crazzywolfie

i thought they used a the 3rd filament in the sealed beam light. if you apply power to the high beam terminal and ground the low beam terminal you get this dim light that comes on. i thought that is how dodge did it but i have not got a chance to check yet since it is a tiny bit too cold out especially with the wind.

crazzywolfie

i was thinking if i had to i could just cut the high and low beam wires that go to the DRL module and hook it directly to the to the headlights. then the DRL would not be on relays but you could still use relays to give the lights full power when you turn the switch on.

j_martin

Living just below the 49th parallel, I don't have any first hand knowledge of how the DRL works.

I can't find any theory of operation in the service manual.

Looking at the wiring, it gets power with key on, power through the headlight switch breaker, and a signal from the VSS.

The headlamp switch breaker supplies the power for the lamps
The Key on power (A21) says the key switch is on.
The VSS signal says the truck is moving.

I would assume it supplies power to the headlamps, apparently both filaments, through a resistor or zener diode and a blocking diode to each filament from the headlight switch. That way if full power is supplied to the headlamps through the regular switching, it doesn't back feed into the DRL module.

So now that I've actually looked at the diagrams and made a reasonable attempt to understand the logic, I will change my recommendation.

Hook the violet and red/orange wires from the DTR to the headlamp connectors. (at the lamps) like this


hope it helps

Jungle

Jim,
I was looking over the wiring schematic for this setup & there seems to be 3 head lights on the wiring schematic. Can you please explain? I'm gathering parts now to do this on my RCs & was getting a little confused on the wiring schematic.
Thank you for the awesome info!!
Jim

bannerd

The third headlight is the trigger wire. Basically you would plug in Jims whip into the the driver side headlight. I suppose you could clean it up and cut the wire out and splice into it. The way jim shows, it would be the most simple way to install the wire whip. From there you would plug the headlight socks into your right and left lights.

Jungle

Thanks for the info!!!
I see that now, but when I was looking at the drawing I was thinking about replacing the old setup with the new & splicing in at the fender well where the relays go.
Thanks,
Jim.

Jim Lane

Thanks Guys,

I made the harness this way so it would be easy to revert to the original headlamp wiring if ever needed in the event of a relay failure.

I do not like to cut out factory wiring, I have had to repair some pretty hacked up harnesses in my journeys.

The important message here is use good relays like Bosch, Tyko, Potter Brummfield, Omron, Hella, stay away from the cheap ones sold at the auto parts for fog light installs. (Blazer)

Jim

bannerd

So napa here is out of 12 gauge wire, they won't be getting some rolls for another two weeks. I went to an electric place and they have a philips roll that napa had (they cut the length you need for a few dollars $8 for ten feet).

http://www.napaonline.com/Catalog/Ca...131_0218264247

What do you guys think of this? I don't know what napa uses for wire but it is good quality and is made in USA. The stuff from lowes was thin and didn't flex as much as the napa wire.

Jim Lane

I think NAPA used to sell wire made by Belden, any good brand of wire will be ok And it should be listed as "Automotive"

Automotive wire will have more strands than THHN building wire.

Stay away from any wire that says "Plastic" for the insulation.

There are many kinds of wire out there each with a specific purpose including Hypalon, Teflon, Nylon, Silicone and even Cloth to confuse you.

I have rolls and rolls of wire from Noco, Packard and Belden

Jim

haultruck

Jim, this thread is awesome. Good, easy to follow instructions/ pictures. I would have never tried this without it. I have my harness built, but have not plugged it in yet because I have so much to do to fix the factory wiring first. ( Probably get some questions out of me as I do) I have two simple questions about the relay system. 1. Can I use 4 pin relays without the middle 87a terminal? I only ask because I already have 3 of them, and I don't see where you plugged anything in to it. 2. I plan on leaving factory alone as you did, and was wondering what you did with original headlight plugs when finished. Tape em up and zip ty them out of the way? Any replies would be appreciated. Thanks

Jim Lane

#1 Yes you can use the 4 terminal relay, Term.#87a in the N/C terminal and is not used at least on this circuit.

#2 The original harness is just tucked behind the headlamp bucket and zip tied, I am using the drivers side as the trigger for the relays, the 4 relays sit behind the battery although I need to move them or install a deflector because of the water that runs down the hood.

Jim

haultruck

Thanks for the reply Jim. That's the answer I was hoping for. Now there's nothing to it but to do it.

crazzywolfie

i got a bit of an idea. do you think it would be ok to wire pin 87a on the low beam relay to the pin 87 on the high beam relay. then use pin 30 on the low beam relay to go to the low beam light and connect pin 87 to the battery. if it is ok to wire things this way then you would not need a 3rd relay or diode to turn the low beams on while the highs are on. just more power would be pull through the high beam relay but not really much more than they should be able to handle. having your high and low beam on at the same time should not pull more than 22 amps. most relays are usually good for 30 or 40 amps.

bannerd

Helping a buddy install his headlight relays, he didn't hook up a ground to ground to the body of the truck. Said it wasn't a big deal because he grounded the battery. Is this right? Not getting anything out of the lights.

crazzywolfie

i just thought i would share this info everyone. the relay harness and daytime running lights do not play nice with each other. the 4v or so that the daytime running lights module puts out is enough to cause the high beam relay to chatter. i don't know a lot about relays but i think i remember reading that chattering can cause them to wear out quick.