Btw, one of the jojos was the biggest jo I've ever seen!

Pete

It's not about size, it's about girth!

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