Fan Switch Relay

[Striker169]

Ok so I have a painless Kit and there is a wire for fan relay, is it just a wire that runs though the harness or is it a positive wire? I dont have a voltmeter so I cant test it anyone know?

[shifty]

I would assume (but you know where that can get you) this:

Typically speaking, if is says "relay", it will probably have power and run to a switch somewhere, then into a relay.

The general concept behind a relay is simple but seems complex at first. Look at the picture below - basically, you supply constant fused power (30) and ground (86) from elsewhere. Then you would run your hot (switched) lead to the opposite post (85). Run a wire from (87) to the fans.

The concept is actually easy: When you throw the switch, power is allowed to hit (85) which is grounded on the other side at (86). This energizes a coil inside the relay which will trip a lever allowing power to jump from the constant fused power source (30) into (87). When the switch is off, power goes to (87a).


If this still does not make sense, look at this flash movie for a dummy's guide to relays:

http://www.bcae1.com/images/swfs/relay.swf

Click the close switch/open/etc buttons on the bottom.

In your case, I would think that the relay line will be attached to the switch shown in the picture.

[FormerMember]

The one on my 18 circuit Chevy harness is a switched hot.

You need a relay to run it.

[Striker169]

Originally Posted by grendel

The one on my 18 circuit Chevy harness is a switched hot.

You need a relay to run it.

So that gray with black wire that says Fan Relay wire is a hot wire? Thats what I need to know I know how relays work I just need to know which side to attach the wireing harness wire to either the positive or ground side of the relay switch.

[FormerMember]

Originally Posted by Striker169

So that gray with black wire that says Fan Relay wire is a hot wire? Thats what I need to know I know how relays work I just need to know which side to attach the wireing harness wire to either the positive or ground side of the relay switch.

it goes to the switching side of the relay. Neither hot nor cold.

You provide a relay with four things:
Constant power
Ground (sometimes not required)
Switched signal (when ever you want it to turn on, this is what that black and grey wire is)
Output

[Striker169]

Originally Posted by grendel

it goes to the switching side of the relay. Neither hot nor cold.

You provide a relay with four things:
Constant power
Ground (sometimes not required)
Switched signal (when ever you want it to turn on, this is what that black and grey wire is)
Output

Could you take a picture of your setup?

[FormerMember]

Sure, when it's re-installed in the truck. Right now, it's sitting in a box.

truck's down to it's frame...

[Striker169]

ok thanks