How to: 12v Relay

[xoxbxfx]

For your needs:

Key switched power goes to pin 85
Temp switch goes to pin 86
fused + 12V directly from battery goes to pin 30
fan motor (+12V) goes to pin 87

With this wiring, the fan will only come on when the key is turned on AND the temperature switch is also on.

not to bash your skillz...but are you sure?

Here is a pdf of a negative trigger relay setup I found for an alarm...should work on the same principal. I was questioning myself so I googled it... It should be setup like the 2nd example.

http://www.koolglo.com/BOSCH1.pdf

 

[norcalsvt]

Even after doing searching I have come across a few different ways to wire the relay. Not sure which one to use. Maybe I'll just have to do both & see which one turns the fan On/Off correctly & if the fan is running which one will shut the fan off with the ignition off

 

[xoxbxfx]

Even after doing searching I have come across a few different ways to wire the relay. Not sure which one to use. Maybe I'll just have to do both & see which one turns the fan On/Off correctly & if the fan is running which one will shut the fan off with the ignition off

Im really thinking my way is correct...you really got me thinking. You want a ground to trigger... so a ground closes the relay on, where normally a hot does... so that means your trigger (86) is ground.

You want to send a ground to your fan since its negative trigger. This means your hot source goes from the battery directly to the fan. When the relay closes, it sends the ground out to the fan and completes the circuit. So 87 is ground, and normally this is +.

If you put a hot source on 30, its going to try and pass a hot source through 87 like it normally would. So you would want 30 to be a ground to complete the ground circuit.

So 85 is where the + source goes.

 

[Tim65GT]

Trying to wire in a relay with a temperature on/off switch. The switch is supposed to turn the fan on @185* & OFF @170*. It is supposed to ground by screwing into the intake. the switch has one connector on top.Don't have the relay wiring anymore, so trying to make my own. As far as the relay wiring, would I connect 12v power from the battery to 30, temperature switch to 86, ground to 85, & fan motor to 87. If this is correct will the fan turn off when the ignition is off? It seems like I am missing a switch power source. Where should this connect on the relay?

It won't work like this. You have ground across both sides of the coil.

by Bottlefed:

Key switched power goes to pin 85
Temp switch goes to pin 86
fused + 12V directly from battery goes to pin 30
fan motor (+12V) goes to pin 87

With this wiring, the fan will only come on when the key is turned on AND the temperature switch is also on.

This will work.

 

[ForceFed70]

not to bash your skillz...but are you sure?

Here is a pdf of a negative trigger relay setup I found for an alarm...should work on the same principal. I was questioning myself so I googled it... It should be setup like the 2nd example.

http://www.koolglo.com/BOSCH1.pdf

Yes I'm sure.

I think you are getting confused with how the relay coil works. It doesn't have a polarity. So long as there is 12v across the coil, it will throw the relay. If you look at a wiring schematic for a relay you will notice that polaritys arn't marked... that's because it doesn't matter. He could reverse the wires going to pins 85 and 86 and it would still work.

 

[xoxbxfx]

Yes I'm sure.

I think you are getting confused with how the relay coil works. It doesn't have a polarity. So long as there is 12v across the coil, it will throw the relay. If you look at a wiring schematic for a relay you will notice that polaritys arn't marked... that's because it doesn't matter. He could reverse the wires going to pins 85 and 86 and it would still work.

right on... thanks for teachin me something.

 

[valley82]

Yes, the coil needs one side hot (or +) and the other side ground (or -).
this will activate the relay (normally open "n.o." switch "contacts" will close while the normally closed "n.c." switch "contacts" will open).
In it's most basic form, you flip a switch on your dash "closing the circuit" letting the positive "+" electricity flow to the relay coil. The relay coil energizes activating the relay, any loads "lights, stereo, underdash lights, etc..." on the n.o. terminals of the relay get power "turn on" while any loads on the n.c. terminals loose power "turn off".
Hope this helps???
Think of electricity as if it was water, the wires are the pipes that carry the water, and the switches, relays as the valves (they stop the flow or let it flow). The switches are called out when in the non powered state. n.c.-normally closed (power will flow through when the relay is not powered)...n.o.-normally open (power will flow through when the relay is powered.

 

[norcalsvt]

Ok. Finally reached a consensus. I will go with 85 Switched 12V- 86 Temp Switch- 87 +Side of Fan- &30 12V from battery w/inline fuse. Thanks for everyones help.