HOW TO: rewire Fog lights to Parking lights

[donald]

Ok - so to avoid confusion with the DRL fog light method, I wanted to create this separate thread. Hopefully this isn't frowned upon to have 2 "how to's" for fog light rewires.
Here is the DRL fog light re-wire method:
how-to-fog-light-mod-run-foglights-sepa ... 55642.html

Anyway - this method still requires you go to into the Relay box just behind the air-box.
The result of this re-wire is that the foglights can be turned on/off whenever the parking lights are activated.
To me - this would make sense, since I'd assume that if you want your fog lights on that you'd want your rear lights on too for visibility.
If you want to control/turn on/off your fog lights independent of EVERYTHING (ie. turn on/off with control of the switch) then this is NOT the write-up for you. Althought you might just hook up the relay to run off of a all-time 12V source (ie. the battery), and then the switch will allow you to turn the fog lights on/off as you please independent of everything.

Sorry - I don't have pictures for the step-by-step, as I am a "spur-of-the-moment" mod'er (ie. I like to do the mod's late at night and not have time to document everything ).

Car:
1. 2001 Qx4 (HID headlamp - yes, this matters, as you will soon see...)
2. 2002 Pathfinder (non-HID) - my sibling's truck

Materials Needed:
1. at least 1.5feet of 16gauge wire
2. at least 1 butt-connector for 16ga wire (and of course a crimper)
3. at least 1 quick-connect(TM) or "T-tap" connector
4. small flathead screw-driver (the very small ones)
5. 10mm socket/box-wrench
6. wire-cutter (large enough to cut 16ga wire)


Instructions:

1. Remove Airbox - simply unclamp the MAF body from the flexible-tube leading to throttle-body. I suggest to do this to be able to route the new tap-wire from Relay-box to parking light, however with some patience you can do without removal of airbox
2. locate relay box.
   
3. you will need to remove just the top-row of relays (the row with the Fog-light relay). This is where the small-head flatheads will come handy. Remove all 6 relays (6 in the Qx4, 4 in the Pathy). You'll need to use the flat-head to press the plastic latch and then slowly wiggle back-and-forth the relay out of the socket
4. unclip the housing - this is a bit hard to describe, but the housing around the bank of relays needs to be removed so that you can access the wires underneath the relay sockets. At the time of this How-To, I don't have a picture. I'll grab a picture tomorrow and post it.
5. return to the Fog-light relay socket and locate which wire is the 12V wire that comes when the headlights are turned on.
   
6. To find this use a Voltmeter set at 20V DC, with the ground/black probe to engine-ground and the hot/red probe to a relay-socket spade, turn the headlights on and see which one reads "12V". It should be the same spade labelled "1" below. IIRC, the wire is a Red-with-blue-stripe.
   
7. Once you confirm that "1" is the 12V that turns on/off with the headlights, then comes the permanent damage you'll do - in that you'll need to cut this wire to disconnect the relay from the headlight. Please, I hope you would have read through these instructions FIRST before attempting ->BE CAREFUL! as you need to cut away from the relay-socket.
   This is what you'll basically be doing.
   
   a. find the "1" wire on leading to the relay-socket. This is the wire that triggers the relay to close allowing you to turn on/off your foglights when headlights have 12V supplied to it.
   b. locate a spot to cut that is FURTHEST away from the relay socket
8. You'll "cap" off the 12V side, and you'll use your butt-connector to attach to the relay-side of the wire you just cut. Take some time here during your initial read-thru to understand why you're cutting.
9. Ok - now you take your 1.5ft 16ga wire and butt-connect it to the relay-socket you added a butt-connector to. Take your time to route the wire through to your Qx4 headlight assembly. If you speak Pathy, then it's just your corner light that needs to come out.
10. To remove the Qx4 headlight assembly, seek the 3x 10mm bolts (actually, 1 nut, 2bolts). The headlight assembly should pop out with no issue. I forgot how to remove the corner light on the Pathy - someone can chime in here?
11. unplug the corner light plug - and on the Qx4 there are 2 wires (pink & black), and on the Pathy there are 3-wires, since the corner lights on the Pathy are also the turn-signal.
12. find the 12V parking light wire. The Qx4 is a bit more obvious, as it's the pink one (but just to make sure I'm not giving you bad instructions - double check and make sure it is 12V when you turn on the parking lights and 0V when you turn them off. Same goes for the pathfinder - you DON'T want to trigger off of the turn-signal and have your fog light blink with your turn-signal.
13. we're NOT cutting the wire to the parking light. We're only tapping into it; with our T-tap connector/quick-connector.
    
