Remote turn-on relay (relay diagram)

I went banannas trying to find this diagram, so I might as well link to it...

This is the proper (and tested!) installation for a remote-switched relay installation. You'd use this in an application like, say, when you want to use a relay to turn on some cathode bars, using an existing power source as the trigger. In my case, I used my car's (a 2006 MINI Cooper S) existing foot well light power to trigger the cathodes, but you could just as easily use a switched 12v. power source. In this installation, the "triggering" power source is wired to pole #86 (labeled "connect to remote turn-on lead" here). All the rest should be self-explainatory.

ULTRA BUMP!

To be honest I think this pic deserves a spot in the wiring diagrams sticky thread!
The most simple and useful way to use a relay right here, and it's exactly what I needed.

Figured since I needed it I'd bump it up incase anyone else is having trouble fidning how to use a relay for a remote turn on!

I am wanting to do this but also control the lights with a switch. How exactly to I wire that around? any help is greatly appreciated.

Run a wire from a 12v source to 86 . Split this wire somewhere before the relay and install the switch you want to use on this wire . Connect 30 to another 12v source, the one you'll be using to power the lights with . Ground 85 . Connect 87 to the positive wire of your lighting, and ground the negative wire of your lighting .

So run 86 to the battery (fused) and run 30 to my dome light?

First of all... A dome light? Why are you using a relay to power a dome light Is it a HID dome unit or something? (heh)... Relays are only really needed when you're switching on large amperage devices like driving lamps which draw more juice than is good to have flowing through a switch (which your finger is touching let's not forget), or when you MUST have binary "on/off" voltage like with cathodes when the triggering voltage is not constant (like with dimming cabin lighting). Low-amperage devices like LEDs and cathodes running off a switch can just be directly wired (with appropriate fusing) without needing a relay.

However, if you really must use a relay, the listed terminal functions of a Bosch relay are as follows:



* 30 is the common or input voltage to be switched. There should be a fuse on this wire - use whatever you need to to power your accessory. Things like driving lights can use much larger fuses - 20A or more. Check your accessory's documentation for details on the unit's expected draw. Fuses should ALWAYS be within 12" of the battery.

* 87a is the normally closed connection. This terminal is hot when the relay isn't energized, it is unpowered the relay is energized. (This terminal is generally not used, unless you want an LED or bulb to light whrn the relay is switched OFF)

* 87 is the normally open connection. Powered only when the relay is energized. This is the connection that goes live when the relay is switched on.

* 86 is connected to the positive 12V of the triggering voltage.

* 85 is connected to the ground of the triggering voltage.

So what Cooper says is correct HOWEVER, I'd still run a fuse on the wire between the battery and terminal 86 if you can (a 3A will do), especially if the length of that wire is more than about 10". If you get a surge though that unfused wire, it can exceed the rating of that gauge of wire and start a fire. Since you'll have a switch on this wire (in the cabin) it will almost certainly be longer than 10" so I'd fuse it for safety - you'll feel like a complete ass if you flip the switch and something starts flaming.

So, both 86 AND 30 will be connected to the positive terminal of the battery. The wire going to terminal 86 will have a switch on it, which will interupt the "triggering voltage" when switched off.

The accessory's positive wire is hooked to terminal 87 (not 30).

The relay is grounded to terminal 85.

The accessory's negative wire is grounded separately (any good ground connection).

Terminal 87A is NOT USED.

So what happens is when the switch is flipped, the trigger voltage going to terminal 86 makes a connection, hooking 30 together with 87. Current flows through the relay and into the accessory, then into the ground hooked to the assessory.

Clear as mud? It sounds confusing, but if you look, the terminals are like a cross - 30 and 87 are across form one-another and they connect when the trigger voltage links them. Likewise 86 and 85 are across from each other, and this is where the trigger voltage goes in and out. When no trigger voltage is present (because you interrupt it with a switch) then 30 and 87 disconnect and your accessory gets no juice. Get it?

What I am doing is running flex strips under my dash and in the back seat. I want them to come on when the door opens as well as controlled by a switch so I can have them on whie the doors are closed.

I don't think you'll need a relay for a few flex strips... the amperage going through the switch is pretty minimal in that installation, so the relay is not required to keep you safely distant form the current. I switch on LEDs and cathodes with a direct connection to the battery via a switch all the time.

How I'd do it would be to run two positive wires to the flex strips - one going from the OEM white lamp positive wire (will come on when the door is opened just like happens now) and a SECOND wire (use a 3A fuse for just a few strips) going from the battery to your switch and from there to the flex strip. You only need one ground wire.

OR... you probably have a switch already in the cabin to turn on the cabin lighting manually - that's all I do in my MINI when I want my blue cathodes and LEDs to light - I either open the door OR I hit the OEM switch that turns on my cabin lighting manually. If this is so, all you need t do is wire the flex strips to the OEM white lamp lead. Almost every car has some sort of switch to turn on the cabin lights - it's usually near the dimmer switch for the gauge lighting (in GM cars) or it might be a seperate switch near the dome light (like it is in my MINi). This is simpler and less wiring.

If you're positive that you don't in fact have a switch to turn on the cabin lights manually, or that just won't work for some other reason (such as you want to only turn on some of the flex strips with a switch and have the strips and other lights come on when the doors open) then by all means go ahead and use a separate switch...