Factory Fogs 1998

[glovemeister]

So I am currently trying to add factory fogs into the truck. Yes, I have searched. I've got the switch wiring behind the dash and the switch.

I'm aware I will need to add relays. My issue is where do the fog harneesses connect? I see a 4 pin connector on the driver/passenger size frame area, next to what I believe is ABS/wheel speed connector or vac lines for hubes. Round with two tangs. Where do your factory fog jumper harnesses connect to?

 

[55trucker]

The fog harness is part of the main headlight harness. There is no sub section. Each side will have a somewhat short harness (approx 16") that hangs down behind the bumper alongside the front chassis to body mounts. If you get under the truck & do not see the two drop-down harnesses then the truck isn't wired for fogs. The fog switch wiring is in conjunction with the headlights & the multi function switch, they will not come on unless the headlights (low) are on. The foglight wiring goes thru the engine bay fuse box. If one wants the fogs to be completely independent of the headlights one has to change the I/P fuse panel source (HOT IN HEAD) & source another fuse that is *ign switched*.

 

[cbxer55]

On Lightning's, to make the "fogs" come on minus the headlights, we just put a jumper wire in between the wire part for the "fogs" and the switch itself. This way, the "fogs" will come in with just the running lights on. Did mine years ago. Also put a toggle switch in the jumper wire so I can turn the "fogs" off if I desire, as they come on as soon as the switch is turned to the running light position. I don't always want them on.

I'm going to be putting a front bumper on with the "fogs". I am just going to wire them myself to a fuse protected toggle switch, as I have done many a vehicle.

 

[glovemeister]

So to update everyone in the future.
Yes these are factory fog wiring connectors. The larger square plug on the driver side is the daytime running module.

For reference here is a picture I found:

 

[glovemeister]

So for fun I just went out and tried it. I'm not seeing 12v with test light at either left or right connector. I have verified that #4 fuse is good, and in place in the engine bay compartment. #8 fuse in the dash panel is good. #8 relay was existing, and #10 was not. I switched my ac relay into the #10 spot, and also switched #8 and 10 to verify good function.

With KOEO, and headlights on or off, and high beams off I cannot seem to get power at the fog light connection. What I am wondering is if the used foglight switch I have installed is bad. I feel it audibly click, the illumination works, but I do not hear any relays clicking. Wondering though if that would only happen with a load on the circuit?

Interestingly enough I tried two volts meters to probe various fuses in both compartments. When I measure across the pins I cannot seem to have a normal voltage reading, ie 12+, I believe the voltmeters are showing less like 0.07. Even on something I know that is not possible to be correct on such as fuse pump while running. I am wondering though if I am measuring current draw/voltage drop when I measure like this?

 

[Uncle Gump]

If you connect both positive and negative leads across the fuse... you are measuring voltage drop across the fuse.

Ground the negative lead and touch each side of the fuse individually and take your voltage reading in each location.

 

[glovemeister]

If you connect both positive and negative leads across the fuse... you are measuring voltage drop across the fuse.

Ground the negative lead and touch each side of the fuse individually and take your voltage reading in each location.

Doh thats right. Thanks for confirming that. IDK why I didn't remember that, only been doing this a bit.

 

[Uncle Gump]

It's all good... we all need a push in the right direction now and then.

 

[glovemeister]

So we are finally getting somewhere.

So on my underhood relay #10. I found the one that is 12v, with headlights/key on. I decided to jumper the two big relay posts. I discovered that I had 12v at the end of my foglight harness, and my green foglight on indicator comes on. For fun I attempted to apply the relay constant, to either of the small two posts. I blew the #4 underhood fuse, which seems obvious.

I discovered an interesting thing though, I can press the foglight switch and it does not change the current, nor does indicator light status change.

I then decided cool, maybe I can get fulltime fogs and shut them down with the headlight switch. I turned off the headlights and no change, I can remove the keys from the ignition and no change, in indicator light on switch or 12v current at fog light harness end.

So as I understand it, this is a negative grounding system. So the switch supplies a ground which then allows the relay to change steady state.

The only thing I can think that I am missing is the aspect of the switch providing a ground for the relay to trip.

 

[55trucker]

With KOEO, and headlights on or off, and high beams off I cannot seem to get power at the fog light connection. What I am wondering is if the used foglight switch I have installed is bad. I feel it audibly click, the illumination works, but I do not hear any relays clicking. Wondering though if that would only happen with a load on the circuit?

Have you wired your *new* foglamp switch according to the schematic?
The *solenoid* side of the relay will not energize unless that circuit grounds thru the foglamp switch.
One can see that the switch has a one way diode in the circuit as well to prevent current feedback to the switch from the battery side of the relay, when the relay closes all of the current flows to just the foglamps & not back to the switch.

 

[glovemeister]

55 trucker. Thank you for the reply.

So I have installed a factory/plug and play switch, in factory underdash wiring, from I think an explorer. Advertised the same fit as a ranger. I didn't see there was a diode.

Evaluating the relay I'm thinking obviously I have 12v in, 12v to lights, a pin that details when it is closed/indicator to light, and a ground. I just cannot seem to get the relay to latch/change states with the factory switch. I would vastly prefer factory wiring, but I am not opposed to using it as an indicator or making it so foglights come on full time with park/headlights.

I suppose my next course of action would be to jumper the switch side of the wiring to see if I can get the relay to close.

 

[55trucker]

I don't really understand why Ford produced the switch wiring in the manner they did......the switch is pressed to close the circuit that allows the *control* side of the relay to ground. When that happens the *battery* side of the relay closes to complete the circuit to light up the lamps. In my opinion there isn't a need for the 2ndary circuit that splices into the harness to the lamps from the switch (pin 6) to the splice S127. There is a voltage drop induced at the coil of the solenoid & a 2nd voltage drop at the dash lamp, & then the circuit goes to ground. To me the 2ndary to the lamps is redundant.

 

[glovemeister]

So here is a bit of an update. Think I wasn't operating with full brain capacity over the weekend...

I went out a jumped the power pins on the switch, expecting to find that my switch was bad. I also messed with the high low/multifunction switch wanting to make sure it was on low mode. I was pleasantly surprised to find voltage at the fog light connector. I then replaced the switch, clicked it and the indicator came on and I had voltage at the harness. Turning off the switch kills the voltage, so I think this issue can be closed. Everything is now working as it should.