14. Take some time to become familiar with the T-tap connector and figure out which side the extra 16ga wire you butt-connected to the relay-socket will go and where/how the parking light 12V wire will be tapped with this connector.
15. When ready - align your 16ga wire to the parking light 12V wire and establish the tap via the quick-connector/t-tap connector.
16. DONE! (sorta) Now for some preliminary checks.
17. replace the fog-light relay (only! since this is the only relay we're checking).
    a. turn off ALL lights, and make sure your fog lights are OFF as expected.
    b. Then turn on your parking lights ONLY (no headlights) and check that your fog lights can be turned on and off.
    c. Now turn on your headlights, and check that you can turn on/off your fog lights.
    d. Now check with highbeams activated and that you can turn on/off your fog lights. If all 4 checks are good, then put everything back together in reverse order.
18. Enjoy! Now you can run your foglights independent of your headlights, and EVEN while your ignition/engine is off.

This is what the additional wire looks like coming out from under the relay-housing/wire-loom:


Um - this is my first "write-up" despite it being a duplicate of another write-up (i.e. the DRL Fog rewire - link is at top).

Please feel free to ask questions, criticize, correct, add, remove, etc to this.
I'll try to take your suggestions objectively

[fueler]

cool man. Only downside (or upside?) is that this mod renders the fog light switch useless, since the fogs now only work with the parking lights.

[ARKQX33V6]

Yes that's right, have you ever wondered why they are wired that way? This tutorial was nicely done but changing the manner of operation does a couple of things.
1- some jurisdictions, fog lights are not allowed to be on alone.
2-The fog lights offer a greater load on the parking lights system

At any rate this modification may be used by others.

Automotive builders in general know the rules about wire, fuses and loads, but unlike electricity rules that govern our lives in our work, house, play the auto section has a tendency to stretch these rules out and often run too close to the limit. And when we modify the electric system of cars and trucks we need to be aware of these limits...many people have no idea and could create havoc with their modifications, unaware of the potential problems and risks they present.

[donald]

cool man. Only downside (or upside?) is that this mod renders the fog light switch useless, since the fogs now only work with the parking lights.

well, the switch should be "after" the relay...
and all that's happening is that the "trigger signal" is being re-routed. So the switch isn't taken out of the picture.

Let's look at it this way:
in the original wiring/setup, when the headlights are turned on, I am able to turn the foglights on or off via the foglight switch. It's the same case even with this re-wire because instead of having the relay trigger off of headlight power, it triggers off of the parking light power.

In other words - the foglights will only be able to turn on/off when the parking lights are activated.
And just like the original hook-up, I am able to turn the fog lights on and off.
In addition, when you switch to high-beams, the parking lights are still on, thus you can still switch on your fog/driving lights

Yes that's right, have you ever wondered why they are wired that way? This tutorial was nicely done but changing the manner of operation does a couple of things.
1- some jurisdictions, fog lights are not allowed to be on alone.
2-The fog lights offer a greater load on the parking lights system

At any rate this modification may be used by others.

Automotive builders in general know the rules about wire, fuses and loads, but unlike electricity rules that govern our lives in our work, house, play the auto section has a tendency to stretch these rules out and often run too close to the limit. And when we modify the electric system of cars and trucks we need to be aware of these limits...many people have no idea and could create havoc with their modifications, unaware of the potential problems and risks they present.

agreed! please note that some states/counties/cities may have laws against running your fog/driving lights alone (ie. with no headlights). I am pretty sure there is a vehicle provision here in California regarding this - but like going over the speed limit, I take my chances and plus, I don't really ever plan to run with only the fog/driving lights on.
I only wanted to do this so that if I'm ever in heavy, slow SLOOOWWWW, and crawling traffic, then I don't have to bug the driver ahead of me, and switch off my headlights, but still have my fog/driving lights active for folks to see me (mind you, I'm talking slow as in 5mph slow!)

as for the power and load... I don't think there's any additional load on the parking lights. I mean, sure, the relay will consume some power just because it's added resistance to the line, but it's not going to be significant enough to start melting any wires - in my opinion of course!

