Headlight Relay Mod for 2000 MGM with Daytime Running Lights

[IPreferDIY]

When I first read about the headlight relay mod, I thought it was something like a 3G alternator upgrade that was only necessary for older panthers. But, yesterday I learned this mod is beneficial for all panthers, and even some other vehicles.

Here are some links covering the basics:
http://www.crownvic.net/ubbthreads/u...2906458&page=1
http://www.crownvic.net/ubbthreads/u...73#Post2886073
http://www.crownvic.net/ubbthreads/u...85#Post2456285
http://www.grandmarq.net/vb/showthre...-list-diagrams

The following link has a photo at the bottom showing an example of a pre-made harness, though I wasn’t able to find out anything about compatibility or quality:
http://www.lmctruck.com/icatalog/fd/full.aspx?Page=78

Two specific issues that I want to raise are working around the daytime running lights and using diodes.

Daytime Running Lights (DRL)

My understanding is that the DRL function messes up the relays in this mod and that the DRL function has to be bypassed or disabled. In older panthers, the DRL can be bypassed with a bypass loop plug:
http://www.crownvic.net/ubbthreads/u...Number=2813864
(I’ve also seen something about getting away with just disconnecting the resistor in a pickup truck.)

On my 2000 MGM, I found out there’s a dedicated fuse for the DRL in the high power fuse box near the battery. It’s a 20A fuse, and presumably pulling this fuse cuts off the DRL power to the headlights. (My DRL module actually got fried some years ago when I had spark plug and coil issues, but I’ll assume for the purposes of this thread that there’s a good DRL module that has to be disabled.) I’m not 100% sure that pulling the fuse is the necessary fix to make the relay mod work or whether it would be better to do a wiring bypass of the DRL module since the parking brake light goes through it. Hopefully one of the experts can clarify this.

For newer panthers, the DRL function is apparently turned on and off through the computer:
http://www.crownvic.net/ubbthreads/u...Number=2713886

Diodes

I’ve read about the need to use a diode on the relay trigger circuit in some cases:
http://www.diyelectriccar.com/forums...edi-27484.html

Is this necessary for this mod? In any event, how can you tell if the relay already has a diode built into it?

I’ve also read about putting a diode between the high beam and low beam trigger wires so that the high beam trigger will activate both high beam and low beam while the low beam trigger will only activate the low beam. Any thoughts on this?

[GM_Guy]

A functional drl will turn on the relay. Or, more correctly, will turn on the relay for a period of time until the relay deteriorates.
DRL runs on reduced voltage, two things with this, with regards to the relay life, if the reduced voltage is below the reliable operating threshold of the relay, it will cause premature contact wear (ie: relay is designed to properly latch with 12 volts applied. If 10 volts is applied, the magnetic field may just barely be strong enough to latch the relay (slow latch speed) and cause arcing at the contacts. Ideally you want that latching to occur as fast as possible to reduce arcing. The other item, since drls operate at reduced voltage, you no longer have a low intensity light burning. The drl signal will turn on the relay, which will do what you installed it for: providing full voltage to the headlight.

I would be hesitant to run both high and lows in a composite headlight housing with a bulb not designed for it (excess heat).

Alex.

[monterey1962]

Some pics of the LMC 47-3662 harness kit. Connectors are plastic.

[IPreferDIY]

A functional drl will turn on the relay. Or, more correctly, will turn on the relay for a period of time until the relay deteriorates.
DRL runs on reduced voltage, two things with this, with regards to the relay life, if the reduced voltage is below the reliable operating threshold of the relay, it will cause premature contact wear (ie: relay is designed to properly latch with 12 volts applied. If 10 volts is applied, the magnetic field may just barely be strong enough to latch the relay (slow latch speed) and cause arcing at the contacts. Ideally you want that latching to occur as fast as possible to reduce arcing. The other item, since drls operate at reduced voltage, you no longer have a low intensity light burning. The drl signal will turn on the relay, which will do what you installed it for: providing full voltage to the headlight.

I would be hesitant to run both high and lows in a composite headlight housing with a bulb not designed for it (excess heat).

Alex.

That's all very helpful. I hadn't actually considered the heat issue. There's no point in substituting one problem with another.

Some pics of the LMC 47-3662 harness kit. Connectors are plastic.

Thanks Monty! Here's more info than you'd probably care to know about your relays:

http://www.shori.com.tw/upload/20130514114037.pdf

They don't have diodes in them. I don't know if they necessarily need them, but I'd be inclined to add them for the helluvit.

Can you see the wire size among the stuff printed on the wires? It should be something like "14 AWG", which is 14 gauge. (The smaller the number, the thicker the wire.) The lowest I'd want to go for the power wires is 14. The trigger wires on the relay might be as small as 18, though I'd prefer 16.

