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View Full Version : Wiring a Defroster switch to hella driving lights



Wiscon_Mark
02-12-2006, 10:01 PM
*Split from "Guess my parts" thread in General*
Story is, we're figuring out the wiring from a factory defrost switch to use for my New Hella driving lights.




or maybe a factory lookin switch to turn those new hellas on with. heh

no, but I am looking for one.

NewGenSTi
02-12-2006, 10:05 PM
I have a factory switch for the rear window defog. dont know if you can rig it to work. but theres one in my parts car

badbasser98
02-12-2006, 10:24 PM
I have a factory switch for the rear window defog. dont know if you can rig it to work. but theres one in my parts car

that will work, just the symbol won't match.

shazapple
02-13-2006, 12:14 AM
and it will turn off every time you switch the car off.

A bumper to put those fancy foglights in?

Wiscon_Mark
02-13-2006, 12:17 AM
and it will turn off every time you switch the car off.

really? Mine doesn't.

no, no bumper, that would be cool as hell though.

badbasser98
02-13-2006, 07:49 PM
and it will turn off every time you switch the car off.


This depends completely how he wires it... if he just wires it straight to a 12v lead it will not shut off with the ignition.

shazapple
02-14-2006, 12:37 AM
and it will turn off every time you switch the car off.


This depends completely how he wires it... if he just wires it straight to a 12v lead it will not shut off with the ignition.

if i hit my rear defrost switch it will turn off in a certain amount of time, or if I turn the car off (when I turn the car back on the rear defrost wont be on)

badbasser98
02-14-2006, 10:26 PM
if i hit my rear defrost switch it will turn off in a certain amount of time, or if I turn the car off (when I turn the car back on the rear defrost wont be on)

i understand that, but there are approx 8 wires leading from the back of the switch that make it behave in the manor. If he just connects a straight 12v lead and a ground wire to the actual switching terminals, the switch will still be hot with the ignition in the off position. I tested this extensively when I put the fogs on my BD.

NewGenSTi
02-15-2006, 01:52 AM
Yeah, there should be 4 wired because there are 2 lights in the switch. one lights up when you press it and the other is illimination for the defrost logo. so there is your 2 feeds(one for the lights, one for whatever its turning on), one ground, and one return to what your switching.

shazapple
02-15-2006, 05:34 PM
pssst mark, heres what I used ;)
http://www.scoobymods.com/forums/showth ... ght+switch (http://www.scoobymods.com/forums/showthread.php?t=5784&highlight=fog+light+switch)

Wiscon_Mark
02-15-2006, 07:14 PM
too bad I'm not using a fog switch :( (but I'll give it a go anyways).

badbasser98
02-15-2006, 08:30 PM
ahh, i was thinking of the cruise switch for all the wires coming out the back. Does your car have cruse.. if not you can use the 12v lead on that plug to power the switch you are putting in and that will shut off with your ignition.

Wiscon_Mark
02-15-2006, 09:28 PM
yeah, I have cruise.

badbasser98
02-15-2006, 09:33 PM
might still be able to get away with splicing into that 12v lead to make the switch you are installing turn off with the ignition.


...and this is a custom setup, I only need 3 wires, so I just have to figure out which is which. (ground, input & output hot).

you are not going to hook up the interior light?

Wiscon_Mark
02-15-2006, 09:34 PM
nah, I'd much rather just use the brights...there's a method to my madness :D

Plays_with_Toys
02-18-2006, 01:04 AM
Hey mark, I just wanted to emphasize that you get a picture of the light output with just headlights and then with the 500's on. The lighting on my car is ridiculous, especially with the yellowstars in it now. Its like the lights aren't even on in anything other than white conditions. I'm looking at the 500 driving lights, and trying to figure out how to mount them to my bumper.

Have you figured it out yet? I'm curious if you can mount the driving lights upside down, because then you could just use the stock holes, use some .5" spacers and run a bar/plate to the front outside of the bumper (since the fogs are too large to fit in the cut outs).

http://img114.imageshack.us/img114/5957/drivinglight4ge.jpg

This is what I will do with mine, as long as you report back if they are too bright for road use/ their light output.

I want to run them with hella yellowstars, so they shouldn't be as bright as normal H3's, but I do intend to use them in city driving. So, let me know how much glare and such they give you.

