electrical experts: help modding oem fogs to parking lights
06-27-2005, 01:06 PM
#1
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electrical experts: help modding oem fogs to parking lights
the faq guy needs some help! (yeah yeah, laugh it up haha) i tried wiring my oem fog lights to turn on with the parking lights over the weekend, but i'm definately not the best at knowing how to wire up a car and to know why that what i'm doing is not working.
ok, the tc does include a relay. it looks just like the relay in the picture below. if you look at this wiring diagram, you will see a wire that comes from the front headlights (labeled as +S). the wire is gray and it goes to the #86 point on the relay. there is also a blue wire that goes from the low dimmer switch (labeled as LFG) that goes to the actual switch.
now, based on the picture below, i thought i would be able to just ground the gray wire as shown in the pic below and attach the blue wire to the parking light wire at the switch on the steering column. but when i do that, it actually turns ON the parking lights and i can control it with the fog light switch. does anyone know why this is happening?
does anyone know what i'm doing wrong? i mean, based on the pic, it looks like i'm hooking everything up correctly, but it sounds like i'm not attaching the blue wire to the parking lights correctly or something. any help you guys can provide, i would appreciate it.
ok, the tc does include a relay. it looks just like the relay in the picture below. if you look at this wiring diagram, you will see a wire that comes from the front headlights (labeled as +S). the wire is gray and it goes to the #86 point on the relay. there is also a blue wire that goes from the low dimmer switch (labeled as LFG) that goes to the actual switch.
now, based on the picture below, i thought i would be able to just ground the gray wire as shown in the pic below and attach the blue wire to the parking light wire at the switch on the steering column. but when i do that, it actually turns ON the parking lights and i can control it with the fog light switch. does anyone know why this is happening?
does anyone know what i'm doing wrong? i mean, based on the pic, it looks like i'm hooking everything up correctly, but it sounds like i'm not attaching the blue wire to the parking lights correctly or something. any help you guys can provide, i would appreciate it.
06-27-2005, 03:29 PM
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Instead of splicing into the switch for relay power, you could splice into one of the gauge illumination wires. The coil side of a relay is not enough current draw to effect the illimination wiring.
OR
I'm not sure, but the parking lights could be switched on the ground side, not positive. You just need to then put B+ to 30 and 85, then splice 86 into the ground circuit for the parking lights.
OR
I'm not sure, but the parking lights could be switched on the ground side, not positive. You just need to then put B+ to 30 and 85, then splice 86 into the ground circuit for the parking lights.
06-27-2005, 03:52 PM
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If it were mine, I would buy a $5 relay for the fogs. Just buy one that will handle the curent. Most every parts store will have them in stock. Power the relay off of power going to the parking lights, ground one side of the fogs and switch the power wire going to the fogs with the normally open relay contacts. Then you will have an isolated circuit for the fogs (just remember to add a fuse as well). I dont reccomend powering the relay off of the guage illumination. The gauges use leds which draw somewhere in the range of 20 - 30 mA a piece. A typical fog light relay draws about 80mA if I remember correctly. If the circuit for the illumination does not power anything else then it is designed for X number of 30mA loads... your relay looks like almost 3 of these extra loads.
Another reason is that the solid state circuitry for your gauge illumination is most likely not designed to protect against the back emf spikes created when a coil field colapses. This means when you turn off a relay, you produce a significantly large voltage spike that is opposite in polarity from the original applied voltage. (this is how an ignition coil produces the 40k - 100k Volts that fire spark plugs). The solid state drivers that are used to power the LEDs are most likely not protected against this. Always power additional relays to the load side of existing circuits, and only if that circuit can handle the additional relay. 80mA is not much compared to the several amps the parking light circuit is already designed for. So the built in headroom should more than account for it. The relays are cheap and durable.
