How to use relays for headlights?

Post by **mlowe76** » Fri May 30, 2003 10:18 pm

Does any one have a wiring diagram showing how to incorporate relays into my headlight set up?

I wish to power my low beam and high beam via relays as my old wiring is just too weak.

Thanks
matt

Post by **ozy1** » Sat May 31, 2003 8:03 am

mate, its not too difficult at all. i looked at doing mine over 3 months ago, went out bought the relays, and left it at that. I kept putting it off, until one day, i took a sickday and did all the work.
I used 1. 4 of 40amp relays,
2. i fuse block with 4 fuse provisions
3. Purchased 10m of 25 amp wire (way too much, but i still have it for many jobs)
4. packets or female spade connecters,
5. 2 heavy duty heatlamp plugs
and a range of other stuff.
I am no Electrician, it was a back yard jobbie, but they are working brillantly. Im using factory sealed beam at the moment and it has made a minor difference. The bit difference will be when i get my new 90/130's bulbs. It is quite simple to do, you will find there are 3 wires on your headlight plug, you have a low beam, a high beam and a negative.

-Take the low beam wire and the high beam wire and connect to the switching terminal of the appropriate relatys clearly marking which relay is which
-Take some 25amp wire, and connect power the your relay through the fuse block.
-connect the headlamp plugs to the accesory out plug on your relay, making sure to connect in the right order. the plugs are labled.
- connect your negative straight back the the original on your factory wiring harness.

I hope this helps you as i did not use a diagram, but if you were to ask me nicely, i could attempt to draw you one up.

Shawn

Post by **purefmx** » Sat May 31, 2003 11:14 am

see attached image or link
Cheers, Wayne
(I tend to always keep a copy handy)
http://www.humanspeakers.com/audi/headlight-circuit.htm

Post by **mlowe76** » Sat May 31, 2003 12:23 pm

purefmx - thats sorta not what I wanted but thanks

I needed more what Ozy1 suggested:)

The weird part is I cant quite figure out how to run them the same as stock.

I'm missing something in my setup, If i unplug the normal lights and run the low and hi and ground throu relays the lights work fine, however the highbeam indicator doesnt work.

So I gather my setup is somehow wrong.

Ozy1 - could you try to draw me a piccy So i can see if its what I've already tried? I'm probably close but just slightly wrong

I wish I could get it working my current wiring is so weak I dunno if my head lights are on or not half the time

Thanks
matt

Post by **RUFF** » Sat May 31, 2003 1:40 pm

Matt i think wayne actually has it right but i have now re-done his picture but in the way that ozy 1 has discribed i beleive.

Post by **MKPatrolGuy** » Sat May 31, 2003 1:51 pm

RUFF wrote:Matt i think wayne actually has it right but i have now re-done his picture but in the way that ozy 1 has discribed i beleive.

Only thing is the earth wire should connect back the the negative wire in the original headlight harness. The headlights in a lot of cars are Negatively switched and as I found out if you earth the relays to the body the lights don't switch on properly.

Post by **RUFF** » Sat May 31, 2003 2:11 pm

The earth on the relay should have nothing to do with it as its only an earth for the relay to switch over not an earth to the light.

I could be wrong though.

Post by **cplux** » Sat May 31, 2003 2:36 pm

some healdights are factory wired different to others, my mechanic mate reckons toyotas are the worst they are somehow wired weired in switch or something.
anyways when i did my headlight relays about 6 yrs ago i found that i had to add a dummy load (10w resistors) in the original wiring loom to make the high beam light work properly, the high beams worked fine however without doing this.

Post by **MKPatrolGuy** » Sat May 31, 2003 3:09 pm

RUFF wrote:The earth on the relay should have nothing to do with it as its only an earth for the relay to switch over not an earth to the light.

I could be wrong though.

In my patrol I originally wired it up how you have it drawn and I could not get the High and Low beams to work right. Either one or the other filament would light up or both on low beam and none on high etc etc, but as soon as I connected the relay earth to the headlight harness not the body everything worked right. I was told it is because the my headlights are negatively switched, Dunno exactly how it works.

Post by **ozy1** » Sat May 31, 2003 3:23 pm

I will work on the drawing 2nite and get it scanned 2morrow for ya.

I have heard with the toyotas especially the high beam indicator may not work, as i have seen in my mates 4runna,

the pic should be posted by 2morrow night.

Shawn

Post by **ozy1** » Sat May 31, 2003 4:24 pm

here is the diagram for yourself and anyone else

Website · Post by **murcod** » Sat May 31, 2003 4:32 pm

Apparently some vehicles are a PITA to wire as has already been said. One way that will always work is to simply wire the relay coil to the two wires that are powering the relevant globe your putting the relay in for.

I don't know how this will work for the vehicles mentioned that were having problems with the high beam indicator on the dash.

Post by **mlowe76** » Sat May 31, 2003 7:48 pm

Ozy1 thanks for that

Thats what I have tried - I THINK.

but I have the same problem as MKpatrol suggested - damn.

I guess I just run the ground from the relays to the headlights ground?

Where does the ground from the standard wiring go? Headlight still or the body?

MkPatrolguy - what did you do with yours?

Thanks
matt

Post by **ozy1** » Sun Jun 01, 2003 7:04 am

I connected my cround exactly the way the diagram shows, and i have no problems, thats was a last minute decision i made when wiring them up,

I am unsure there the standard ground goes, but id say if you have the fully detailed service manual like i had for my old MQ it should have a complete wiring diagram for your 4by,

Good luck

Shawn

Post by **Bush65** » Sun Jun 01, 2003 9:35 am

Good info here http://lighting.mbz.org/tech/relays/relays.html

Also covers the earth switching issues from Japanese cars.

Post by **MKPatrolGuy** » Sun Jun 01, 2003 11:57 am

This is the only thing I did differently to Ozy1

Post by **DAZZ** » Mon Jun 02, 2003 8:54 pm

Some Cruisers and Hiluxs are wired strange in that they are earthed switched and use a voltage differance on either side of the high beam indicator lamp to change weather it is on or off. When fitting a dual headlamp relay a wire needs to be run from the high beam output of the relay to the high beam indicator and the other side to ground. The back feed from the headlight filiments will keep the indicator on.

This is probably clear as mud.

Post by **mlowe76** » Mon Jun 02, 2003 10:30 pm

My brain hurts

I will put up with dull head lights for the time being:)

Thanks for all the info I'll give it a shot next weekend

Thanks
matt

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How to use relays for headlights?

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