Headlight relay mod revisited...my way to do it and save some money
 

I was wandering around looking under the hood of junk cars, scavenging hose clamps and other usefull trinkets when I spotted the perfect thing.

On a FWD Mopar puke car, late 80's, early 90's there is a perfect little bracket with two Bosch style relays on the fenderwell.

These are the exact relays you need to do the headlight relay mod and not have to order them or buy them new. A Bosch relay is a Bosch relay. These were priced perfectly, free.

Here's some pics of what I'm talking about...

If you do this mod, please do it right, so it's reliable.

I posted a picture of good quality crimping tools. Those 4 dollar do-it-all electrical tools suck. Spend 25 bucks and enjoy the good life.

I also posted a picture of a neat tool I use. It's a miniature butane torch. I originally saw the Boyd's guys using them on TV. My wife picked one up for me at Home Depot. It's a godsend for heat shrink tubing in tight areas.

Finally, there is a picture of a finished connection. Notice there are no connectors with colored plastic sleeves. Remove the sleeve and expose the bare connector. Then crimp with a good tool. Next, solder the connection to the terminal. Finally, cover with heatshrink.

Matt covered the basics of this mod in his post, I'm just elaborating on a good way to do it even cheaper.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Nice write up!. How did you know which terminals to hook up the headlight wires???. They look slick.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Go here, and look at page 5. I just printed the page off for my tech notebook that I keep on my workbench.

http://sonolithics.com/files/bosch.pdf

Warning, not for the dial up guys, that's a big PDF file.

Re: Headlight relay mod revisited...my way to do it and save some money
 

The sonolithics lists the terminal numbers on the relays, and if you look closely at the bottom of the relay themselves, the same numbers are on them.

Also, I swapped the driver's side headlight plug for a spare passenger side plug I had laying around. Once you cut the original wiring apart, you will be left with two extra unused wires on the left headlight plug. The right headlight plug is exactly the same, but doesn't have the two unused wires hanging off of it. I did this strictly for a neater appearance. I didn't want two little short stubs of cut off wires sticking out and looking shoddy.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Great stuff. Might want to include a link back to the original wiring explanation thread just for the purpose of archival. Curious - what car exactly did it come out of? (rough estimate?)
i went to the junkyard today and just wanted to let everyone know - you can find the relay setup that Tex is talking about on 92-94 Dodge/Plymouth's : Sundance/Duster/Shadow models and I think also on the Summit as well. The relay setup is bolted to the driver's side shock/strut tower with what looked like a 1/2" or 13mm bolt. I seriously found at least 10 of them in good shape - and I didn't even make it all the way through the Mopar section of my local Pull-A-Part, so they are definitely out there to be had."

Re: Headlight relay mod revisited...my way to do it and save some money
 

Late 80's or early 90's FWD Mopar with 2.2 or 2.5 engine. I think it was a Sundance or similar.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Here's how I set up my son's Blazer (orangeuavol).

Re: Headlight relay mod revisited...my way to do it and save some money
 

Home Depot has started carrying more "REAL" electrical tools. I know they have those there.

Personally I use a GreenLee ratcheting cyclical crimper. I have the dies for insulated and uninsulated terminals. Works like a champ and you don't get a hand cramp from using them.

Also, I have noticed that LMC is now selling a supposedly "plug-in" upgraded headlight relay harness. I believe it was $29.99

Re: Headlight relay mod revisited...my way to do it and save some money
 

Mine are Klein brand. They cost 22 dollars a few years back. Worth every cent too.

You can get them online for 20 bucks.

http://www.mytoolstore.com/klein/1005.html

Re: Headlight relay mod revisited...my way to do it and save some money
 

I have a hard time understanding how this works. Page 5 is what I should be looking at for the directions ? Any specfic info on how to do this to our trucks ?

Re: Headlight relay mod revisited...my way to do it and save some money
 

Oh, and here is how I did mine up:

http://www.zieglerdigital.ca/public/...tricfans01.jpg

I haven't run the power wire from the firewall distribution block to the core support dist block yet, but other than that, its all ready to go.

Still plan to buy an H4 European style bosch headlight conversion kit for the truck yet, both sealed beams have one of their beams burnt out.

I have an H4 kit in my 77, without the relays, and dang is it ever nice! Can't wait to see it done up with the relays!

Re: Headlight relay mod revisited...my way to do it and save some money
 

Got mine at NAPA. Got the ticket somewhere--will look up the number for you.

Re: Headlight relay mod revisited...my way to do it and save some money
 

TxFirefighter, did these have any female plastic connector housings attached to the relays from the MOPAR donor car or did they attach like you show in the photo?

Re: Headlight relay mod revisited...my way to do it and save some money
 

72Mario. Basically, here's the deal. Power must travel from your battery all the way to the light switch then back to the lights. This induces a lot of resistance and voltage drop. The end result is that far less than battery voltage reaches the lights, causing them to not be as bright as they could be.

The relay mod changes all this. It makes it to where the power only has to go from the battery through the relay on the core support and then to the headlights. This is a much shorter pathway with fewer sources of resistance. The end result is full battery power reaches the headlight and that gives 30 to 50 percent improvement in headlight output.

Mad electrical has a great article on their website which explains this fully, in easy to understand language.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Here is the link to MAD's article. There are two pages with lots of pictures.

http://www.madelectrical.com/electri...adlights.shtml

Roger, the Mopar used a nice plug with the wires securely positioned. Only thing was, the owner had stripped this car of it's entire wiring harness. So, I was able to get the relays, but not the connectors. I'm sure you'd be able to get them off your donor though.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Mario, maybe this will help (I hope)

http://www.73-87.com/7387garage/exte...ight_relay.htm

Re: Headlight relay mod revisited...my way to do it and save some money
 

It's a phenolic deal with a metal stud made into it.

A wire comes from the positive battery terminal to this block. From there, two wires travel across the core support and into the trucks wiring harness.

If you're having troubles in this area, check your fusible links. Use a testlight and also try to stretch them. Sometimes, a fusible link fails, but still looks fine. They go bad inside the insulation.

Re: Headlight relay mod revisited...my way to do it and save some money
 

To Tex.: here is the item # for circuit breaker at NAPA--BK 7823105

Re: Headlight relay mod revisited...my way to do it and save some money
 

By the way DO NOT use a fuse in your headlight circuit between the power source and your relays. Why? Pitch black road--75MPH-- hit a bump or whatever--light wire shorts and blows fuse--no lights and a curve coming up that you cannot see--ouch. Circuit breaker--lights goes out-comes back on -goes out and so forth. The circuit breaker in the light switch will protect the wires from light switch to the relays.

Re: Headlight relay mod revisited...my way to do it and save some money
 

Alright guys here is another source for a relay panel. I got mine from work actually, I work for Ford and had some wire looms laying around the entire things. Had some small relay boxes i had set aside for later projects and i ended up using one of them for my elec cooling fans (which also got from work they came off a wrecked Escape) They are in a plastic case with a removable top and you can replace the the relay if need be very easily. These can be found in most late model Ford vehicles like '97-03 F-150's. Inside the truck on the pass side under the panel on top of the dash is probably the easist to get to. I will take pic of it tomorrow and post them and pics of the cooling fans also they work great. I can have it sitting still running and turn the fans on and cools it so well the guage registers just below the normal level on the cold side! I have a box full of those relays I take them out of every fuse panel i replace to keep as spares or other projects.

Re: Headlight relay mod revisited...my way to do it and save some money
 

ok here is the pics i promised keep in mind they are off a Ford but who cares if it works right?!?