It looks like a good deal in terms of saving the hassle of doing it yourself, but I'll probably end up putting something together with 12 gauge power wires. I probably already have everything except for the relays and headlight sockets. I'm going to try to get ceramics since that should theoretically allow me to use higher wattage bulbs whenever I replace them, though I've also seen high temp plastic ones on RockAuto (Dorman #84791).

[monterey1962]

Only thing printed on them number-wise is: "AVS-2" "AVS-3.0" "0.32mm/26C".

[IPreferDIY]

Here's a link for decoding that:

http://www.seaps.com.sg/cables/cab_general_avsf.htm

And here's a screen shot in case the link disappears someday:



If I'm reading it right, the AVS-3 is 12 gauge and the AVS-2 is 14 gauge. That would be perfect for my lazy ass. Hopefully LMC has reasonable shipping to Canada.

[GM_Guy]

If you don't do U.S. purchases regularily, make sure you find out if the shipping method they use includes brokerage fees into Canada. Otherwise, you will be looking easily at an additional $30 admin fee from UPS/Fedex/DHL for doing the border clearance and paying any duties on it. This is at least one place where Rockauto shines, they factor in brokerage, and duty charges and your final payment is your final payment.

[GM_Guy]

Canadian Sources for kits;
Make sure you look at the other offers and check ships from location;
http://www.amazon.ca/s/ref=sr_nr_see...qid=1436671896

Daniel Stern, RIK-HB5 kit for two 9007 lamps: $59
http://www.danielsternlighting.com/p.../products.html

[IPreferDIY]

If you don't do U.S. purchases regularily, make sure you find out if the shipping method they use includes brokerage fees into Canada. Otherwise, you will be looking easily at an additional $30 admin fee from UPS/Fedex/DHL for doing the border clearance and paying any duties on it. This is at least one place where Rockauto shines, they factor in brokerage, and duty charges and your final payment is your final payment.

I've been stung before. In a lot of cases, the shipping itself is quite reasonable, but the brokerage b.s. kills it. What really bothers me is that we only get up to CDN$20 brokerage-free while the Americans apparently get up to US$200 brokerage-free when getting stuff from Canada. So much for "free trade". Some time ago, eBay instituted an all-included system, but not all sellers use it.

I opened an account with LMC to see what would happen, and the order page indicated they would get back to my with shipping costs before I entered my payment info. I think I'm just going to go ahead and do my own in any event. I just need a couple of relays, a couple of diodes, and a couple of headlight sockets. When you factor in the 20% exchange rate and conversion fee, I can probably get those items for less than what the cost of shipping for the harness would be.

[IPreferDIY]

I ordered some cheap relays and sockets from China (I can’t help myself), so it’ll be a few weeks before I get them. I was just going to use some scrap pieces of 12 gauge speaker wire for the power wires. The only concern seemed to be whether the insulation would be sufficient, and I would’ve covered them in a layer of electrical tape to take care of that issue. But then I saw a listing on Kijiji for 12 gauge building wire for real cheap and picked that up.

It’s RW90 with XLPE insulation. I got a bunch of red and black with seven strands, and some blue with 19 strands. It’s rated for -40C to 90C (-40F to 194F), so that should be fine in front of the radiator. Assuming there wouldn’t be any issues using this stuff, I’m figuring on posting a “for sale” ad with a GMN price of 50 cents per yard/metre. (Shipping to the states probably wouldn’t be worthwhile, but if someone from the GTA is going to Scottfest, ...) I’m figuring our cars don’t need more than six yards/metres for the power wires if the relays are mounted in the center, so that would be $3 for the power wires. If the front fender bolt on each side was used for the grounds from the headlight sockets, that would only require a foot or two more, which I would throw in at no extra cost. Any thoughts?

[IPreferDIY]

I managed to get all the necessary parts some time ago, and hopefully I'll actually be able to finish it tomorrow. Just thought I'd post a few parts pics. The first photo shows the ceramic plugs I got. (I'll do a price breakdown later.) The second photo shows the relays I got. The third photo shows the 'mating' plug that I got.



The white stuff on the plugs is regular bathroom silicone. I gave some thought to whether it was compatible with electrical stuff, and the label didn't have any warnings, so I went ahead and used it to fill the gaps and keep the wires/connectors from moving in the sockets. Only after doing that did I read about acetic acid being corrosive to metals. It shouldn't be a big concern for this, but next time I'll use a proper sealant.

The relays are one version of waterproof that I saw. You can see the epoxy or whatever at the base of the connectors. The other kind of waterproof relates to the base of the relay being sealed against its socket. I'm not going to bother with sockets for mine.

I'm using the blue plug from a pair of adapters intended for something else. I just cut one adapter and took off the extra wires that were on there. Now I have a spare for next time.