Rewire fogs to come on with parking lights

[Johnathan M]

Hi, I have a 2013 expedition and I would like my fog lights to be on all the time. FORscan doesn’t seem to have any code to change for Bambi mode for the 2013 expedition, so I’m looking for a way to rewire something to keep the fog lights on all the time that my other lights are on. If they were wired into my parking lights, that would solve my problem. but I’m not sure what the best way is to do it so it doesn’t backfeed through the fog light circuit and so that it doesn’t mess with the computer and throw codes. any help would be appreciated!

 

[Trainmaster]

Can't get into a whole "how to" here, but assuming there's no software way to do this, you'd need a $10 relay. You would energize the relay coil from a parking light and supply the contacts with fused power from the battery to feed the fog lights. This way the existing wiring isn't carrying any load from the fog lights.

 

[Johnathan M]

Thanks for your response. I’ve wired up lights with relays before so I am familiar with that. My concern is do I need to totally separate the fog lights from the existing vehicle wiring? These are factory fogs and my concern was that if I just splice into the factory fog wires with power from the relay, that it would be back feeding power to wherever the fog lights originally get their power from. I guess I could unplug the fogs from the factory harness, and get some harness extensions from Amazon that I could then splice into them directly to the lights. But my question when doing that would be is it going to light up something on the dash or throw some kind of a code if the vehicle is trying to turn on the fog lights and it’s not seeing that they’re coming on because they’re unplugged from the factory harness?

 

[Trainmaster]

I would try it with a jumper and see what happens. Shouldn't hurt anything. Might light the "fog light" indicator on your headlight switch. I think that would be it.

My 2008 fogs are strictly electrical with a mechanical switch. There's no tie-in to any module that I can see and nothing senses a burned out bulb. Can't say your 2013 isn't different.

Some people would put a jumper on the headlight switch, but I'd fear an excessive current draw doing that. That is why the switch is interlocked to turn out the fog lights when the brights are lit. Even using a relay and separate feed to the fog lights, you may want to check the total current drain when the high beams are lit. You may have to wire the fogs to turn off when the high beams go on. You don't want to exceed the current produced by your alternator.

 

[Johnathan M]

I don't care if the "fog light" indicator is on. It is on anyway now when they are turned on. Where are you meaning to put a jumper? From the parking light wiring to the fog light wiring?

Wiring the fogs to be off when the highs are on would defeat the purpose of what I'm trying to do. They currently come on with the lows, and turn off with the highs (factory setup). I want them to stay on with the highs. I live out in the sticks and so do a lot of country driving at night. Highs don't light the road close up or out to the sides. The fogs make it easier to see if there are critters close to the vehicle about to jump out in the road. My thought was if I wire them to the parking lights, then they wouldn't go off when I turn my high beams on. My Expedition uses the same bulb for the lows and highs. It just switches which filament is turned on. So there shouldn't be any more draw when the highs are on then when the lows are on. Also, I have replaced my headlight bulbs with LEDs and am planning on doing the same with my fogs. So they should be drawing less current than the stock setup anyway.

 

[Trainmaster]

By wiring a relay's contacts to feed the fog lights directly from the battery you can be assured of not overloading any existing wiring.

You should still measure the amperage of the high beams vs. the low beams and the LED's vs the stock headlights to assure that you are not drawing more power than used with the stock setup. Or just go for it and see what happens. At worse I think you'd run down the battery.

 

[tommyddsr]

Electrically the correct thing to do is use a relay. Sure you can rig it and it will work but you run the risk of an electrical fire. Respect your rig.

 

[Johnathan M]

I agree. I have no problem using a relay. My main question was if I could just tie the power from the relay into the factory wires feeding the fogs. Didn’t know if that would be an issue if the vehicle would be sending power when the headlights are on low beam, and the relay is sending power at the same time. I may just unplug the factory wiring at the fogs and buy some pigtails for the fogs that I can wire the relay into. I would love to just be able to disable whatever it is that disables the fogs when I turn my high beams on, but I have no idea how to do that or if it’s even possible.

 

[FRANKCVZ]

I have done that in the past on a Chevy Silverado by wiring a diode from the parking lights to the existing fog light relay in the fuse box under the hood. The diode will allow the parking lights to send voltage to the fog light relay and requires very little current because you are merely turning on the relay. The diode will also prevent any current flowing from the fog light circuit back to the parking lights.

 

[intense98neon]

This would not be bambie mode in Forscan. I've done it in Forscan on our 2017, it was under the daytime running lights.



I'm not sure if this is the same for a 2013 though.

 

[Johnathan M]

I have searched and searched for the codes to enable Bambi mode in FORScan but they don’t seem to exist for a 2013 Expedition. They exist for 2015 and up and for many years of F-150s, but none of those codes work on the 2013 Expedition.