Wiscon_Mark
02-18-2006, 01:12 AM
sure, pictures and such will come whenever I get a chance to install....I've got mounting semi-figured out; I'm going right in front of the grille...you'll see.

LCO member "Jamal" had a good DIY method for doing it. The parts cost me just around 3 bucks :D

dropdfocus
02-18-2006, 10:32 AM
Coming from a 12v guru, the fog lights being turned on by the defroster switch is rather easy. As said before, you have 4 terminals on the back of the defroster switch (ground, in, out, illumination). Supplied in the Hella kit will be a 30/40 amp relay (likely a Bosch brand relay) that will be used to turn the fog lights on & off. The relay will have 5 terminals, but you won't use the middle terminal since that's for switching another device on as you turn one off. You'll have a ground wire, supplied constant 12v from the battery, constant 12v to the fog lights and then a switched 12v lead to charge the magnetic coil inside the relay (which will come from the defroster switch inside). The switched lead can be tapped from the fuse box from any source that turns off when you remove the key from the ignition (preferably 15 to 20 amp fused). That lead will go to the back of the defroster switch and then come from the switch to the relay. It's as simple as that folks.

As for the defrosters turning off, that is controlled elsewhere outside of the defroster switch, so the dash mounted switch will have nothing to do with that.


P.S. Nice "clothed" pic Jess. Seductive w/o being slutty. :twisted: :roll: :-D

Wiscon_Mark
02-18-2006, 05:43 PM
okay, so I got the switch...it has 6 leads.

Two of them are for each light (one's a dimmer'd light for the logo, one is a orange light indicating the switch is "ON") inside the switch.

At least one is a ground.

Two of them have to be the "send/recieve" signal for the device the switch would be turning on/off.

so I'm guessing one is a ground for the other lights? I dunno...my foglight switch also has 6 leads.

I'll post up a pic when I have access to a camera.

shazapple
02-19-2006, 04:22 AM
Check the scoobymods thread I posted. There isnt much difference between the switches other than the fog switch actually having two positions.

Wiscon_Mark
02-19-2006, 10:52 AM
Lee, the defroster switch also has 2 positions. I think your switch is different. They must be identical...but I don't know if the color of the wires is.

edit:

1 3
--4
--5
2 6

#1- ground for the ON bulb.
#2- ground for the illumination bulb (this ground actually varies depending on the brightness of your dash)
#3- +12 volts when key is on ACC (powers both ON light and relay)
#4- +12 volts for illumination bulb when dash is illuminated
#5- out to relay
#6- same as above (can be used for another relay)

the #6 in my harness is missing, so I guess I can only power one relay. Hopefully its the same setup with the fog switch as it is with the defroster switch (they seem to be the exact same thing).

shazapple
02-19-2006, 12:35 PM
Yeah, Mine came with a wire in #6 but I just taped it up and didnt use it. I suggest taking a 9V battery and a voltmeter to test these out. Its the easiest other than cracking the switch open and figuring it out manually (which Ive done :S)

Wiscon_Mark
02-19-2006, 12:41 PM
well, I'm going to crack the switch open anyways, cause i have to colormatch it ;)

Wiscon_Mark
02-27-2006, 09:00 PM
the guide I posted up there is absolutely true for defroster switches as well :)

shazapple
02-27-2006, 09:19 PM
Yeah, I figure that the plugins are usually the same, but wire colours always change. None of my wire colours matched the guide I posted but the pins were right

Wiscon_Mark
02-27-2006, 09:22 PM
Yeah, I figure that the plugins are usually the same, but wire colours always change. None of my wire colours matched the guide I posted but the pins were right

yep. I will warn you though, the harnesses are NOT the same, they look very very similar, but won't fit for some reason.

shazapple
02-27-2006, 09:25 PM
My defrost, cruise, and fog switches could not be plugged into anything other than their own plugins. They all have a little tab of some sort

shazapple
04-10-2006, 12:54 AM
Update: this is the reason why they wont fit. the small blue and white pieces you see in this picture. They snap out easily enough.

http://img85.imageshack.us/img85/2108/img13694ao.th.jpg (http://img85.imageshack.us/my.php?image=img13694ao.jpg)

On the left is a foglight switch, and the right a rear defrost. The defrost switch in my car doesnt stay on and seems to automatically turn off in 15 minutes. Plus its not a toggle switch, it only has one position.