Relays (and not to insult your intelligence - this is more like an aside for anyone listening) work off of 2 separate lines of power
1. what I call the trigger line
2. the power supply line
check this out on HowStuffWorks: http://electronics.howstuffworks.com/relay1.htm
(btw, I had to spend a few minutes on this myself when I first learned about relays)

The trigger line passes through the inductor (which I think is where you're concerned with added load??) creating a magnetic field pulling the switch to on the power supply line to close, thus providing power to the fog/driving lights.
So, in this re-wire method - the trigger line is the parking light power.
The power supply line is coming from the same place as it was before - wherever that is (battery or terminal block?)

Now I will admit that I haven't done any measurements on how much of a load the foglight relay is on the parking lights - but I still don't think it's all too bad (just guessing of course).

I've done this on my 1991 Maxima about 8years ago, and never had an issue with wiring melting. Same method of rewiring the trigger signal from the headlight line to parking light line.

Great input guys! thanks.

[miamiheat3332]

You should write a how to for my 06 sonata limited, i have 3k HID fogs, 10k HID projectors, and then stock highbeams, but i want my foglights on with all of that when i have highbeams on.

Should be a nice Blind fest on the road, but id like something like this to use in heavy fog, and night driving when no one else is on the road.

[donald]

hey there miamiheat (LeBron? jk)

the methodology should be almost the same, except for the Qx4/Pathfinder specifics.

Just look for your fuse relay for your foglights.
There shouldn't be more than 5pins, I'd guess.

Unplug it, and using a Voltmeter, find where the "power-wire" is that is connected to the headlights.
Do this by...

1. find your foglight relay - usually in engine bay someplace
2. unplug your foglight relay
3. test each pin for 12V (i think it's 12V)
   a. turn your headlights on and off and see which pin follows this. So, as you turn on/off your headlights, your voltmeter should bounce between 12V (on) and 0V (off).
   b. there should only be 1 pin that follows the on/off of the headlights - if there are multiple. then STOP and figure out what those wires are.
4. now you've found your headlight power wire and now you need to find your 12V parking light wire.
5. after this you can pretty much follow instructions above

now i need to make the disclaimer that you should double check and understand what you're doing before you go cutting and splicing any whires
I can't be responsible for any damage that occurs - this is only a "suggestion" rather than instructions for you since I haven't seen or worked on a car similar to yours.

[fueler]

you are right, the switch is after the relay so my first comment is inaccurate.

and that stupid for light rule does not apply here in cali so its OK

[esy]

i would be the sibling that donald speaks of.

i've done this foglight rewire a few times (on my old Z32 and my old P11). no fried wires, bulbs didn't burn any faster, however the possibility is definitely there. any modification done to any vehicle has a possibility to cause damage. that's obviously nothing new.

anyways, i discovered something new that struck me as strange the other night. after leaving his house last night after the game, i decided to flip on my highs for s*** and giggles as i pull into my driveway. i notice that i didn't see the yellow hue on the ground anymore as my highs went on (i have the PIAA ion crystal bulbs). got out, flipped on the highs, lo and behold, the fogs went out. gave donald a call and it struck us as strange as the relay should now be powered with the parking lights and they should stay on at all times unless we turn them off. so, we'll be getting back into the relay again to see if there may be an extra wire that may need to be clipped or what not. just an FYI.

