How To: Fog Lights ANYTIME
 

Tired of only being able to turn the fog lights on with the low beams? The following modification I performed on my 04 Evo piggybacks the stock fog lamp system without cutting any wires and allows the fog lamps to work independently of the low beams. I have looked at the wiring schematics for 03 - 06 Evos and they function the same and use the same switch, so this mod will work on them all.

This modification requires building a small simple circuit with parts availible at your local RadioShack. The circuit is then installed under the dash with 4 simple wire hookups.

Note: This circuit can be switched on and off repeatedly, however once switched off, there is about a 3 second delay before you can switch it back on as the capacitors discharge.

The Circuit

Parts needed:

1 - MPS2222A or similar small-signal NPN
1 - IRF510 n-channel MOSFET
1 - D1 1N4001 silicon diode
1 - R1 1M 0.25W
1 - R2 4.7M 0.25W
1 - R3 10k 0.25W
1 - R4 330k 0.25W
1 - C1 220nF ceramic disc, polyester or mylar film
1 - C2 100nF ceramic disc, polyester or mylar film
2 - 12v relays
Misc Wiring (red, black, white and green used below)
Project Box
1 - Circuit board
Once you have aquired the parts build the following circit:

http://www.haughs.net/gallery/d/7351-2/schematic.jpg

Note: when wires intersect WITHOUT a dot there is no connection.

There are 4 external connections to this circuit. One connection to ground (white), One to the fog lamp relay's ground (black), one to the fog lamp switch (yellow) and one to a 12v power source(red) (parking lamps, ignition.... this is the power source that will determine when you can switch on your fogs)

(ignore the small red jumper on the left, it was not used)
http://www.haughs.net/gallery/d/7413-2/P2040966.JPG

http://www.haughs.net/gallery/d/7416-2/P2040968.JPG

The extra pin on each relay was cut off as it was not used.

http://www.haughs.net/gallery/d/7407-2/P2040961.JPG


Here is my completed circuit installed into a small project box

http://www.haughs.net/gallery/d/7383-2/DSC00122.JPG

http://www.haughs.net/gallery/d/7398-2/DSC00132.JPG

Installation

1) Find a suitable location under the dash to mount the box

http://www.haughs.net/gallery/d/7401-2/DSC00133.JPG

2) Connect your ground to a chasis ground (white wire from box)

http://www.haughs.net/gallery/d/7395-2/DSC00131.JPG

3) Remove the plastic facia from in front of the speedo to access the back of the fog lamp switch

4) Tap into the top wire of the switch (with the yellow wire from the box) - this wire sees ground when the switch is depressed (this was the correct wire on my 04 Evo. I need confirmation that the same switch is used over all the years)

http://www.haughs.net/gallery/d/7404-2/DSC00134.JPG

5) Connect your 12v source wire (red) to a wire that has 12v when the ignition is on. This will keep you from leaving the fog lamps on when you turn the key off. You could also connect this wire to the parking lamp power wire or the dash lights. This circuit is VERY low current and will not effect any of the existing electronics.

6) Run the wire labeled "to parking lamp relay" (black) into the engine compartment to the fuse box on the drivers side. The relay pointed to in the picture is the fog lamp relay:

http://www.haughs.net/gallery/d/7362-2/DSC00108.JPG

7) To turn the lights on we need to show this relay ground. The contact pointed to is the contact we want our wire connected to. As can be seen in the second picture below here I soldered my wire straight to the relay pin that rests in that contact.

http://www.haughs.net/gallery/d/7368-2/DSC00110.JPG

http://www.haughs.net/gallery/d/7365-2/DSC00109.JPG

However a modified fuse tap can also be used:

http://www.haughs.net/gallery/d/7386-2/DSC00126.JPG

Make sure it is placed in contact with the proper contacts and that it cannot short to any other contact after the relay has been installed (Make sure its firmly in place)

http://www.haughs.net/gallery/d/7389-2/DSC00127.JPG

8) Reinstall the relay:

http://www.haughs.net/gallery/d/7392-2/DSC00128.JPG

http://www.haughs.net/gallery/d/7371-2/DSC00111.JPG

9) Reassemble your dash and pat yourself on the back, its done!

You now have fog lamps that work when YOU want them to work :cool:

http://www.haughs.net/gallery/d/7374-2/DSC00113.JPG

http://www.haughs.net/gallery/d/7377-2/DSC00114.JPG


All pictures located here:

http://www.haughs.net/gallery/v/toys/evo_viii/fog_mod/

...very very very nice write up.

Is it easy to follow? It makes sense to me, but I may have missed something that just seems like a given to me.

My motivation was to not butcher the stock wiring since the fogs are controlled by two ECUs

it would be clean ...and alot easier if the parts you purchased from the shack were preassembled... hint hint... i know of all the parts you're talking about...not sure if the average joe would breeze through an install like this...

you could make some cash putting these together with a backing presassembled...your idea, my suggestion.

Yeah thinking about it, depends on how many are interested, as I have a 6 week old baby girl so I don't have a TON of time :D but if there is enough interest I could probably work something out, but it wouldn't be an overnight thing.

...it's not exactly one of those mods one loses sleep over...but it is a nice mod to have done. I have mine done the other way where fogs come on with parking lights...i'll probably try this out and see how it goes...i like when my buttons work lol

which was my motivation behind this ;)

yeah, i'm kind of electronically challenged.:lol: i don't understand the schematic you posted on how to make this circuit, wish i did! i can follow the rest of the install, just wish there was another way for you to show how to build the circuit.

hmmmm. Maybe I can come up with something. I know not everyone can solder or read schematics. Lemme do some thinking on this as to weather I can come up with something better or make a few of these on the cheap. That is if there is interest.

i would definately be interested in purchasing one of these if you make them for a reasonable price{thumbup}

Me too! Do you have to buy a citcuit board also?

Yeah. I forgot to add that. Thanks. I'll add that now. The layout is what took the longest if I can come up with a decent layout I could probably spit a few of these out pretty quick for not much more than the parts. I'll see what I can come up with tomorrow and what a estimated price would be.

part# 4 board?

I just used the smallest one they had and connected things with solder and wire and such. Its sort of half assed that way but it worked.

Good write and excellent pics. I do think that this might be a little much for non-electrical folks. I have a BSME and took two or three EE classes in college and I don't think I could correctly read the schematic if my life depended on it :updown:. This could be a good side job for you, I am sure a few people here would be interested.{thumbup}