1st off... im a very technical person with years experience in wiring and electronics... but one thing that always gets me is how to properly wire a relay...

Hate to sound like an asshole, but are you sure? That diagram you posted is pretty straight forward.

WHAT type of relay is needed... pins.... etc?

http://www.radioshack.com/product/index.jsp?productId=2062477
http://www.radioshack.com/product/index.jsp?productId=2501527


And to freshen up on your relay knowledge:

SPDT Relay : (Single Pole Double Throw Relay) an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), 1 normally closed terminal (87a), and one normally open terminal (87).

When the coil of the relay is at rest (not energized), the common terminal (30) and the normally closed terminal (87a) have continuity. When the coil is energized, the common terminal (30) and the normally open terminal (87) have continuity.

The coil is an electromagnet that causes the arm that is always connected to the common (30) to pivot when energized whereby contact is broken from the normally closed terminal (87a) and made with the normally open terminal (87).

SPST Relay : (Single Pole Single Throw Relay) an electromagnetic switch, consist of a coil (terminals 85 & 86), 1 common terminal (30), and one normally open terminal (87). It does not have a normally closed terminal like the SPDT relay.

When energizing the coil of a relay, polarity of the coil does not matter unless there is a diode across the coil. If a diode is not present, you may attach positive voltage to either terminal of the coil and negative voltage to the other, otherwise you must connect positive to the side of the coil that the cathode side (side with stripe) of the diode is connected and negative to side of the coil that the anode side of the diode is connected.

Single Pole Double Throw (SPDT) Relay Single Pole Double Throw (SPDT) Relay - Coil NOT Energized Single Pole Double Throw (SPDT) Relay - Coil Energized
Diodes are most often used across the coil to provide a path for current when the current path to the relay is interrupted (i.e. switched off, coil no longer energized). This allows the coil field to collapse without the voltage spike that would otherwise be generated. The diode protects switch or relay contacts and other circuits that may be sensitive to voltage spikes. (JimR, contributor, install bay member)

Why do I want to use a relay and do I really need to? Anytime you want to switch a device which draws more current than is provided by an output of a switch or component you'll need to use a relay. The coil of an SPDT relay that we most commonly use draws very little current (less than 200 milliamps) and the amount of current that you can pass through a relay's common, normally closed, and normally open contacts will handle up to 30 or 40 amps. This allows you to switch devices such as headlights, parking lights, horns, etc., with low amperage outputs such as those found on keyless entry and alarm systems, and other components. In some cases you may need to switch multiple things at the same time using one output. A single output connected to multiple relays will allow you to open continuity and/or close continuity simultaneously on multiple wires.

 

I have a relay that I want to use from an ebay harness that didn't work. So I salvaged a few pieces and I'm going to make my own harness. How do I differentiate the 4 different parts of the relay to wire them correctly?

Thanks

 

There is a diagram on the relay itself similar to in the pic in post 1.

On this diagram will have numbers for each side of the relay...

Look at the pins, these numbers will be also written above each pin so you know which is which.

 

Im sure you could do it with a multimeter.

As you can see in the pic there is a switched side and a constant side.

You can see 86 and 35. There should be continuity between these 2 pins. Just select your multimeter to Ohms and check the pin combinations for continuity.

Once you have found these 2 pins, you will know the other 2 have to be the switched side.

Once you put 12v through 86 and 35, the switched side will then be active.

Thats how i would imagine you could do it.

Im sure you could figure it out by looking at the internals. I personally would just spend the couple of dollars for a good known working relay without the hassle...

There may be simpler ways... thats just how i would tackle it. Some wiring gurus may know more than me.

 

Good post. ^ I think you properly explained how a relay works. As most of my relays DO NOT have a diagram on them. and THAT is my main problem... I can always find the coil side, but the rest no. Thanks for the post!


and

WTF is up wit morons on this forum? Yes I do wiring, soldering, fixing electronics for a Internet Service Provider but LIKE I SAID.. relays are my black area. I have never had to work wit them and yes I never went to school for it, yet... but Thanks for the intelligent 75% remainder of your reply. If I wanted you to judge me, I wudda made a post with that title.

 

Relay are hard to understand but once you get it. its like a bike you'll never forget.

Usually when I wire the relay's 85 (-),negative,ground,<samething and 86 (+). One of those need to be the trigger/switch. So if you have ground 85 then the trigger would be 86 with something (+) clicking it on and off, vice versa. Now 30 would be used for the thing you want to control on and off. Which in your case is the solenoid.(For the record a solenoid is a relay the handle bigger amperage.) Then the relay 87 I would put 12v. 87a(A is for at rest) need nothing.

basically when the relay is at rest, the 30(nitrous solenoid) is inactive(resting). When you get your trigger from your 85 or 86 the switch from 30 will click over to 87(wired 12v constant) giving the 30(nitrous solenoid) 12v that it needs.

Questions for you why are you using switched 12v. And what the ECU deal in this. I would avoid the ecu wiring, because it is very sensitive to changes is resistance. If you still need to use the ecu wire is that output wire (-).

You can get a relay in Best Buy for $7 but their in the the install bay. I don't know how to determine an good or a bad relay since their cheaply($) made. Bosch I heard is the best. Retail is $7-$12 cost is $1-$2.

quick over view.
85 is from you ECU if negative
86 12V
30 your solenoid
87a nothing
87 12v

If the ECU wire is constant ground, then Use a switch on the 86's 12v. A basic switch. If your ECU wire goes on and off then the 86 12v could be constant.

If the wires on 85 and 86 are both constant the relay would alway be active on 87 never at rest. This is another way to wire also, to confusing for basics tho.

 

Thanks I got it working now... I have a ZEX dry and I wanted my KPro to see the proper time to spray, adjust fuel and ignition acordingly, then power my zex box via a relay... the ZEX will get the 12V it needs from Kpro, then see 100%throttle and fire the nitrous....

I have my relay working, its sending the 12V to my ZEX + line now, I just need to fully test and see if the ZEX continues and fires at WOT.

THANKS for the intelligent responses guys.

 

the diagram of a relay are here http://www.the12volt.com/relays/relays.asp
the first pic is the view form the plug that has the wires. Its a common setup

 

kinda late , but i always describe relays as a magnetic switch thats actuated by power , put simply.

in that diagram you posted , #86 , 12v is ignition power from key , #85 , wire going to ecu is ground , which is how the ecu turns the relay on and off , by grounding it. #30 is the INPUT per say of the relay , and #87 is the OUTPUT put simply , the wire which will go live once relay is turned on.