[Towncivilian]

i would be the sibling that donald speaks of.

i've done this foglight rewire a few times (on my old Z32 and my old P11). no fried wires, bulbs didn't burn any faster, however the possibility is definitely there. any modification done to any vehicle has a possibility to cause damage. that's obviously nothing new.

anyways, i discovered something new that struck me as strange the other night. after leaving his house last night after the game, i decided to flip on my highs for s*** and giggles as i pull into my driveway. i notice that i didn't see the yellow hue on the ground anymore as my highs went on (i have the PIAA ion crystal bulbs). got out, flipped on the highs, lo and behold, the fogs went out. gave donald a call and it struck us as strange as the relay should now be powered with the parking lights and they should stay on at all times unless we turn them off. so, we'll be getting back into the relay again to see if there may be an extra wire that may need to be clipped or what not. just an FYI.

You need to ground the fog light switch.

[NocturnalQX4]

Ok - so to avoid confusion with the DRL fog light method, I wanted to create this separate thread. Hopefully this isn't frowned upon to have 2 "how to's" for fog light rewires.
Here is the DRL fog light re-wire method:
how-to-fog-light-mod-run-foglights-sepa ... 55642.html

Anyway - this method still requires you go to into the Relay box just behind the air-box.
The result of this re-wire is that the foglights can be turned on/off whenever the parking lights are activated.
To me - this would make sense, since I'd assume that if you want your fog lights on that you'd want your rear lights on too for visibility.
If you want to control/turn on/off your fog lights independent of EVERYTHING (ie. turn on/off with control of the switch) then this is NOT the write-up for you. Althought you might just hook up the relay to run off of a all-time 12V source (ie. the battery), and then the switch will allow you to turn the fog lights on/off as you please independent of everything.

Sorry - I don't have pictures for the step-by-step, as I am a "spur-of-the-moment" mod'er (ie. I like to do the mod's late at night and not have time to document everything ).

Car:
1. 2001 Qx4 (HID headlamp - yes, this matters, as you will soon see...)
2. 2002 Pathfinder (non-HID) - my sibling's truck

Materials Needed:
1. at least 1.5feet of 16gauge wire
2. at least 1 butt-connector for 16ga wire (and of course a crimper)
3. at least 1 quick-connect(TM) or "T-tap" connector
4. small flathead screw-driver (the very small ones)
5. 10mm socket/box-wrench
6. wire-cutter (large enough to cut 16ga wire)


Instructions:

1. Remove Airbox - simply unclamp the MAF body from the flexible-tube leading to throttle-body. I suggest to do this to be able to route the new tap-wire from Relay-box to parking light, however with some patience you can do without removal of airbox
2. locate relay box.
   
3. you will need to remove just the top-row of relays (the row with the Fog-light relay). This is where the small-head flatheads will come handy. Remove all 6 relays (6 in the Qx4, 4 in the Pathy). You'll need to use the flat-head to press the plastic latch and then slowly wiggle back-and-forth the relay out of the socket
4. unclip the housing - this is a bit hard to describe, but the housing around the bank of relays needs to be removed so that you can access the wires underneath the relay sockets. At the time of this How-To, I don't have a picture. I'll grab a picture tomorrow and post it.
5. return to the Fog-light relay socket and locate which wire is the 12V wire that comes when the headlights are turned on.
   
6. To find this use a Voltmeter set at 20V DC, with the ground/black probe to engine-ground and the hot/red probe to a relay-socket spade, turn the headlights on and see which one reads "12V". It should be the same spade labelled "1" below. IIRC, the wire is a Red-with-blue-stripe.
   
7. Once you confirm that "1" is the 12V that turns on/off with the headlights, then comes the permanent damage you'll do - in that you'll need to cut this wire to disconnect the relay from the headlight. Please, I hope you would have read through these instructions FIRST before attempting ->BE CAREFUL! as you need to cut away from the relay-socket.
   This is what you'll basically be doing.
   
