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View Full Version : Fog Lights on with Highs Mod for 2000 RS, the right way


IowaRS
01-14-2005, 12:29 AM
I've searched and read many posts on how to make the Fog Lights stay on when you go to High Beams.

I tried the mod from scoobymods this morning that talks about cutting the Yellow/Blue wires and splicing them together.

From scoobymods.com submitted by horatio102

Special thanks to horatio102 for sending in this mod.
................................
3) The connector on the fog light switch should have 5 wires going into
it.
a) Blue/White - power with headlights only. Lights up the switch.
b) Black/White - goes to the relay to turn the lights on.
c) White/Yellow – This is the dashboard illumination wire, to make the switch green when any lights are on.
d) Yellow/Blue1 - This is YB1. It is normally a GND, but when you turn the high beams on it has electricity.
e) Yellow/Blue2 - YB2, all by itself at the bottom of the plug. It
is the GND.

After you verify this using the test light and turning the
ignition/lights, continue.

1) Cut YB1 about 2" from the switch. Wrap the end of the wire going into the harness (as opposed to the side going into the switch) with tape to keep it from shorting out.
2) Cut YB2 about the same length. Strip the ends of the 3 wires. Use a butt connector to crimp them together. It's easiest to twist the switch ends of YB1 and YB2 together, put the butt on, then connect the other end to the YB2 wire in the harness. Wrap with tape.

You now have fog lights that will not turn off when you turn the high beams on. They still won't turn on unless you have the headlights on though.


I must say, after researching, experimenting, and studying the various schematics I could find (the best being from the Mitchell Service Manual CD), that mod isn't the right way to do this. I'll explain later.

When I say "this" I mean I want the fog lights on when the headlights are on and I've turned them on with the factory switch.
This gives me control of the fog lights independent of the High or Low headlights, but still doesn't let the fogs come on unless the headlights are actually on.

Here's the way I see the leads at the fog light switch:
The pinout looking at the back of the switch is:
1 3
- 4
- 5
2 6

Keep in mind these colors may only be for the 2000 Impreza 2.5RS
Position 6 is unused.

(1) Blue/White +12 (or whatever battery voltage is) with headlights ON only. Also puts +12 to the Light in the switch that shows the fogs are on.

(3) Black/White Goes to the negative side of the coil in the relay that activates the fog light relay switch

(4) White/Yellow This is the dashboard illumination wire, to make the switch green when any lights are on. This is +12 or battery voltage when the parking lights or parking lights and headlights are on.

(2) Yellow/Blue *This is where the above quoted post is incorrect* This is actually the other side of the dashboard illumination. The way the dashboard lights dim in this car is that one side of the lights get battery voltage (Pin 4, above) and this wire varies from 0 to 12 volts. If this wire is 0 there is 12 volts of potential across the bulbs and they light up bright. If this wire is 12 then there is hardly any potential across the bulbs and they are dim. I discovered this when I tapped into the lights to install my boost, EGT, and FPR gauges.

(5) Yellow/Blue *Above quoted post is also incorrect on this one*
This is a switched GND. This wire actually T's into both low beam headlights GND side and the HI-LO switch stalk on the steering column. When the switch is in the LOW BEAM position this is GND. When the switch is in the HIGH BEAM position this wire is actually OPEN. I believe the voltage that is seen when this wire is OPEN is actually that induced by the low beam filament by the energy going through the high beam filament.


The key here is that the quoted post instructs you to disconnect wire 5 (Yel/Blue) and connect it to wire 2 (Yel/Blue). Unfortunately this only works when the dash lights are bright, because at that time wire 2 is near ground potential. (I was messing with my dimmer switch and heard the relay "chattering" because it wasn't grounded well enough).

To do this right you don't want to mess with either of the wires that go to the illumination light. Those wires are 2 (Yel/Blue) and 4 (White/Yel).


All you have to do to make the Fogs independent of the HI/LO, but still only come on when the headlights are on is to:

-Cut wire 5 (Yel/Blue) near the switch, but leave enough wire to connect to another wire.
-Insulate the wire that isn't connected to the switch anymore with tape.
-Connect wire 5, that's still attached to the switch, to a permanent ground somewhere (wire 6 (BLK) on the cruise control switch appears to be grounded to the strut tower,splicing into that should do it).
-Test to see that it's working as desired.
DONE!!!!

