How To Wire Up A Relay...

[koro]

Hi, after loads of googling i`m getting more confused...

 

I intend placing a live switched feed into a relay and out to a pair of dipped headlights..

 

Which kind of relay would I need, and how would I wire it up?

 

There would be 2 inline 10amp fuses to go in as well, do they go in before the relay or after?

 

The confusing ( more so) bit, is that am I right in thinking a relay has another permanent live feed going into it as well as the switched live feed?

 

Many Thanks

[bj2004]

what about main beam does this work or not ?

[koro]

what about main beam does this work or not ?

 

Yes, main beam works ok.

[M0GWR]

Hi

Hope this helps, you will need a normal 4 pin relay for this, i would prob use a 20amp. I have done a very bad paint image to show you how to connect the relay. You do need 2 lives to the relay but i would have the trigger live from the ignition so you do not forget and leave the lights on.

[koro]

Thanks for that, would I ask for a 20amp, 4 pin relay to the parts guy?

 

I have a live feed from the switch.

 

Would the second live come from the baterry.

 

I dont understand by what you say the trigger live.

 

Would the 20amp relay be ok for both dipped headlights

 

How do you know which is wich on the 4 pin relay

 

Sorry for all the questions....your drawing was masterfull...

 

oh with the switch being a live feed, would that not make it as 3 live feeds going into the relay

Edited March 14, 2010 by koro

[mk2vr6]

the switched live feed your using is from where?

[M0GWR]

Cheep relay here and it shows a pic on top of the connections, the trigger is what ever feed you use, ignition, dipped head lights etc

 

 

 

http://cgi.ebay.co.uk/5-Pin-automotive-typ...68#ht_678wt_939

[koro]

the switched live feed your using is from where?

 

Hi, P4 on the MFU, using pin 8...when I turn on the lights I get 12v from it. So was thinking that would be a switched live into the relay...have I got that wrong.

[koro]

Cheep relay here and it shows a pic on top of the connections, the trigger is what ever feed you use, ignition, dipped head lights etc

 

 

 

http://cgi.ebay.co.uk/5-Pin-automotive-typ...68#ht_678wt_939

 

 

Cheers,,, looking at your picture, if I use the live feed from the switch, would i disregard one of the other feeds in your diagram?

[koro]

[untitled.bmp

 

 

Hi, hope this works, Got to say to anyone looking, this is a humble guess to how I would wire up a 4 pin relay....

 

If you can make any sense out of it, could you guys that know, have a look.....

[M0GWR]

[untitled.bmp

 

 

Hi, hope this works, Got to say to anyone looking, this is a humble guess to how I would wire up a 4 pin relay....

 

If you can make any sense out of it, could you guys that know, have a look.....

 

 

 

Looks good to me

[koro]

[untitled.bmp

 

 

Hi, hope this works, Got to say to anyone looking, this is a humble guess to how I would wire up a 4 pin relay....

 

If you can make any sense out of it, could you guys that know, have a look.....

 

 

 

Looks good to me

 

 

As in, yep thats the right way to wire one up,or good effort at the crap drawing, lol

[M0GWR]

yes thats the way to wire it up

[koro]

yes thats the way to wire it up

 

 

Many thanks for looking, if i get a normal 4 pin relay 20 amp, will it have a diagram on the top, so I know which pin is which?

 

Is "normal" the correct terminology for a relay, the parts guy I go to, aint the most helpfull...

[chrispb123456]

yes thats the way to wire it up

 

 

Many thanks for looking, if i get a normal 4 pin relay 20 amp, will it have a diagram on the top, so I know which pin is which?

 

Is "normal" the correct terminology for a relay, the parts guy I go to, aint the most helpfull...

Hi just being nosey here, are you trying to repair a fault on your headlights or add extra lights?

Would just like to say be carefull when wiring into lights on a vehicle with (bulb failure relay) thats the little amber symbol of a light bulb that comes on when you first switch on ignition and goes off when you press footbrake,

[mk2vr6]

you said the yellow wire in an earlier post to feed the dipped lights? are you sure on that? cos my diags show the dipped feed to be either a yellow/black or a white wire both fed from different fuses! I would go back and check all the fuses to be on the safe side before you start cutting into the loom!

