Help.... keep burning up factory fog/driving light switches

Ok so ive got the factory fog/driving lights hooked up and working fine on the factory fog/driving light switch... no issues there

1995 Ford Ranger XLT Ext-cab 4.0L Automatic

Here is the issue(s) i am having
Needing to add aftermarket lights to my brush guard and ive added another Factory fog/driving light switch and cut hole in radio face plate and mounted it....

Issue i am having is that it keeps burning up

Here is my wiring so far

Hot wire from ign source to factory (added on) switch (seperate wire and source)
Grounded (spliced into factory wire next to factory switch)
Dash lights connected to switch (spliced into factory wire next to factory switch)
Then hot out to 40 AMP relay under hood of truck (seperate wire out to the relay)

Problem is the switch keeps smoking (frying, burning up) and has no output yet the factory one to my fogs works just fine??

Is there a step i am missing?? I mean there is a hot in, a ground, and a hot out to relay, (and of course the dash lights) what am i missing or adding to much??

Seems to be wired JUST THE same as the factory one???

Help please this is driving me nuts ive gone through three switches already and its frustrating. ...

Hope the pictures posted
Show you how it is wired

Your explanation doesn't tell us what all the wires are hooked to. Also, what do you mean "smoking"? Are you frying the switch contacts, or the bulb?

There are two separate circuits inside that switch, and it doesn't work if you get them crossed.

Clarify what kind of failure your having, and I'll walk you through the troubleshooting steps to find the problem. You'll need, at the very least, a 12V test light of some sort, and a multimeter would be even better.

As you can see in the picture the black is the ground spliced into factory harness

The light blue and red are spliced into for dash lights into factory harness

The blue and black is seperate wire ran to a 12V ignition source (hot when ignition is turn on)

The tan and orange is ran out to the 40 amp relay under the hood (to feed power to my aftermarket lights)

The switch is smoking burning them up not the bulbs the switch three of them like ive got them shorted or crossed wired?? (Does not pop fuse anywhere)

As you can see in the pictures at one time i had all three wires spliced into factory harness of of original switch

The issue is i am not getting power out of the tan orange wire to my relay
And the light that lets you know the switch has been turned on is not lighting up
But the dash light is working fine on the switch

The bottom switch is for the factory fog/driving lights

The top one is for my aftermarket brush guard lights

I have both test light and a DMM for testing

Let me know if needing more information

The factory wire harness colors are as follows

Blue and black are hot when head light is turned on

Black is the ground

Red and black is the dash lights

Tan and orange is hot out to factory fog/driving lights

This is all i am assuming as tested with my DMM and light probe

Maybe a better picture of the factory wire harness

The one with the yellow clip on it is the factory harness

The gray on missing the yellow clip is the one i am trying to add

Hope those help??

Okay. I see the source of your problems right there. (You know what we get when we assume...)

Your factory fog light circuit does not work by supplying switched 12v to the relay, which is grounded on the other side of the coil, as you would expect. It works by supplying a switched ground to the relay, where the other side of the coil is 12v (switched with the headlights).

Basically, that lt blu/blk wire is sometimes a short to ground.

If you're going to use that switch, you need to wire it up like the factory switch, and you're going to have to rewire your new circuit.

Go to www.autozone.com, register for a free account, and then add your vehicle in the top center of the screen. Then, in the orange bar below that, hover over "Repair Help" and click "Vehicle Repair Guides". In the center of the screen, click "Chassis Electrical", then in the "Select a Chapter" box on the left, click "Wiring Diagrams". Scroll down to Fig. 38 and click "Enlarge". The wiring you want is in the top left corner.

Let me know if that makes everything obvious, or if you need further instructions.

will do thanks SPOTT

My first thought is that you have over worked the switch. It most likely it isn't prepared for a 40 amp breaker.
Most likely that switch is good for a max of 10 amps. I could be wrong but that is my first thought.
Big Jim

I have those wiring diagrams

made no sense to me,

can you help explain in simpler terms?? or even a diagram of what wire goes where ??

