Bosch Relay Gurus

[chad keene]

I am trying to figure out how to add stock foglights to my 01 Explorer Sport. I have gone through and read multiple threads, and looked at many stock and aftermarket wiring diagrams. I think I have most of it figured out except 1 wire. My plan is to use the original 95-01 stock fog light switch with a Bosch relay to activate the lights. I know I can wire the relay to turn the foglights on at anytime using an ignition power source, but I want to stick with stock. I would like to wire the foglights to come on only with the lowbeams and go off with the highbeams to keep it legal. Which wire would I tap in to to make this happen. Also would there need to be a fuse inline with this wire?



I found this diagram and customized it a bit, to what I hope to do. Pin 85 is the only one I have left to figure out. Any help will be greatly appreciated. I am not sure as to what gauge wire to run also, any ideas. Thanks for reading this thread.



[Broken External Image]:



http://i119.photobucket.com/albums/o158/tazkeene/explorersport/diagram.jpg

 

[Steve McKellop]

The '02 ,'02 and maybe '03 used an isolation relay to kill the fogs on high beam. Here is the stock configuration.

 

[Brad Schultz 2]

It may be that I'm super tired, but I can't follow your diagram. Can you explain the terminals more precisely using this link as a guide, and maybe label the wires? What is the plug you illustrate?



http://media.photobucket.com/image/relay%20wiring/bills985/StarterRelay.jpg



Hi Steve :grin:

 

[chad keene]

My Diagram?



I am using pin 87 to feed the fog lights, Pin 30 for power from the battery, pin 86 to the number 3 slot on the factory fog light switch, and pin 85 I am not sure as of yet how to run it, but I want to run it with the lowbeams only. I'd like to use only relay to complete the job, instead of an extra isolation relay if possible.



From the factory fog light switch the pins are as follows. Pin 1 & 2 not used, pin 3 LB/BLK goes to relay ground 86, pin 4 BLK factory switch ground wire, pin 5 RD/BLK for illumination, pin 6 TN/ORG goes to foglight positive wire for factory switch indicator.



I am following these directions for the factory switch.



(Most aftermarket switch diagrams show the switch on the hot side of the relay coil.

In order for the factory foglamp switch and its indicator lights to work, the factory switch must interrupt the ground side of the relay coil. tan/orange stripe = from relay-switched fog lamp power wire to dash switch's "fog power on" LED , red/black stripe = power from dash illumination circuit to switch's night illumination, blue/blk stripe = wire from ground side of relay coil to switch, blk = single common ground wire from switch and indicator lamps to vehicle chassis ground.



How this setup works:

the relay is a switch that is "turned on" when power is directed to it. It then takes and directs power to the fog lamps. the way the switch is integrated to this is fairly simple. The ground wire from the relay does not go directly to the ground, it goes to the switch. The switch then controls whether or not the relay can have a ground. So when the switch is on (allowing ground) and the parking lamps are on (sending the + side) the relay flips the switch and "POOF" you have light!)

 

[chad keene]

I am trying to do something like this only I don't have factory fogs, so I am only using 1 switch to a factory set of fogs.



http://www.mysporttrac.com/mysporttrac/projects/SecondFogSwitch/SecondFogSwitch.htm



I want to do it this way.



http://www.mysporttrac.com/mysporttrac/projects/SecondFogSwitch/SecondFogSwitch_files/Relay2.jpg



by using the power from the coil side to the headlight lowbeams, but not sure how to wire it to do so.

 

[Todd Z]

[Broken External Image]:

 

[chad keene]

This is how I got it figured out, all except which wire on the light circuit to go to for lowbeams from pin 85, would I go to the highbeam side or lowbeam side to activate with lowbeams only.



<a href="http://s119.photobucket.com/albums/o158/tazkeene/explorersport/?action=view&current=diagram3.jpg" target="_blank"><img src="http://i119.photobucket.com/albums/o158/tazkeene/explorersport/diagram3.jpg" border="0" alt="Photobucket"></a>

 

[chad keene]

Alright I talked to a guy and he recommended I do it like this to protect the headlamp circuit and the relay and wiring as to from a short.



<a href="http://s119.photobucket.com/albums/o158/tazkeene/explorersport/?action=view&current=CorrectWiring.gif" target="_blank"><img src="http://i119.photobucket.com/albums/o158/tazkeene/explorersport/CorrectWiring.gif" border="0" alt="Photobucket"></a>

 

[Brad Schultz 2]

You know what? I just realized I can't read how the fog lights come on! In my mind there is a ground missing. When you indicate "stock low beam", is this the positive trigger and the 18-22 gauge wire is going to ground at the switch.

 

[chad keene]

No pin 85 goes to the lowbeam circuit dark blue/light green wire from the low beam side. The fog light switch turns on/off the foglamps by completing the ground circuit at pin 86. The switch is wired to work so that the foglights only operate with the lowbeams, and go off with the highbeams.



So in other words when the headlights are on, and operating lowbeams you can turn on your fog lights as well.



(How this setup works: the relay is a switch that is "turned on" when power is directed to it. It then takes and directs power to the fog lamps. the way the switch is integrated to this is fairly simple. The ground wire from the relay does not go directly to the ground, it goes to the switch. The switch then controls whether or not the relay can have a ground. So when the switch is on (allowing ground) and the lowbeams are on (sending the + side) the relay flips the switch and you have light!)



Optionally you could wire pin 85 to an ignition on wire to operate the fogs at any time.



Hope this helps.



The factory relay has 5 pins.



Pin 1 is 12 volts from Dimmer switch when in low beam position. This would be pin 85 on a standard relay

Pin 2 is the wire that goes to the factory fog light switch. The switch controls the ground to the relay coil.

When the switch is on it supplies a ground to the relay coil to turn the fog lights on. When off it removes the ground from the coil and the lights turn off. This would be pin 86 on a standard relay

Pin 3 is 12 volt constant and the common contact in the relay. This would be pin 30 on a standard relay

Pin 4 in the normally closed contact. It is not used. This would be pin 87A on a standard relay

Pin 5 is the normally open contact. This would be pin 87 on a standard relay