North American Turbocoupe Organization



Rewireing Fog Lights
Noname
Guest
#1
I can't find the procedure to rewire fog lights with relays. I tried to get it from the FAQ page but couldnt pull it up. Does anybody have it I would greatly appreciate it.

Thanks James

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88: Densecharger cold air kit w/ K&N, polished upper from Dan E, Gillis Boost valve,4 point roll cage w/ Corbeau seats and G Force 5 point seat belts harness.
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Pete D Offline
Administrator
#2
Rewire Fog Lights by Jeff Korn

The stock fog light wiring system is poorly designed at best, and puts undue electrical loading on the light switch, multifunction switch,
and wiring harness. Putting higher than the stock 55 Watt bulbs in the fog lights will cause even more problems, and lead to light
switch and/or multifunction switch failure. There is a simple solution to this problem – rewire the system to operate the fog lights
through a relay. When a relay is used, the fog lamp circuit only carries about 100 milliamps of current instead to the 10 amps it carries
using the stock 55 W bulbs, or 19 amps when 100 W “off road” bulbs are used. This can greatly extend the life of the light switch and
multifunction switch if you use your fog lights often. A small amount of additional wiring will make the fog lights come on automatically
when you switch to high beams, which will really light up a dark road ahead. I have the fog lights wired this way on all three of my
cars, and really like the light they throw. No wires need to be run through the firewall to do these mods. All the wiring is done near the
front of the car, on the drivers side. DISCLAIMER: In many areas, using your fog lights with high beams is illegal, so this part
mod is “for off road only”. There, I said it, so the DOT can’t come after me.

The basic mod: operating the fog lights through a relay:

Parts needed: A 30 amp fog light relay (about $4 at any parts store), a relay socket or 4 female spade connectors to mate up with the
relay terminals, a fuse holder and a 30 A fuse, several feet of 10 gauge and several feet of 14 gauge automotive wire.

I suggest all connections be soldered, but I suppose some splice connectors would work. The wire color codes listed are for the 87-88,
but MIGHT be the same for 83-86, bit I am not sure.

Locate a place to mount the relay, and mount it. I mounted mine to the top of the core support near the battery using a small metal
“L” bracket. Crawl under the front of the car and locate the harness going to the fog lights. Locate a part of the harness before it
splits off to each fog light, and extract several inches of the Tan / Orange wire from the harness. Cut this wire. Attach a piece of 10
ga wire to the Tan / Orange wire GOING TO THE FOG LIGHTS, and run this wire to one of the two relay contacts. Run another piece of
10 ga wire from the battery terminal of the starter solenoid to a fuse holder, and from the fuse holder to the other relay contact
terminal. The fuse should be located as close to the starter solenoid as possible. TRYING TO GET BY WITHOUT USING A FUSE IS
ASKING FOR TROUBLE! Run a piece of 14 ga wire from the other Tan / Orange wire (coming from the harness going toward the rear of
the car) to one of the relay coil terminals. Run another piece of 14 ga wire from the other relay coil terminal to a good ground. I used
the same screw that mounts the relay to the core support for a ground.

Having the fog lights turn on automatically whenever the high beams are switched on:

Parts needed: the only additional parts needed are two small 1 amp rectifier diodes, 1N4003, 1N4005, 1N4007, etc, available at Radio
shack, and some more 14 gauge wire.

Only a small amount of additional wiring is needed to make the fog lights come on with the high beams. Put one of the diodes in the
Tan / Orange wire going to the relay coil. This diode lets current from the fog light switch flow to the relay, but blocks any current from
the high beams from flowing back to the light switch. Find the Light Green / Black high beam power feed wire going to the driver side
headlight, and tap into it with a length of 14 ga wire. Run this wire to another diode, and run the other side of the diode to the relay
coil terminal that the Tan / Orange fog light wire goes to. This diode will pass current to the relay whenever the high beams are turned
on, thus turning on the fog lights, but will block the fog light current from turning on the high beams. BE SURE TO CONNECT THE
DIODES WITH THE CORRECT POLARITIES, OR NOTHING WILL WORK CORRECTLY!!!
Pete Dunham


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Pete D Offline
Administrator
#3
Might want to down load this diagram to your hard drive
Pete Dunham


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Noname
Guest
#4
Thanks Pete
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goldwing Offline
Senior Member
#5
I'm needing to ask a question or four.
The "Tan/orange" wire leading back to the rear of the car. Is that wire located under the battery? If so, mine appears to be white/orange. I just want to be certain I don't blow something up. Also, do I leave the end loose that leads to the front of the car?