[koro]

Hi just being nosey here, are you trying to repair a fault on your headlights or add extra lights?

Would just like to say be carefull when wiring into lights on a vehicle with (bulb failure relay) thats the little amber symbol of a light bulb that comes on when you first switch on ignition and goes off when you press footbrake,

 

Hi, on my VW Sharan "w" reg, 2000 1.9tdi, I dont get " the little amber symbol of a light bulb that comes on when you first switch on ignition and goes off when you press footbrake"

 

The dipped headlights dont work, no voltage to the bulb holder, replaced bulbs, fuses ok, switch ok...

 

I intend keeping the Sharan as as a workhorse until it dies... So as an inexpensive fix, though probably not the correct way of going about it. I intend to wire in a new relay and feed he dipped lights direct, throug the switch and suitably fused.

[bj2004]

Relay ive just bought 2 of theese very cheap work well and have nice diagram on cover

hth

M0 NDU

Edited March 15, 2010 by bj2004

[koro]

you said the yellow wire in an earlier post to feed the dipped lights? are you sure on that? cos my diags show the dipped feed to be either a yellow/black or a white wire both fed from different fuses! I would go back and check all the fuses to be on the safe side before you start cutting into the loom!

 

 

Hi, thanks for asking...

 

Just checked again, the dipped light bulbholder has a brown and a yellow. It was the yellow that I was going to conect to from the relay. On P4 on the MFU, there is a black /white feeding into pin 8 is the live feed, that I was going to use a switched live feed into the relay.(It I think is fed from the dashboard switch, voltage reading when I turn the switch on and off).

 

Thanks

[koro]

Relay ive just bought 2 of theese very cheap work well and have nice diagram on cover

hth

M0 NDU

 

 

Thanks for that,,, I got to get this sorted today, having the Mrs walking in front of the Sharan with a lamp at night, is causing a strain on our marriage....into Halfrauds..

[koro]

An update...

 

Into Halfords, bought a 20amp 4 pin relay, wired it all up as in my diagram...surprise, surprise it works..

 

The missing dipped headlights are back on again, sods law when I use them in earnest in the dark, something may go wrong....but fingers crossed

 

Thanks to everybody that contributed, I certainly would not have been able to fix them without you.

 

( must add, I havn`t a clue as to what the original problem was, but this will do for me)

 

Cheers

Koro

[dave030445]

hi hope you don't mind a silly question but what does a relay do why cant you just take the feed from the switch straight to the the head light so when you turn the switch on it power goes to the head light like house wiring you have a fed on one side of the switch when you turn the switch on power goes to the other side

cheers dave

[big_kev]

hi hope you don't mind a silly question but what does a relay do why cant you just take the feed from the switch straight to the the head light so when you turn the switch on it power goes to the head light like house wiring you have a fed on one side of the switch when you turn the switch on power goes to the other side

cheers dave

 

In general a relay is just a big switch that can handle a lot more current than a little switch.

 

The little switch turns the relay on and that then provides power to the head light.

 

If you fed the headlight direct from the switch it would burn out the contacts inside the switch.

 

Vehicle electrics are low voltage and hence high current.

House electrics are higher voltage and hence lower current.

 

Power ( watts ) = Voltage ( volts ) x Current ( Amp.s)

 

60 watt bulb using 12volt supply draws 5 amps.

 

60 watt bulb using 240volt supply draws 0.25 amps.

 

Hence you can use smaller switches for house mains electrics without needing a relay.

Edited March 15, 2010 by big_kev

[chrispb123456]

hi hope you don't mind a silly question but what does a relay do why cant you just take the feed from the switch straight to the the head light so when you turn the switch on it power goes to the head light like house wiring you have a fed on one side of the switch when you turn the switch on power goes to the other side

cheers dave

Hi A relay is simply an electrical switch they are used on things like headlights heated windows electric windows etc, anything really that draws a heavy load, the normal switches used on cars today are not designed to take the full current and as most relays are in a central fuse box it reduces the size and amount of wiring needed.

Relays can also be controlled by ECU's modules and timers for safety related items.

[koro]

Hi, not a silly question at all, I thought the same.....loads of surfing and asking questions, the 2 posts before mine say it all.......