Headlight Relay Wiring Harness for 93

[Dave M]

Truck is a 93 3500 2wd auto.



I added a Summit Relay Headlight Wiring harness (LMC Truck and SUVlighting also have them for 94+) to my 97 and was going to do it for my friends 93 but I think the headlight plugs are different between 97 and 93 and so the Summit harness will not plug in. Anyone know where I could buy a wiring harnes or have a schematiic with parts list of how to do it. I have the 93 factory service manual for reference.



I don't want to make my own for someone else and would rather just buy a kit if possible but if someone has a schematic of how to do it or a source to buy one please let me know. Does the dealer sell a kit?



Thanks,

Dave

 

[boatpuller]

The only difference that I know of between a first and second gen headlight switch is the extra contact for the rear cab light, the actual connector that plugs in is interchangeable, I have the second gen switch on my truck as I have heard they are heavier. Is the summit kit just a plug in unit between the switch and wiring? If so do you have the part number, I've been meaning to add relays to mine but just have'nt taken the time, if there is a plugin kit I'd just as soon get that then to have to cut my harness up and add relays.



Thanks,

Caleb

 

[KOG]

I'm not familiar with that kit, but I am familiar with putting relays into the headlight circuit. I think you're probably talking about the headlight plugs being different?

 

[boatpuller]

I misread his post, yes he's talking about the headlight plugs not the headlight switch. My error.

Sorry,

Caleb

 

[Dave M]

Well... the Summit relay harness kit is not available on the site anymore but there are a few other places to get one for the 2nd gen... no listing for the 1st gen... and yeah... the headlight plugs look different... I'm considering getting the harness and replacing the plugs but not sure if it will work or not. The LMC Truck harness for 94-02 Dodge Ram is on page 20 of the Dodge catalog PN 55-9505 and here is the link:



LMC Truck Parts - Page 20



That LMC truck harnesss looks identical to the Summitt one I used and its cheaper... 29. 95... . the harness is at the bottom of the pic. Anyone have a source for the 93 headlight plugs... I'll need 4 to make it work.



This harnees goes in the engine compartment between the headlights and the relays from the harness mount on fender. You unplug the existing headlight and plug it into the harness. Then plug another headlight plug on the harness into the headlight you just unplugged... do the same on other headlight. Run a 12v wire from the harness to battery and find a ground and... vwalaa... you take the headlight load off the headlight and power the headlight thru the relay in the harness directly off the battery instead of thru the headlight swith.



Basically you use the headlight switch to trigger the relay (part of the harness) which now uses the relay output (12v from battery) to power the headlights. The relay current draw is minimal so the headlight switch runs cooler and the headlight get more voltage coming directly from the battery (thru a fuse in the harness).

 

[Paychk]

simple headlight relay wiring

Painless 30816 - Google Search

 

[Dave M]

simple headlight relay wiring



Painless 30816 - Google Search

Thanks for the schematic Paychk. The painless kit is pricey at $163 but that schematic is very clear to understand. .



Dave

 

[boatpuller]

They have a kit for an 80-86 DORF, they use the same headlights as my 93, could be a direct plug in rather than having to modify a later model Dodge one.





Victoria British - Catalog FD - Page 58

 

[Dave M]

They have a kit for an 80-86 DORF, they use the same headlights as my 93, could be a direct plug in rather than having to modify a later model Dodge one. Good catch "boatpuller".





Victoria British - Catalog FD - Page 58

Thanks... . that looks like it might work. All it requires is that the headlight plug be wired the same... if they are they same plug and length is correct then it should work. But... . I kinda hate putting a Ford product on a Dodge... what a world!... hehehe. Its crazy... just so crazy it just might work... . hahaha. The PN discussed below is for Ford 80-86 PN 47-3660 (page 58 of the Ford catalog).



I'll give them a call.

 

[Dave M]

They have a kit for an 80-86 DORF, they use the same headlights as my 93, could be a direct plug in rather than having to modify a later model Dodge one.





