View Full Version : installing relays
05-01-2005, 09:48 PM
is a piece of cake!!!!
They are simple... relays are made to switch a high power current with a low power current.
SPST (single pole single throw) relays
The most common and simplest type of aftermarket relay is a SPST relay and has 4 contacts.
2 are used to complete a "signal" circuit and the other two are used to recieve and deliver the high power current to whatever needs it.
This high current is delivered only when the signal circuit is activated (closed) *click*
You can switch either the + or the - of the "signal" circuit, giving you some wiring flexibility.
ALLWAYS USE A FUSE!! in the high power line coming into the relay...
05-01-2005, 09:55 PM
i'm assuming this applies for headlight relays too?
05-01-2005, 10:03 PM
it applies to all kinds of relays!
Any relay can be used for any application, as long as the power ratings are observed and the switching needs are met - thats where the different types come in.
05-01-2005, 10:21 PM
Lesson 2 Relays dont like to get wet!
I learnt this the hard way.
***THIS IS AN OLD PIC and is an example of a BAD place to put relays. they got wet here!***
the affects of water on a relay
05-02-2005, 09:46 PM
Lesson Three: SPDT realys
this is where relays get interesting :D
Single Pole Double Throw relays in effect deliver high current two different destinations with its switching action.
So, this type of relay is allways delivering power to terminals 87a, untill it gets activated. Then it switches the power over to the other output terminal (87).
With this feature you can make all sorts of switching circuits that mimmic logic! :coocoo:
Heres what I did with mine. In VA, state vehicle law states that foglights must turn off when high beams are turned on... most newer cars do this if they have factory foglights.
SO why not wire mine this way?
I need to somehow make the power to the foglights cut out when the high beams come on. HHHmmmm!!!
And as you may have guessed by now, I simply suplied power to the fog light relay(to terminal 30) with the "always on(87a)" output of the high beam relay. Make sense??
terminals 86 and 85 are the activation circiut
05-02-2005, 10:09 PM
what have we here?
I think I crossed a line with the ghetto bracketry this time... i was hellbent to put them on a hinge so I tried one I found laying around... I think Im going to re-do a more secure bracket.
That one loop of loomed wire you can see next to the relays is the signal and power lines for the high and low beams... those wont get wired until I find new headlight sockets (to avoid butchering the original harness)
Other wise the rest of the wiring is tucked away... I hid one or two more wires on the fender too.
That damn ECU ground is still bothering me... I'll deal with it soon.
PS - yes my braces are wrapped in electrical tape. They are made of metal and at least the drivers side has multiple exposed hot wires at any time. when im working on it...
05-11-2005, 09:13 PM
I found a really good set of connectors at an Advanced Auto Parts near me. Everyone else around had the cheap black plastic ends with small gauge wires coming off of them. They were called car show universal light harnesses or something to that effect. They have the three wires coming off of them for ground/high/low but where they go into the actual harness piece, it is covered in rubber so you cant see where they connect. It is really well built but they are $10 a pair. I bought 2 brand new packs because I had to fully remake my harness upfront so I am going to be switching to a 4high/4low beam system that I think should look really good. And I had mine in the same location and they rusted out like that as well. The worst part is when it rained it would activate the circuit because of the water pooling on the contacts, and made my headlights come on while hooked up to my wigwags in a parking lot for a while. Luckily someone told me so it was all good. I'll get a pic of that wiring harness up soon.
05-11-2005, 09:34 PM
i got some nice relay connectors from napa........i'll get the part number from work for u if u want
05-12-2005, 07:23 AM
also if you have numbers for our headlamp sockets too :D
Powered by vBulletin® Version 4.2.0 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.