Another reason is that the solid state circuitry for your gauge illumination is most likely not designed to protect against the back emf spikes created when a coil field colapses. This means when you turn off a relay, you produce a significantly large voltage spike that is opposite in polarity from the original applied voltage. (this is how an ignition coil produces the 40k - 100k Volts that fire spark plugs). The solid state drivers that are used to power the LEDs are most likely not protected against this. Always power additional relays to the load side of existing circuits, and only if that circuit can handle the additional relay. 80mA is not much compared to the several amps the parking light circuit is already designed for. So the built in headroom should more than account for it. The relays are cheap and durable.
06-27-2005, 04:32 PM
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thanks for the reply guys.
and sorry that i'm so naive here, but if i were to connect B+ (B+ looks to be the orange cable that comes from the 15A fog lamp fuse) to 30 and to 85, do i still keep my fog switch connected as well (which is connected to 85)? or am i removing the external switch from the equation and just allowing the parking lights to turn them on?
and sorry that i'm so naive here, but if i were to connect B+ (B+ looks to be the orange cable that comes from the 15A fog lamp fuse) to 30 and to 85, do i still keep my fog switch connected as well (which is connected to 85)? or am i removing the external switch from the equation and just allowing the parking lights to turn them on?
06-29-2005, 04:09 PM
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i somehow did something similar (using the factory relay), i did use the 12v from illumination, but the fogs stayed on all the time and weren't controllable by the switch. it also popped the standard (i think 7.5A) fuse. since then, i've put the project on hold until i understand a little more about how things work.
06-29-2005, 04:44 PM
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Here is a better description of how I metioned to do it above. I am a big fan of having add on systems isolated from everything else.
1) Add a fog light relay. They are very cheap and can be purchased at virtually any auto parts store. You could be even more creative and try to find a relay that may fit in an open spot in the relay center.. but this would be more expensive and require that there be an open spot.
2) Tie the + relay control to the existing parking light power circuit (the wire actually powering the parking lights).
3) Ground the other side of the relay control coil.
4) Run a new power wire from a constant bat + source to one side of the NO relay contact (include a fuse holder and proper sized fuse for the fogs)
5) Run the other side of the NO contact to the fogs.
6) Tie the fog ground wire to a good grounding point.
I figure this will cost around $20 and will work perfectly. You will have it properly fused, not adding additional load to an existing circuit and not tied into existing control circuitry. If you still want the option of turning them off, route the load side of your NO relay contact through the existing fog light switch on the dash. As I said before, this is exactly how I would do it on my own car.
1) Add a fog light relay. They are very cheap and can be purchased at virtually any auto parts store. You could be even more creative and try to find a relay that may fit in an open spot in the relay center.. but this would be more expensive and require that there be an open spot.
2) Tie the + relay control to the existing parking light power circuit (the wire actually powering the parking lights).
3) Ground the other side of the relay control coil.
4) Run a new power wire from a constant bat + source to one side of the NO relay contact (include a fuse holder and proper sized fuse for the fogs)
5) Run the other side of the NO contact to the fogs.
6) Tie the fog ground wire to a good grounding point.
I figure this will cost around $20 and will work perfectly. You will have it properly fused, not adding additional load to an existing circuit and not tied into existing control circuitry. If you still want the option of turning them off, route the load side of your NO relay contact through the existing fog light switch on the dash. As I said before, this is exactly how I would do it on my own car.
06-29-2005, 11:03 PM
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i understand where you're coming from engifineer. i'm trying to do this with as much "factory" stuff as possible. my only problem now is tracking down a power lead off the tail lights. i don't have a lot of electrical experience, but here's what i've done so far:
the grey wire off the fog light wiring harness is the one providing 12V to the coil of the relay. thats only hot when the headlamps are on. when the fog light switch is pressed, it creates the groud connection for that... experiementing with that grey wire, if i give it 12V from an always hot orange wire, the headlamps come on (as do the fogs). i want to clip that grey wire and in place of that run power from the park light 12V, my problem is FINDING one. i've looked at wiring diagrams to no success and also tried probing around. once i find that then i'll have a simple one wire mod that should allow the fogs to work with the park lights.
the grey wire off the fog light wiring harness is the one providing 12V to the coil of the relay. thats only hot when the headlamps are on. when the fog light switch is pressed, it creates the groud connection for that... experiementing with that grey wire, if i give it 12V from an always hot orange wire, the headlamps come on (as do the fogs). i want to clip that grey wire and in place of that run power from the park light 12V, my problem is FINDING one. i've looked at wiring diagrams to no success and also tried probing around. once i find that then i'll have a simple one wire mod that should allow the fogs to work with the park lights.
