Switched Power Source in the engine bay, easy peezy?

[CanuckQx4]

Hey guys, I am installing an electric fan into my 2001.5 Qx4 and the relay wiring requires a switched power source to "arm" the relay I suppose youd call it.

What would be a good source in our engine bay? The kit comes with those splice connectors but I will probably use a blade to cut a portion of insulation off to expose the inner wire and solder right to that.

Im unfamiliar with where a good spot or suggested source would be for a switched signal

Thanks for any help

[Towncivilian]

I used a T-tap to tap power from the OBDII 12v switched wire, ran it through the clutch plate blank and to the relay box at the driver's side. I used it for independent fog lights. I couldn't think of a wire to tap from within the engine bay.

[CanuckQx4]

The way you wrote that makes me think youre talking about a wire that goes to the cars OBD2 port?

I also have some foglights to install but am waiting to get the car on the road Nov 1st to figure out its little problems before I go installing fun stuff.

The e-fans were only installed because the factory fan blades were cracking badly and I didnt trust them to not fail. So thats why Im installing this fan controller

[barnum]

I recently did an e-fan swap. I have the Derale 16738 fan controller which requires the relay to be grounded, ran to the battery, and to a switched ignition source (see below). I mounted the relay near the battery on the passenger side and there is a fuse box directly behind the battery which has a few switched sources, just pull a fuse insert the wire and plug the fuse back in. No need for soldering. Just pick a fuse location that can handle sufficient current.



If you opt for a manual switch instead of wiring to your A/C, the same can be done at the fuse block behind the change tray on the drivers side just under and to the left of your steering wheel. This allows you to install the switch near your mirror adjuster and cab light dimmer if there's an extra spot.

[CanuckQx4]

I dont really mind opening up the bottom of the fuse box to strip some insulation and solder directly, I just trust it more that a wire jammed in there.

Im hoping to narrow down which fuse and wire color would be switched I suppose so Im not going in blind, any idea what circuit you tapped into?

Thanks for the help guys

[Chuck Tribolet]

Barnum: there should be a fuse in that red wire between the battery and the relay, as close as possible to the battery. Always fuse close to the power source.

[barnum]

Chuck, you're correct there is an inline fuse in the red wire to prevent frying the relay. Though, if I'm not mistaken, Canuck is referring to finding a switched source for activating the fans rather than the relay power source (please confirm).

You can either wire what would be the "yellow" wire in the diagram above directly to the battery or a switched power source. Wiring it to the battery will allow it to run if fan thermostat switch is closed even if the car is off. I didn't want the possibility of the low grade thermostat I have going bad and draining my battery inadvertently so I ran it to an ignition switched fuse in the block which is near the battery and fan relay.

I will admit that I am no electrician so if my logic is confirmed to be bad, then don't listen to me Canuck. I can't remember which circuit I've got it in. I'll try to snap some pictures sometime today of my fan setup and show where I've got everything hooked up. Also, having an idea of what current draw your fan setup will have will help you determine a proper location to switch from.

[Chuck Tribolet]

The fuse wasn't shown in your diagram.

The fuse isn't there to protect the relay but rather to protect the wiring and prevent a fire.

And given that there is a fuse in the red wire between the relay and the battery, the two fuses by the fans are redundant.

[Chuck Tribolet]

The G/W (Green with White stripe) wire to the A/C relay would be a good place to pick up switched power under the hood.

[CanuckQx4]

Thanks alot Chuck I was about to wing it tomorrow morning and poke around with the test light to find switched. May try it later on tonight now that I have a starting point. Really wish I had adhesive shrink wrap on hand