The switches I listed above were out of a 95 I beleive, and they both have a distinct on/off position

Edit: also, the fog switch has a metal pin in position #6 (see above) to add another relay. The position #6 in the defrost is just plastic and does nothing

jonklein611
06-29-2008, 11:05 PM
See that blue clip and the grey clip in the other switch? If you pop those out, then it will fit in the other and vise versa. Lil plastic insert so the two don't get mixed up.


- Jon

AussieDan
07-01-2008, 12:28 AM
Hey mark I have a spare fog light switch, pm me if you want it.

I have my dual beam setup wired so that the fog lights are on with the low beams and driving lights with the high beams, both controlled by the oem fog switch. You just need 2 relays and 2 diodes to make the circuit.

jonklein611
07-05-2008, 12:58 AM
Hey mark I have a spare fog light switch, pm me if you want it.

I have my dual beam setup wired so that the fog lights are on with the low beams and driving lights with the high beams, both controlled by the oem fog switch. You just need 2 relays and 2 diodes to make the circuit.

any tips on how to wire up the relays?

AussieDan
07-06-2008, 11:11 AM
I can probably cook up a diagram, but basically you wire the input side of each relay from the fog light power wire (white/black) to the low/high beam ground wires (headlights are -ve switched).

You'll need to make a Y from the fog light wire and put a diode in each leg so that the current can't flow between the 2 relays.

With this method your fog lights will come on with the low beams and driving lights with the high beams, as long as the fog light switch is turned on. You will need to perform my semi-independent fog light mod:

https://sl-i.net/FORUM/images/imported/2008/07/foglightwiring-1.jpg (http://photos.phpwerx.net/cars/Legacy/Fog_Light_Mod/800x600/foglightwiring.jpg.html) https://sl-i.net/FORUM/images/imported/2008/07/foglightmod-1.jpg (http://photos.phpwerx.net/cars/Legacy/Fog_Light_Mod/800x600/foglightmod.jpg.html)

Which allows the fog lights to work with both low and high beams.

I did all the wiring for the dual beam mod insider the driver's fender, tapping into the 3 wires you need (fog +ve, low beam gnd, high beam gnd), then run a fused power wire to the battery and a custom harness below the radiator to power the passenger side fog/driving light.

jonklein611
07-08-2008, 03:54 AM
Oh thank you for the wiring diagram! I'm looking for just the foglights part, cause I don't have a set of driving lights.

Heres what I had come up with before I got the diagram from you. FYI im putting in fogs in a BK legacy, using a OEM switch and OEM relay.....

Let me know if you see anything funky with this. THANK YOU SO MUCH!!!!

Transplanted from Legacygt.com


"Looks like this from bottom of relay:

__|_|__
[ 5 2 ]
[ 3 1 ]

Note: 2 and 1, im not sure which is which... because hella does theres for voltage switch, ours change ground, so they might be backwards, eeek.

Pin 2 is Power from the Battery (via 15Amp fuse coming from under dash (Fuse 6, called Fog))
Pin 1 is connected to the Hi Beam Power Supply (via wire from 15A Fuse under hood (Fuse 26, which is powered by the H/L Right Relay))
Pin 3 is connected to your Fog Light Switch (pin 5 or 6 depending on the switch)
Pin 5 is always Power to your Device (Fog lights)


Switch Wiring:

looking from the back of the switch:

1 3
--4
--5
2 6

Pin 1: Goes to Low Beam ground (this connection breaks when you move the lights to Hi Beam, so the fogs will go out) (if you dont like that, then ground the switch to the chassis)

Pin 2: ground for the illumination bulb (one that dims with rest of dash, tie it into another switch on your dash)

Pin 3: Goes to the same point as RELAY Pin 1.

Pin 4: +12 volts for illumination bulb when dash is illuminated (tie into another switch in dash)

Pin 5: Connects to RELAY Pin 3

Pin 6: Connects to RELAY Pin 3

Note: Pin 5 and 6 are interchangeable, some switches have one or the other or both."