Thanks

Big Jim M said:

My first thought is that you have over worked the switch. It most likely it isn't prepared for a 40 amp breaker.
Most likely that switch is good for a max of 10 amps. I could be wrong but that is my first thought.
Big Jim

Click to expand...

Not even close. It's a 40A relay, not a breaker, and the relay is handling the 40A, not the switch. The switch supplies around 20mA (that's 1/50th of an amp) to trigger the relay, and it can handle that easily.

We've found the problem, it turns out the wiring is completely different than what you'ld expect.

how should i be wiring this into the switch??

can you help with explanation

i sure could use the help

Okay, letsee.

First, you need to take the new relay out of the socket. Find the terminals that hooked to ground and the (supposed) 12V signal from the switch.

Set your DMM to measure resistance (ohms) and get a reading between those two terminals, then swap the probes and get another reading across the same terminals. If they're the same, then life is a little simpler. If one direction reads really high resistance, or an "open" circuit, then we have to be careful about which way we hook it up.

Also, check the base of the relay for little cast numbers, like 85 and 86 and 30, and let me know if you find them.

Let me know what you find, and I'll make an explanation.

Also, what kind of control do you want with these new lights? Do you to be able to turn them on any time you like, or only when the headlights are on (both high and low beam) or only when the low beams are on (like the current fog lights)? Or maybe only when the high beams are on?

if i did not explain before i am trying to wire these up so i DO NOT need my headlights on or my brights on to operate them, i would like the option to turn them on at anytime

Thank you

kay, letsee.

First, you need to take the new relay out of the socket. Find the terminals that hooked to ground and the (supposed) 12V signal from the switch.

""I am mounting a separate 40-AMP Relay for the aftermarket lights
I am not using the factory relay under the hood, and not using the factory fuse for the factory fog/driving lights""

Set your DMM to measure resistance (ohms) and get a reading between those two terminals, then swap the probes and get another reading across the same terminals. If they're the same, then life is a little simpler. If one direction reads really high resistance, or an "open" circuit, then we have to be careful about which way we hook it up.

Also, check the base of the relay for little cast numbers, like 85 and 86 and 30, and let me know if you find them.

"the way i understand the wiring for the relay is
30 is hot from battery,
85 is ground
86 is from switch that i am trying to wire in
and 87 is out to the aftermarket lights
i have not wired the relay up at this time until i correct the issues i am having with the switch"


"the relay i added for the aftermarket lights has not even been connected yet i have just ran the dash wire splice, the ground wire splice, and the ignition hot , and the out hot to the after market relay under the hood"

Let me know what you find, and I'll make an explanation.

Also, what kind of control do you want with these new lights? Do you to be able to turn them on any time you like, or only when the headlights are on (both high and low beam) or only when the low beams are on (like the current fog lights)? Or maybe only when the high beams are on?


" trying to wire these to use at anytime on its own circuit"

>>>>

The advice Spott is givin you is good info, here's a diagram that I used on my 93 as I wanted my fogs to be useable at anytime:

Link to the thread if you wanta check it out>>>
Fog light switch wiring diagram

Okay, that info works. We need to wire the relay up differently than the manufacturers of the lights expected, but it will still work properly and be safe. Lets see here...

The black wire on the new switch connects to ground (I think you have that taken care of already, if it's hooked to the black wire on the old switch).

The Lt Blu/Blk wire on the switch connects to terminal 85 on the relay.

The Tan/Org wire on the switch connects to terminal 87 on the relay, which also connects to your new lights.

Terminals 30 and 86 on the relay both connect to constant 12V from the battery (or the power distribution rail) and you should have a fuse in that wire (the manufacturer probably supplied one, or at least specifies one in the instructions).

The last wire on the switch (blue/red or red/black) for the dash lights is already correct, I think.

Heatshrink is a great way to make your connections, are you soldering the wires together beneath?