I have a 2004 Ram QC and I'm mounting fog lights. My delima is that I figured to power the fogs, all I would need to do is tap into a power source that generates power when I turn on the head lights. I tried taping into the power source for the head lights and I tried taping into the wire behind the switch that powers the bulb. By doing that I believe I'm overpowering the relay and that equals NO MORE POWER. Is there anyway that I can power these lights to come on when I turn on my headlights?

Thanks

 

By over powering the relay and no power, what exactly do you mean? The lights all go out, or there is no difference after you hook them up (lights, yes; fogs, no). Normally you will have a ground wire with the fogs as well. Did you ground them?

 

First off, tapping off the lights to "power" the fogs, is a disaster in the making. You run the risk of burning up the wiring harness. You need a separate relay for the new flog lights. Using a relay, yes, you can have them turn on with your headlights.

You need at least a 30 amp relay, two fuse holders, a 20 amp fuse, and a 10 amp fuse, along with an adequate supply of 12 or 14 ga wire, misc crimp on terminals, loom tubing, and electrical tape.

First thing, is to mount the lights. Sounds like you may have already done this. The 30 amp relay has four terminals. One is number 30. This is the supply terminal and should be fused with a 20 amp fuse and connected directly to the positive terminal of the battery. Just leave the fuse out until everything is wired completely.

Another terminal on the relay is number 85, and another is number 86. One needs to go to ground (it does not matter which one). The other terminal needs to be wired to the headlights (again, does not matter which one, just make sure if 85 went to ground that you use 86 to the headlights). This trigger lead needs to be fused at 10 amps, but leave the fuse out for now. You will need to pull the left (driver's side) head lamp assembly. Look in your owner's manual in the back, it explains how to do this.

Find a white wire with a dark blue stripe coming off the headlamp socket. You need to tap the trigger lead into this wire. Don't worry, this will not pull enough current to overheat anything. The real power for the new fog lights will come direclty through the new relay, from the battery.

Now, back to the relay. There's one terminal left, and it is number 87. This is the load terminal, and will be wired to the new fog lights.

Make sure you put the wires inside of loom tubing to protect them. Wrap electrical tape at the ends to secure the wires and keep them from chaffing at the ends of the tubing. Also, when you tap into the white wire with the dark blue stripe, make sure you tape this well to keep water out. I'd recommend soldering this tap, but you still need to wrap it well. Also, ground the fog lamps close to where they are mounted. I like to ground them individually, rather than together.

Once all the wiring is in, the headlamp is once again installed, check to make sure all your connections are tight. Then and only then, install the fuses. First the 10 amp fuse in the trigger line that taps into the headlight wire. Next the 20 amp fuse into the power lead connected to the battery.

When you turn on the head lights, the fogs will automatically come on. This approach does not use a switch. If you want to be able to keep them from coming on at all, you can install a switch to terminal 87 on the relay, with the other lead from the switch tapping into the headlight trigger wire. Then, only when the switch is "on" will the fog lamps come on with the headlights. Alternatively, you could switch the ground wire from the relay.

Wiring diagram attached.

 

What I mean is that when i tap into the positive wire for the right headlight, niether the fog lights nor the right headlight work. When I disconnect the fog lights from the right headlight, the right headlight works again. I grounded the fog lights to the chasis, so I know its grounded.

Headlights + Fog Lights = No lights
Headlights = Light
Fog Lights to the battery = Constant light

what im looking for is a place to tap in the positive cable to the fog lights so the fogs work only when i turn on my headlights.

Thanks

 

The procedure that Mazz has described above is the correct and safe way to properly hook your fogs into your electrical system. It is the same method used by Hella Lighting Systems when you buy a kit from them to hook up aftermarket driving lights and fogs.
By using the relay to your fogs you aren't endagering them to premature failure due to low power supply, not to mention the increased electrical load on the headlamp wire from your switch in the cab if you don't use the relay. If you follow what he has descibed, the fogs will work perfectly for years to come.


Good Luck, and Happy Wiring

 

Thanks Mazz, that is exactly what i was lookin for.

 

Good description Mazz.