I searched the previous posts for a couple of hours and haven't found what I need.

I am replacing the factory fog lights on my 1999 Ram. I would like to use the fog light switch that is made into the headlight switch. Is this practical? I have not had any problems with the switch as it seems some have.

The problem I am having is with how this circuit is made. I expected to simply splice into the hot line for the OEM connectors and use that as the supply for the relay that came with the new lights. No so! I have found that this wire is hot all the time and after connecting both old lights in for troubleshooting I found that both wires are hot. Found some good info on the relay/circuit but I'm still a little lost. I'm wondering if I can take the fog light relay out of the PDC and put a jumper in and/or take power from there to the relay that came with the new lights.

I am beginning to wonder if the headlight switch is on the ground side of the circuit since everything is already hot.

Thanks for all help.

 

Based on the 2001 FSM, the fog lights are grounded through the light switch (lame!).

If I were doing this... I would use a separate relay. I would use the wire that is connected to the "85" terminal of the factory relay (brown/yellow) as the ground for the 85 terminal on your new relay.


On your relay:
86 - +12V (control side, doesn't need to have a huge current capability)
85 - The brown/yellow wire from the 85 terminal on the factory relay.
30 - Fused +12V for the new fog lights, preferably directly from battery.
87 - connect to the +12V on your new fog lights.

Ground your fog lights somewhere near the bumper where they are installed.

That should allow you to use the factory switch, without worrying about too much current through your factory switch.

You can dismantle the PDC, and use a wire-tap to get to the brown/yellow wire. It is kind of a pain, but it makes for a clean install. I did that when I hooked up my reverse lights (but I was tapping a different wire ). Just make sure you disconnect the battery first!

Good luck,
Cartman

 

Eric,

Thanks for the intelligent info. I was worried that might get some generic "just cut the old connectors off and use that" from someone who doesn't know what they are talking about. I do have the new kit relay installed. I didn't want to involve the OEM circuit any more than I had to other than hopefully to use the switch to control them. After I started working on this I did think that maybe the switch was on the ground side which threw my original plan completely out the window.

Is there a safer way to find the 85 wire other than getting in the PDC bundle? My fingers aren't quite as nimble as they used to be and I'm a little concerned that I might pull something else loose. Probably not, but...

I guess the easiest way would have been to completely ignore the factory switch and just install the lights from scratch, like I would have on fog/driving lights and CB radios thirty years ago.

Thanks again,
Richard

 

There are a couple of different places you can get it...

I recommended the PDC because it is already under the hood. But you could also easily find it on the back of the headlight switch. It should also be on the "C134 connector, which is the longer rectangular looking connector near the steering column. If you don't want to dig into the PDC, the headlight switch is still the best place to find it.

Have fun!

Cartman

 

Eric, that's EXACTLY how I wired my 130 watt Off Road lights. I almost never use my fogs unless I'm off road where I may find an unfriendly cypress stump at night, so I used a relay and wired 85 to 85 on the fog light relay.

now the factory switch controls both. I used a very thin wire, I am guessing about a 20 gauge as I understand that only about .3 amps goes through it.

I also used the same size wire to tap into my high beam relay so they don't shut off when my high beams get turned on.


I may undo it though. I picked up a wireless relay for my Off Road lights on my Jeep. Came with two key fobs and I also programmed my unused buttons #2 & 3 on my Homelink to control lights on/off. So again, I didn't need to mess with running a switch.

I like being able to turn the Off Road, 130 watt lights on/off if I am using the winch, without having to go back and forth inside the vehicle. This way I can see at night where to run the cable to, without breaking my neck or stepping on a moccasin, but at the same time am not blinded when I'm standing at the winch. So I am thinking of investing another $14 and getting a wireless relay for the truck as well...

 

The control side of the relay (85 & 86) really does not pull very much current. The current is much higher in the other terminals since it that is the side powering your device.

That looks like a pretty sweet setup you got there Hammer! I may have to look into those wireless relays... would be nice to add to the train horn.

Cartman

 

Amazon.com, I wanna say just under $15 shipped.

It's only a 15 amp relay, plenty for a set of Hellas, but not enough for my 130 watt lights. I could find a boatload of 6A wireless relays (?), but 15A was the max. So I picked up a five dollar 40A relay and used the wireless simply to "turn on/off" the 40A relay.

 

Quick question-

When you guys say tap into the relay, exactly how do you mean to do this? I presume you mean to tap the wire from the relay somewhere along the circuit? Just something I haven't had the opportunity or need to do.

Getting to the headlight switch seems a little trouble to me. Have to take off several dash pieces and disconnect the parking brake release and then reach up into the dash. Or am I going the wrong route?

Hammer- SWEET!

 

I've gone through this circuit before and, the grounds are switched while the B+ is always live. This is the standard method of switching power ON/OFF. FYI

CM

 

This is what I like to use:



It is a way to connect two wires together without having to cut, solder, etc. In the picture above, the black wire would be the factory wire and the red would be the wire to the control side of your relay.

Cartman