Standard disclaimer, you do this at your own risk in every way.

ENJOY!!

ultrasonic
01-14-2005, 01:55 PM
Thanks for working this out. I discovered the same "chattering relay" problem when I did the original mod. I had not figured out a solution so I just leave the dash illumination on full bright. It appears as though you have devised a simple and elegant solution to a mod that must have been done incorrectly hundreds of times. Next time I'm under the dash I'll try your version.

brunetmj
01-14-2005, 03:17 PM
I think it would be great if someone could do some nice diagrams of all the variations on this. Would make a great sticky.

Stock Fog lights variations.

After market Fogs- lights off low beam and independent switch
driving light wiring - independently and off high beam

Below is a link for using the same after market lights as a fog lights
and then using them as driving lights (after reaiming them)

http://forums.nasioc.com/forums/showthread.php?t=697162

gharari
01-28-2005, 02:04 PM
Just yesterday I saw a pinout diagram for the fog light switch. I think it was a pdf file or jpg linked in one of the forumes. Now I can't find it. Anyone seen this and can point me to it?

AcquaCow
01-29-2005, 11:07 AM
Score!

I may give this a go today once it warms up to more than 20deg F. =P

Thanks for the update at scoobymods too,

-- Dave

tooocool49723
01-30-2005, 03:35 PM
a mod should link to this thread in the FAQ (hint, hint).

Great writeup, If you want, I could try to get some pics of the back of the switches?

IowaRS
01-31-2005, 11:40 PM
Here we go, fog switch on the left, cruise on the right:
http://www.imagevenue.com/loc153/th_6b3_DSC00432.JPG (http://www.imagevenue.com/img.php?loc=loc153&image=6b3_DSC00432.JPG)

Here's the finished soldering of the ground wire:
http://www.imagevenue.com/loc107/th_a20_DSC00437.JPG (http://www.imagevenue.com/img.php?loc=loc107&image=a20_DSC00437.JPG)

tooocool49723
02-22-2005, 05:53 PM
Ok, now, given what we know, how could we do a fogs on with parking lights mod? (i've been in this situation before where there is just SO much glare from the lows that you wish they weren't there. I actually drove ~10 blocks with my lights off because you could see better using the streetlights than your low beams(with parking lights on for safety of course).

I've been trying to do this, but it's coming up with a very wierd result... I've connected wire 4 with 1, but this results in the headlights being on in the parking light position, and one being much dimmer than the other. I have this connection switched, and the part that really messes with my head is that when I turn the switch ON, connecting the wires, both lights are the same intensity (bright). If I disconnect the switch entirely (sever the connection) it works like stock. I'm starting to think the LED in the switch is the culprit.

That's beside the point. What would be the proper wires to use to get the fogs on with the parking lights?

Also, with the fogs on with highs mod, I still dont think we've got it 100%. Try turning on your highs, then turning on your fogs. Mine dont come on. BUT if I turn the fogs on in the low position, then flip on the highs my fogs stay on. Just some food for thought.

tooocool49723
02-22-2005, 08:59 PM
update: i've taken out all my splices, except for the highs on with fogs as that didn't do anything, and it still does it? I'm starting to think that when I used the vamp tap on wire 1 that mabye I cut into the wires deep enough to cause resistance? I've also noticed that the fog light switch yellow light is dim, and is bright when I connect those 2 wires (4&1).

dum dee dum dum dum... I keep leaning twords re-wiring everything, but dont want to get into the middle of that in the middle of feb. (it's 21 degrees outside right now).

AcquaCow
02-22-2005, 10:02 PM
When I do the mod, I'm going to do it with a 3-say switch added to the existing switch. This way with the 3-way in one position, the fogs operate like stock (great for inspection time) another way, they'll work with highs, and another way they will just be on (possibly with running lights).

-- Dave

brunetmj
02-23-2005, 12:52 AM
I think any addition for fog light modifciations is great. I know we all have different needs. However it is diffcult for me to understand why anyone would want to have their fog lights on with the high beams. If i am in fog or in snow the last thing i would want is high beams.They cause way to much glare under those conditions.

tooocool49723
02-23-2005, 12:56 AM
Yes, but when driving down the highway on a perfectly clear night, those fogs just give you a little extra light off to the immediate sides. Good for deer spotting.