Victoria British - Catalog FD - Page 58

I just got off the phone with LMC Truck and they faxed me schematics of the 80-86 Ford harness PN 47-3660 (page 58 of the Ford catalog) and 94-02 Dodge Ram harness PN 55-905 (page 20 of the Dodgr Ram catolog)..... you can search by page on their site. Both cheezy schematics (made in Taiwan R. O. C) are identical but the Ford install notes mention unplugging the 3 prong headlight plug.



Looks like the LMC Truck harness PN 47-3660 will work on the 93 Dodge. I'll order one and let everyone know how it works. The parking lights are not part of the harness but they draw much less current (I suppose) then the headlights so I'm not concerned.



Thanks "boatpuller" for digging up that info. Good idea.



Dave

 

[Dave M]

Just more info (to make this thread complete) of wiring a headlight harness from scratch. This thread shows lots of pics of each step of making a harness with parts lists and schematic... very well done:



Installing Headlamp Relays - Dodge Diesel - Diesel Truck Resource Forums



I also verified from NAPA, what "boatpuller" already determined, that the 80-86 Ford and 93 Dodge use the exact same headlight and 3 prong plug. So it looks like the LMC Truck harness PN 47-3660 ($29. 95 plus $10. 75 shipping=$40. 75 total) for the 80-86 Ford will work for the 93 Dodge.



I ordered it and will update when its installed hopefully this weekend, .



Thanks to all who posted and provide all the info I needed.



Dave

 

[Dave M]

Completed Install of LMC Truck Headlight Relay Harnes on 93

As I have stated, I'm not a 1st gen guy but I'm helping out my friend with his 93 so I've been learning a little about these trucks.



I installed the LMC Ford truck harness mentioned in the post above to my friends 93 and it worked. I added an in-line fuse holder to between the harness relays and battery lead and had to lenghten the passenger side wires (two) by around 2. 5 feet each. I added 1/4 inch and 3/8 inch black split loom to hide the harness better (which had a yellow plastic covering on it) and added a small right angle bracket (with nuts and bolts) I found so I could bolt the two relays together for a neater fit.



I experimented with running the harness in front/top of the radiator (actually in front of the hood latch where the top of grill is screwed onto) but finally decided to run it thru the parking light holes and in front of the radiator to hide and protect the harness better. Here are some pics:

 

[Dave M]

Here are two more pics:



In the first pic you can see the red lead on the right of the battery (+ post) is connected to the inline (black) fuse holder and then thru a white connector and then it routes over to the two relays mounted together (back-to-back) on the fender (the 2 relays with the white plugs below them). I had to cut the 2 ring connectors off the 2 red wires from the new harnes and soldered them into my fuse holder ($4 from Kragen)... . these were to connect to the battery + post but are replaced by my in-line fuse holder.



Then the harness is taped and spli-loomed and becomes a fat black wire bundle (with the new headlight harnes in it) that runs off to the right in the pic and on to the drivers side headlight and thru the parking light hole over to the passenger light. Oh, and yes he needs to clean up the battery posts that are corroded... another job for me to do for him.



You may notice (in the post above) that I black tie wrapped the harness behind the metal tabs that have the plastic lock nuts in them for the bottom screws mounting the grill on to the bottom of the radiator. There was plenty of room to run the wire loom thru the parking light holes without causing interference. I put a piece of fuel hose on the harness coming out of the drivers side hole to protect more against chafing.



Bottom pic is the passenger side headlight where I taped up the old headlight connection (not used) and identified it with a white tie wrap tag so it can be found if needed to revert back. I wrapped black tape around the new headlight plug (see the blue tie wrap around it ) from the harness because the wiring on the back of the plug was too exposed for leaving it to get stuff in it (It was not a great plug but it works).



Thanks to all who helped on this mod. Next is a set of gages for the 93. I just can't stand seeing a truck without an EGT or boost gage and for his auto trans a temp gage. When I get ready I'll post a thread.



Thanks,

Dave