   a. find the "1" wire on leading to the relay-socket. This is the wire that triggers the relay to close allowing you to turn on/off your foglights when headlights have 12V supplied to it.
   b. locate a spot to cut that is FURTHEST away from the relay socket
8. You'll "cap" off the 12V side, and you'll use your butt-connector to attach to the relay-side of the wire you just cut. Take some time here during your initial read-thru to understand why you're cutting.
9. Ok - now you take your 1.5ft 16ga wire and butt-connect it to the relay-socket you added a butt-connector to. Take your time to route the wire through to your Qx4 headlight assembly. If you speak Pathy, then it's just your corner light that needs to come out.
10. To remove the Qx4 headlight assembly, seek the 3x 10mm bolts (actually, 1 nut, 2bolts). The headlight assembly should pop out with no issue. I forgot how to remove the corner light on the Pathy - someone can chime in here?
11. unplug the corner light plug - and on the Qx4 there are 2 wires (pink & black), and on the Pathy there are 3-wires, since the corner lights on the Pathy are also the turn-signal.
12. find the 12V parking light wire. The Qx4 is a bit more obvious, as it's the pink one (but just to make sure I'm not giving you bad instructions - double check and make sure it is 12V when you turn on the parking lights and 0V when you turn them off. Same goes for the pathfinder - you DON'T want to trigger off of the turn-signal and have your fog light blink with your turn-signal.
13. we're NOT cutting the wire to the parking light. We're only tapping into it; with our T-tap connector/quick-connector.
    
14. Take some time to become familiar with the T-tap connector and figure out which side the extra 16ga wire you butt-connected to the relay-socket will go and where/how the parking light 12V wire will be tapped with this connector.
15. When ready - align your 16ga wire to the parking light 12V wire and establish the tap via the quick-connector/t-tap connector.
16. DONE! (sorta) Now for some preliminary checks.
17. replace the fog-light relay (only! since this is the only relay we're checking).
    a. turn off ALL lights, and make sure your fog lights are OFF as expected.
    b. Then turn on your parking lights ONLY (no headlights) and check that your fog lights can be turned on and off.
    c. Now turn on your headlights, and check that you can turn on/off your fog lights.
    d. Now check with highbeams activated and that you can turn on/off your fog lights. If all 4 checks are good, then put everything back together in reverse order.
18. Enjoy! Now you can run your foglights independent of your headlights, and EVEN while your ignition/engine is off.

This is what the additional wire looks like coming out from under the relay-housing/wire-loom:


Um - this is my first "write-up" despite it being a duplicate of another write-up (i.e. the DRL Fog rewire - link is at top).

Please feel free to ask questions, criticize, correct, add, remove, etc to this.
I'll try to take your suggestions objectively

I found wire "1" BUT when i put the high-beam on the fogs turn off still. even though i have hooked the wire directly to the battery. This way it was completely independent of the system.

Any thoughts?

[donald]

yeah, this is what TownCivilian refers to in the post prior to yours.
I haven't tried it, sorry for the misdirection/confusion from the other thread.

TownCivilan's post suggests you need to ground the driving/fog lights.
good luck!

[NocturnalQX4]

i would be the sibling that donald speaks of.

i've done this foglight rewire a few times (on my old Z32 and my old P11). no fried wires, bulbs didn't burn any faster, however the possibility is definitely there. any modification done to any vehicle has a possibility to cause damage. that's obviously nothing new.

anyways, i discovered something new that struck me as strange the other night. after leaving his house last night after the game, i decided to flip on my highs for s*** and giggles as i pull into my driveway. i notice that i didn't see the yellow hue on the ground anymore as my highs went on (i have the PIAA ion crystal bulbs). got out, flipped on the highs, lo and behold, the fogs went out. gave donald a call and it struck us as strange as the relay should now be powered with the parking lights and they should stay on at all times unless we turn them off. so, we'll be getting back into the relay again to see if there may be an extra wire that may need to be clipped or what not. just an FYI.

You need to ground the fog light switch.

I am running HIDS and experiencing the same issue here. ANy ideas? you say to grown the light switch, can you give some details?

[NocturnalQX4]

yeah, this is what TownCivilian refers to in the post prior to yours.
I haven't tried it, sorry for the misdirection/confusion from the other thread.

TownCivilan's post suggests you need to ground the driving/fog lights.
good luck!

Hey I figured it out you have to ground the other red and blue wire that goes to pin number 2.

Once I did that I was set. Try it!!

[Drakart]

Just did thiis using an external relay with harness. Got the switch power from the ac when the ignition turns on and just removed the relay for the fog lights and put the wire that get switched on from the relay to the spot that turns on the fog lights in the relay box. Very simple took about 10 minutes with a relay and harness I bought in a 5 pack a while ago.