Discuss How To: Fog Light Wiring

FireRanger · #1 10-09-2009, 08:40 AM

I was going to copy this over from R-F where I originally posted it but....

This how-to has wiring diagrams for three different ways to control auxiliary lighting devices. Typically this fog lights, driving lights, off-road lights, or back-up lights. The concept can be applied to anything.

You should always use but connectors and insulated spade connectors for your connections. Do not ever use household wiring type wire nuts to twist wires together. Fuses and proper wire gauge are very important, cheaping out on this step could set your truck on fire.

#1: Controlling lights with a switch
The lights are turned on and off only by a simple switch in the cab. This is the most common. I recommend getting power for the switch from a circuit that is only on when the ignition is on. That way the lights will never be left on while the engine is shut off killing your battery.

#2: Controlling the lights with an existing circuit such as high beams or reverse lights.
This will slave your new lights to the existing lights. I do this all the time with my off-road lights so they come on and off with the high beams. That way I don't have to push buttons to turn them on and off. This is also what you would do with reverse lights.

#3: Controlling the lights with both a switch and an existing circuit (on-off-automatic)
This is a combination of both. With a SPDT center-off switch, you can have both worlds. With the switch in position one, the power flows like diagram #1. With the switch in position two, the power flows like diagram #2. With the switch in the middle, the lights are off.

turbo · #2 10-09-2009, 11:32 AM

I'll make the same comment I made over on R-F:

I prefer running a ground wire from the relay to the in-cab switch, in situations such as you show in diagram 1, and applying power to the relay coil under the hood. That way, you have a "ground wire" going through the firewall and the in-cab switch merely completes the ground circuit to energize the relay. If, for whatever reason, that wire gets frayed going through the firewall, the worst that will happen is that your auxilary lights will illuminate; wired as you show it, if the wire going through the firewall gets frayed and shorts, you'll blow the in-cab fuse (repeatedly, until you find/fix the short).

...also, the stock Ranger foglight wiring is done by providing relay coil ground from the in-cab switch, as well.

FoMoCo · #3 10-09-2009, 11:55 AM

Quote:

Originally Posted by turbo

I'll make the same comment I made over on R-F:

I prefer running a ground wire from the relay to the in-cab switch, in situations such as you show in diagram 1, and applying power to the relay coil under the hood. That way, you have a "ground wire" going through the firewall and the in-cab switch merely completes the ground circuit to energize the relay. If, for whatever reason, that wire gets frayed going through the firewall, the worst that will happen is that your auxilary lights will illuminate; wired as you show it, if the wire going through the firewall gets frayed and shorts, you'll blow the in-cab fuse (repeatedly, until you find/fix the short).

...also, the stock Ranger foglight wiring is done by providing relay coil ground from the in-cab switch, as well.

i was just about to say that

FireRanger · #4 10-09-2009, 01:40 PM

That is good practice but it limits what you can do with the switch. I like to pull power for my switching for various places to make it more custom, such as from an ignition switched circuit. That way thing shut off with the ignition regardless of the switch being on or off.

turbo · #5 10-09-2009, 09:43 PM

Matt -- that's true. ...and, if that's what you want/need for a specific situation, then just use a second relay inside the cab, powered by the ignition +12 to switch the ground to the foglamp toggle circuit.

Puredreamz · #6 09-20-2010, 05:45 PM

i got a 95 ranger just wanna make sure i ve got two wires on my fog lights a black with a white strip and a all black. I m assuming the white strip is positive and the all black is negative can anyone verify

turbo · #7 09-21-2010, 05:19 AM

Quote:

Originally Posted by Puredreamz

i got a 95 ranger just wanna make sure i ve got two wires on my fog lights a black with a white strip and a all black. I m assuming the white strip is positive and the all black is negative can anyone verify

that would be in keeping with standard automotive wiring, yes.

if the body of the fog light doesn't electrically contact the vehicle's ground system, then the polarity doesn't really matter -- either wire can be connected to + or - ...usually, though, the solid black is the ground wire.

Puredreamz · #8 09-21-2010, 05:42 AM

thanks

06ranger · #9 09-21-2010, 12:36 PM

I'm trying to wire in factory fog lights on my ranger that was not equipped with, i have a 2006 Ford Ranger 3.0 Auto, manual mirrors locks and windows. I yanked a harness from a 98 explorer 5.0, i have the wires run, and need help hooking them to the factory fog light switch, any help would be greatly appreciated

i also got the switch out of the explorer, and had the wiring behind the dash but no wiring under the hood for it. I have the ground already figured out for the lights just need help getting power to the lights through the switch and most likely a relay or 2

drummerboy11 · #10 10-16-2011, 11:38 AM

hey fireranger, this might be a stupid question, but is there a way i can run six lights through my highbeams? well not all six lights, but have 3 switches (1 for every 2 lights) connected to my highbeams so the only way theyll turn on is if the highbeams are on. if you can, pm me cuz i have a few more questions

FireRanger · #11 10-16-2011, 11:44 AM

Yes. Just use the high beam circuit as the power source for the three switches. Look at diagram #3 and just ignore the alternate source of power and use a normal single pole single throw switch. Do that for each group of two lights.

drummerboy11 · #12 10-16-2011, 08:01 PM

can you have one single wire routed to all three switches from the highbeams?

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in other words, is this wiring possible or safe:

FireRanger · #13 10-17-2011, 02:40 AM

Well what you drew is the opposite, one switch running three relays. But I know what you mean. Yes, one wire from the high beams can go to all three switches.

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drummerboy11 · #14 10-17-2011, 09:13 AM

Thanks for all the help! LasT question: would I need to change any of the fuse sizes? Seeing as i changed the setup?

FireRanger · #15 10-17-2011, 11:35 AM

Nope. Not in this configuration.

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