Next, the "Tan/orange" wire that connects to the fog lights. That wire just runs from one fog light to the other ONLY. Plus, That wire is actually on a three wire harness on the drivers side. The passenger side is a two wire harness. Am I tapped into the correct one?

Another, how do I know which plug to connect the leads to on the relay. I know jack about relays.

Last, the diodes. Which way is correct flow path?
And when its connected, let all the electricity flow through the diode or let a piece of wire loop to the other side (forgive me Smile ).

Thanks
T.C:87 5 speed
HOLSET(HE341/HY35W type-D),255 Walbro, No intercooler yet,8lbs boost,Timing @ 9,Low& C.C Plates & SN-95 Bumpsteer Kit, KYB-AGX Struts,Belt driven fan,Custom oil cooler feed,Relocated ECT,Relocated TFI,N/A Hood, showing 178K
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goldwing Offline
Senior Member
#6
Jeff K,
Do you have your eyes turned on ?
I think I have the relay hooked up correct. I went off a Google search on the relay. So fingers crossed.

I'm really more concerned about this part.

"Run a piece of 14 ga wire from the other Tan / Orange wire (coming from the harness going toward the rear of the car) to one of the relay coil terminals.

I just don't see a additional tan/orange wire anywhere in any of the near by harnesses. The only tan/orange wire is from left to right fog light (like a jumper/cross over wire).
I do see a white with orange stripe wire located under the battery tray and is now hooked straight to the relay as instructed. Since its now cut the piece leading to the front of the car is just hanging loose (correct?).

P.S
I'll search this immediately after this post but just incase I don't find it.
Where is the "Multifucntion Switch"?
I'm thinking the turn signal/bright light switch.

THANKS
T.C:87 5 speed
HOLSET(HE341/HY35W type-D),255 Walbro, No intercooler yet,8lbs boost,Timing @ 9,Low& C.C Plates & SN-95 Bumpsteer Kit, KYB-AGX Struts,Belt driven fan,Custom oil cooler feed,Relocated ECT,Relocated TFI,N/A Hood, showing 178K
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Not B Anymore Offline
Administrator
#7
Quote:Originally posted by goldwing:
I'm thinking the turn signal/bright light switch.
Yup
Brian Leavitt
'86 TC 5-Speed -- MS2x w/COP | 83 lb. injectors | T3/T4 50 Trim Stage 3 .63AR | Full 3" Exhaust - No Cat | Motorsport FMIC | Ranger Roller | Ported E6 | Walbro 255HP | Kirban | 20psi | 120-amp 3G | 8.8" 3.55 rear | '03 Cobra Wheels
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vinnietbird Offline
Senior Member
#8
Just buy a fog light wiring kit from Autozone for cheap,. It comes with wiring and relay, super easy, and you can install the spade clips on the factory switch, or wire the new wires and graft them into the factory plug for the factory switch. Costs about $10.00. It even has easy to use instructions with a diagram.
1988 Thunderbird. No details will be given or spoken of.
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goldwing Offline
Senior Member
#9
I'll consider it.
I already have all this stuff wired up. I'm just waitting on the new switch to see if that helps. If not, I may try a new Multifunction switch as well.

I wonder where Jeff is hiding. I seen his name at the top of the board saying he was moderating.

And just for conversation sake. I believe when his instructions were typed up that his White/Orange wire was so filthy that it actually did appear to be tan/orange. (lol)
T.C:87 5 speed
HOLSET(HE341/HY35W type-D),255 Walbro, No intercooler yet,8lbs boost,Timing @ 9,Low& C.C Plates & SN-95 Bumpsteer Kit, KYB-AGX Struts,Belt driven fan,Custom oil cooler feed,Relocated ECT,Relocated TFI,N/A Hood, showing 178K
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Jeff K Offline
Administrator
#10
The procedure I used in the tech articles worked fine for me. Be aware that after 20+ years, wire insulation tends to change color a bit (yellow tends to look light brown, etc). While I could have used a fog light install kit, I prefer to do that kind of stuff myself.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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