 

[lbv150]

Hmmm. My 04 and 16 you can turn on the fog lamps while the parking lamps are on via the normal switch..... coming on with only the headlights defeats the purpose of fog lamps.

 

[Simon Clowes]

Actually even using the same bulb and a different filament there can still be a change in current drawer, which is relate to the wattage of the lit element. Some bulbs have a higher wattage rating for one than they do for the other.

Here is what I would do (by the way radio/electronics tech for over 40 years). Unplug the harness going to one Fog light. if you do not throw any error codes, I would then install the relay and tap into the parking lights for it's activation voltage. Find a matching plugs at your local parts shop and wire them so that the fog light power goes to the switched contact on the relay (sorry without one in front of me I cannot recall the terminal number but think it's 86). The other terminal would go to ground. Now from the supply line direct to the battery. This way, the fogs are isolated from the other lights, but still switched by turning on the Parking Lights.

 

[Goofy173]

You definitely need to cut the original power wires on each. Backfeeding power is never a good idea and cutting them is the better splice than tagging onto the line anyway.

I still think there us a way in forscan but I've never found an expedition spreadsheet. They say use F-150 but I'm not chancing it.

 

[Johnathan M]

I still think there us a way in forscan but I've never found an expedition spreadsheet. They say use F-150 but I'm not chancing it.

I have tried the codes for some other vehicles (including 2013 F-150) but they don’t work on my 2013 Expedition. Also some of the newer vehicles have more digits in that 726-11-01 line of code. Mine only has 4 digits plus the 2 checksum digits. Some vehicles have 8 digits plus the 2 checksum digits in that location. And some of the newer vehicles have the Bambi mode farther down in 726, in areas that don't even exist in my 2013. I don't have it up in front of me now, but I think my 2013 only goes to 726-27-XX, whereas some of the newer vehicles go all the way up to somewhere around 726-51-XX.

If I make a change that I'm not sure will work, I take a picture with my phone of the way it originally was, and then if it doesn't work, I can easily change it back to the way it was. And of course I saved all the AS-Built data prior to doing any work at all in FORscan. I've messed around with it quite a bit and changed several other things, but cannot figure out how to do the Bambi mode on my 2013. That's why I've pretty much given up on that route and am looking into other options to have fogs on with my brights.

 

[Johnathan M]

Hmmm. My 04 and 16 you can turn on the fog lamps while the parking lamps are on via the normal switch..... coming on with only the headlights defeats the purpose of fog lamps.

Mine works the same way... fogs come on with the switch. I'm guessing you didn't read my original post carefully, or maybe I didn't explain myself clearly, but what I'm trying to do is get my fogs to stay on even with high beams. They are already on with parking lights and low beams, but I want them on all the time. They help light up the area directly in front of my Expedition and out to the sides where the high beams don't reach. My thought process in tying them into the parking lights is that the parking lights are on all the time that the headlights are on (including when the high beams are on), therefore my goal would be accomplished.

On vehicles with separate bulbs for highs and lows, this is not as much of an issue. My 2007 MKZ has separate bulbs for highs and lows, and when I switch to high beam, the lows stay on as well, lighting up the road nicely close up and at a distance. But my Expedition has one bulb for both highs and lows, so when I switch to highs, the lows go off and leave me wishing for more light close up and out to the sides.

 

[Johnathan M]

I have done that in the past on a Chevy Silverado by wiring a diode from the parking lights to the existing fog light relay in the fuse box under the hood. The diode will allow the parking lights to send voltage to the fog light relay and requires very little current because you are merely turning on the relay. The diode will also prevent any current flowing from the fog light circuit back to the parking lights.

I like this solution. It doesn't seem like there would be any safety issues and it seems to be the simplest solution that I have heard. Doesn't require messing with any factory wiring. However, I have never done anything with diodes. I know how to solder, have installed extra lights inside and out of my vehicles, installed subwoofers, re-wired entire houses (I'm a remodeling contractor by trade), and so on. But never having done anything with diodes, I have no idea what kind to purchase. I looked on Amazon and it looks like there are many different options. I'd appreciate it if you could educate me on what type of diode I need to purchase so i get the right thing. Thanks!

 

[tommyddsr]

Hopefully someone has mentioned to you that it is illegal to have your fog lights on with your high beams in some states. That is why they are wired as they are from the factory. Just thought I would mention it......

 

[Dennis_H]

Maybe add a switch inside in series with the relay trigger to turn them off if needed... (like inspection)

 

[Goofy173]

Maybe add a switch inside in series with the relay trigger to turn them off if needed... (like inspection)

That's what I do with my off-road LEDs behind the grill. I 3D printed a switch mount that is installed on the turn signal stalk so I can access both the high beams and LEDs with just my left hand.