06-29-2005, 11:46 PM
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HA! ok, i figured out the best way to do it. i now have my fog lights coming on when the key is in the ignition, a simple one wire modification. the swtich still works, and i'm still using the factory relay. takes 5 minutes. i'll post a picture of the task if anyone wants to do it themselves.
06-30-2005, 03:38 AM
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Originally Posted by dkrgouki
HA! ok, i figured out the best way to do it. i now have my fog lights coming on when the key is in the ignition, a simple one wire modification. the swtich still works, and i'm still using the factory relay. takes 5 minutes. i'll post a picture of the task if anyone wants to do it themselves.
06-30-2005, 01:59 PM
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thanks guys for all your help. after reading your posts, i figured out what i needed to do.
first, here are some pics of the my 9-led 921 bulbs i'm using for my accent lights. yes, i know they should be 194/168 bulbs, but these do fit! i got these at superbrightleds.com:
ok, now to the fog lights. first pic is of my car with the just the parking lights on. the fog light switch still works:
now, to do this yourself, follow these steps:
1. remove the little kick plate here:
2. if you've installed the fog lights yourself, you should know where the relay is, if you haven't, the relay should be clipped into the integrated relay on the left:
3. once you find the relay, pull it out and you will see a gray wire that goes to the wiring harness of the car. this wire is ran all the way to your front right low beam headlight and this powers the relay. now, clip that gray wire. you are going to tap it to the parking lights which is very easy to find. as you look at the integrated relay, you will see two large connectors on the upper left. the 2nd one is the one you want. wires 15 & 33 are the front two parking light wires and they are both brown in color. i tapped #15 as it was easier to get to. for reference, the wires look like this:
14 32
15 33
16 34
wire 14 is yellow. wire 16 is red. wire 34 is black.
4. now take your gray wire and tap it to one of the brown wires. here is a pic of mine:
first, here are some pics of the my 9-led 921 bulbs i'm using for my accent lights. yes, i know they should be 194/168 bulbs, but these do fit! i got these at superbrightleds.com:
ok, now to the fog lights. first pic is of my car with the just the parking lights on. the fog light switch still works:
now, to do this yourself, follow these steps:
1. remove the little kick plate here:
2. if you've installed the fog lights yourself, you should know where the relay is, if you haven't, the relay should be clipped into the integrated relay on the left:
3. once you find the relay, pull it out and you will see a gray wire that goes to the wiring harness of the car. this wire is ran all the way to your front right low beam headlight and this powers the relay. now, clip that gray wire. you are going to tap it to the parking lights which is very easy to find. as you look at the integrated relay, you will see two large connectors on the upper left. the 2nd one is the one you want. wires 15 & 33 are the front two parking light wires and they are both brown in color. i tapped #15 as it was easier to get to. for reference, the wires look like this:
14 32
15 33
16 34
wire 14 is yellow. wire 16 is red. wire 34 is black.
4. now take your gray wire and tap it to one of the brown wires. here is a pic of mine:
07-12-2005, 08:55 PM
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Originally Posted by 5hift gear
does your stay on even w / o the key being in ? i did it and tap exactly like you said but now i have to turn the fogs off everytime i get out of the car.
if this is not happening for you, then it sounds like maybe you tapped a wire that always has power to it and that's why you have to manually turn them off. i know the parking light wires are very bunched up at the integrated relay, so double check the wire you tapped into and make sure you didn't tap any other wires on accident.
