I'm new to this forum, (and forums in general), can you send a j-peg in a PM? If so I'll do up a detailed drawing with some pictures to boot...
Otherwise, here's a detailed description.
1. Isolate the turn lights from the turn signal controls. (Cut the power and ground wires a few inches from the lights; you will be running new wires to the lights to cover the extra wattage demands that actual fog lights place on the system)
2. Run 14-16 AWG (American Wire Gauge) wires from the lights to a Radio Shack plastic project box placed as close to the underhood fuse box as you can. Secure the box wherever there's room and it looks good, but keep it close to the fuse box. (More on the box size and details later) Don't connect to anything just yet, just route the wires neatly to the box and leave about 6" or so extra at the box.
3. Run an 18 - 22 AWG wire from the hot side of the left high beam and the left low beam headlight wires to the R Shack box, leave an extra 6" on these also. Unplug the headlights and check with a test light while the lights are all on to find the hot wire. (Or you can use a wiring diagram, but I'm trying to write this so no diagrams are needed.)
We're using the left lights because they are closer to the fuse box making the wires easier to run. Also, you only need 20 gauge wire or so because this is only a signal wire with very low amperage.
Important: Put a 5 amp in-line fuse as close to the connection to the lights as possible to protect the headlight system from blowing it's fuse and leaving you without lights if the signal wires were to short for some reason.
4. Run a 14 AWG wire from the under hood fuse block to the plastic box with the rest of the wires, (there should be an open position in the fuse block to install one of those square fuseable link fuses with the clear plastic top, using one of those is the best and cleanest way to do it. Otherwise, tap into the main input and use an inline fuse.)
5. Now that all the wires are in place, its time to decide how to do the relay setup. The control can be setup using some transisters, resisters and a single relay, this is the prefered method but is complex, I'll cover this when I can post some pictures and have more time.
The other way uses two relays as I mentioned above. You will need two standard DPDT automotive relays, they have to have both 87 & 87a output terminals. The other terminals are 30 (input voltage) 85 & 86 (coil trigger). 87 is normal open and 87a is normal closed.
6. Final wiring: Run all the wires into the RS Project box, (needs to be big enough to fit both relays and leave room to fit wires. 3" x 6" x 2" deep works well.) Use black silicone to seal the wire holes to keep water and dirt out.
7. Run the power wire from the main fuse box to terminal 30 on relay A. (use a marker and mark the relays A and B) Connect the high beam wire to terminal 85, connect terminal 86 to ground. Run a jumper from 87a on relay A to terminal 30 on relay B, use 14 AWG for the jumper. Connect low beam wire to terminal 85 on relay B and connect terminal 86 on relay B to ground. Now connect the wires from the fog/corner lights to terminal 87 on relay B.
8. If its all correct terminal 87 on relay A will not be connected to anything, nor will 87a on relay B.
Now put the relays into the box and seal it closed. Put all the fuses in, hope all the fuses have been out till now. If it's all wired right no fuses will blow and the corner lights will come on with the low beams and go off when the high beams are turned on.
Good luck, post if you have any problems or questions.
As far as the j-peg in a PM, I would think so but not sure...
As far as the write up.........THANK YOU, ALOT, ALOT
Looking forward on getting this started
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anyone wire a 95+ combination switch (signal, headlight, fog, wipers) to a pre 95 model? thats what i am trying to do with my car. i see extra wires in one harness plug since 95+ models have timed auto off headlights.
a pinout of the combination switch would be nice but i cant find a 95 and up service manual
Is this all the same with adding a toggle switch to the fogs/corner lights?I'm electrically numb with reading all this but,do I still need to add a relay for a 35w HID H3 on a 95?I just want them to come on and have a separate access switch to off/on my corner lights(no high/low beam etc).What wires do I need to hook up to make this happen?Sorry again electrical work is my only weakness
I don't smoke but....
I do have Carbon Fiber in my lungs!!
On a 95+ I believe you already have a relay to an interior switch on your control stalk. HID's draw more than 35W for a few seconds at startup so I do not know if you should install a battery-draw relay to be safe. If it hasn't been addressed already can anyone confirm this?
Otherwise, the reason a relay is used on a 92-94 is because the cornering lamp circuitry was only designed for 15W current draw. Plus, there was no interior switch to turn them off and on. In 95+ cars you can use an existing switch.
It's a bit of a read but it's all here in this thread. If it helps, the relay system described is very similar to just about every other aftermarket relay installation guide out there with the exception of O.L.T. having kindly noted Lexus-specific wiring notes in his writeup.
Look for picture guides and then refer back to O.L.T.'s notes. It will make more sense.
if someone would dare take on the task of making a write up on a 95+ foglight conversion to our 92-94 cars i would love to see it. i have the wiring schematics for the combo switch stalk and fog lights for a 95+ car.
i already collected a 95+ combo switch (with foglight switch on the signal stalk) and fog lights.
there are added pins in the connector. i cut the pig tails off so i know what to add on to my cars harness. i just need someone to actually do it.
1992 SC300 with 2JZGTE VVTI Swap, 500hp @ 25psi on 93 octane pump gas, Weldon 1100a, FIC 1100cc injectors, R154, BWS366 9179 Turbo,CXracing T4 Heavy Manifold, Precision 46mm wastegate , Godspeed 4" Intercooler, aluminum Radiator, Dual Puller Fans with Aluminum Shroud, Aeromotive FPR, F1 racing stage 3 clutch, DriftMotion AEM EMS V2 heavily modified, AEM 3.5 BAR map, AEM UEGO, AEM boost solenoid, 19 inch TSW Snetterton's, SC400 3.92 diff, 3" downpipe, Megan Racing Exhaust, Megan Racing Coilovers.
Doomlight, I made a thread with pictures detailing a custom interior relay switch for fog lights into a 92-94 SC but your 95+ control stalk diagram is probably different (and ultimately more clean after installation).
The wiring to either 95-96 factory foglights, 97-00 foglights or aftermarket foglights should still be the same concept though. I have no visual writeup on what I did but I kid you not that it is very, very, very similar to creating your own foglight harness for any vehicle. Every writeup online that shows you how to do this will specify a trigger circuit needed to turn them on and usually this is the parking lights because it is just the most convenient place under the hood to splice into.
The only variation from this in O.L.T.'s notes are his addition of a couple of Lexus SC specific wire colors. It's otherwise the same idea.
Again, I don't know how your 95+ stalk wiring goes into the car's harness (and I'm interested) but what I did was run trigger (parking lights) interrupt switch wiring from inside the cabin under the dash to the foglight relay. I placed this near my battery in the same location as my HID resistor wiring.
1993 SC300 5-speed NA | Built R154 | Gixxer_Drew Susp. 600/325 | TT: brakes FR, rims, rear sway, seats | Koyo rad | 4.272 TT Torsen LSD