Need negative switched relay schematic for older Toyota

[pungo]

I've been searching for a schematic to build a wiring harness with relays to upgrade the power getting the the H4/9003 type bulbs for a 96 4runner. Most links I'm finding are dead or missing the pictures. I plan to use 2 relays, one of the lows and one for the highs. I have all the parts, (relays, wire and connectors) I just need a schematic to follow to build it. I find plenty of schematics for positive switched, but not much for negative switched. I hope someone can help by pointing me to a schematic I can use. Maybe there's one right in the forum, but my search did not find any.

 

[jzchen]

Official everything is here, I believe $20 for two days:

https://techinfo.toyota.com/techInf..._US&resource_url=https://techinfo.toyota.com/

I already checked www.helminc.com but they don't have anything for that vintage.

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[pungo]

jzchen, Thanks for the links, but I only need a basic negative switched relay schematic and I'm not even sure if they will even have one, but need to pay $20 to find out. I made one about 10 years ago, I just can't find the diagram.

 

[-Virgil-]

I could have sworn I had the necessary schematic, but I can't find it. See if Dan Stern can cough one up.

 

[jzchen]

(If I understand what you're trying to do)....

If you have the positive switched diagram you just need to swap ground and positive to the input of the coil. (Sorry it's been so long since I was an EE student and never worked as an EE). Hope it makes sense...

So when you turn the switch "on" it grounds the coil.

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[pungo]

jzchen, If I remember correctly, it's not as simple as just swapping ground & positive to the coil inputs.

 

[-Virgil-]

If you have the positive switched diagram you just need to swap ground and positive to the input of the coil.

That advice is adequate for some ground-switching headlamp circuits, but not for Toyotas, the differences on which extend much farther than just "ground-switched".

 

[jzchen]

jzchen, If I remember correctly, it's not as simple as just swapping ground & positive to the coil inputs.

Yes if you want to use the original switch it's going to be beyond me, especially without the wiring diagram from Toyota.

That advice is adequate for some ground-switching headlamp circuits, but not for Toyotas, the differences on which extend much farther than just "ground-switched".

Good point. I was treating his/her car like I'd do my own. I would leave the original circuit as intact as possible and wire it separately, so it can as easily as possible be returned to the original state. But that opens another can of worms with the parking lights not coming on as you're not turning the original handle, and whatever else I can't forsee...

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[-Virgil-]

It's perfectly possible to put headlight relays in a Toyota in a manner so that all the original switches and indicators, etc work fine. The original circuit stays completely intact. It just has to be done correctly.

 

[pungo]

Yes if you want to use the original switch it's going to be beyond me, especially without the wiring diagram from Toyota.Good point. I was treating his/her car like I'd do my own. I would leave the original circuit as intact as possible and wire it separately, so it can as easily as possible be returned to the original state. But that opens another can of worms with the parking lights not coming on as you're not turning the original handle, and whatever else I can't forsee...

Like I said, I did one 10 years ago, I just can find the schematic. It required zero modification to the stock wiring. Simply run battery power to relay harness, disconnect plugs to both headlight bulbs, connect relay harness to light bulbs, take drivers side factory headlight plug and connect it to input of relay harness to trigger the low/hi relays. No can of worms here, everything just worked and could be returned back to stock in a few minutes. Just kills me I can't find the old schematic I used or another one on the internet. Toyota has some different wiring than typical.

 

[430Scuderia]

Like I said, I did one 10 years ago, I just can find the schematic. It required zero modification to the stock wiring. Simply run battery power to relay harness, disconnect plugs to both headlight bulbs, connect relay harness to light bulbs, take drivers side factory headlight plug and connect it to input of relay harness to trigger the low/hi relays. No can of worms here, everything just worked and could be returned back to stock in a few minutes. Just kills me I can't find the old schematic I used or another one on the internet. Toyota has some different wiring than typical.

Maybe post #13 below is what you're looking for:

https://www.yotatech.com/forums/f116/diy-headlight-wiring-harness-upgrade-low-201388/

 

[-Virgil-]

Still "no cigar". The diagram in post #13 of that linked thread is not correct; it's just a schematic for a generic non-toyota ground-switched setup, with a diode added to keep the low beams on with the high beams (which is either a reasonable idea or a very stupid one, depending on if the vehicle uses two 1-filament bulbs or one 2-filament bulb on each side). It's missing a switching diode and it's also missing resistors needed to keep the high beam warning light on the dash working correctly. If I could recall exactly how/where those component parts went in, I'd share here, but I don't.

 

[pungo]

This should do it:

 

[-Virgil-]

YES! That's the one I had in mind, and I was able to use this image to find the same image on one of my drives, along with notes:

R1: resistor 2W 8Ω
D1 & D2: silicon diode, ≥2A with ≥50V max inverse current rating