Thread: Question on wiring fans to a manual switch?

Makes sense. What size fuse do I need do you think? This wouldn't cause any harm to the ECU would it?

You don't need a g-d fuse.

You don't need a wiring diagram.



Wire 9+10 to one pole of a switch.
Run the second pole to a ground.

Stop making it complicated. Don't cut anything, just splice it.

Vadims diagram will probably make your **** explode. The ECU grounds the relay from the factory.

Taiden - does that skirt the issue of the silly OEM fan wiring setup? I seem to remember a lot of stupid diagnoses people would have to go through whenever fans weren't working. That's why I opted to do a direct wire up so I'd never need to worry about it.

No, it uses the bone stock fan wiring setup. When temp gets to 212* or w/e retarded temp it is, the ECU grounds pins 9 and 10. All this does is ground those pins whenver you want, thus turning on the fans whenever you want.

I thought I posted about this on the old sr20forum. I wired up Dudeman258's AC switch to do the exact same thing. I also wired my air bag light to turn on whenever that lead was grounded. This did two things, it told me when I had my switch in the ON position, and it told me when the ECU turned them on itself.

Sweet Thanks again Taiden! Much appreciated.

Post back once you've done it.

Hehe I'm happy there is someone that knows what they are doing, mine is more of a how it would work in theory, not exactly connected to the right wires.

Yeah, that's how I do stuff.. then I check it with a multimeter before I do anything.

Haha if you have the time to look all over the place hehe

On another note, so the fans constantly have power going to them, but it doesn't always have a ground going to it? Seems kinda odd that it would constantly have power but no ground.

Well, now that we are on the topic.

The ECU controls the ground for the relay. The relay then supplies power to the fans. That allows a low current device like the ECU control a high current device like a fan, by using a relay.

Blair seems to have a bigger issue. His fans work, his fuse is good, his relay is good. The relay clicks when the ECU pins are grounded, but the fan still doesn't turn on. I am GUESSING it's a wire with exceptionally high resistance. If anyone has any ideas please post them.

Blair, I'm going to post up a diagram of what I mean for testing your wires.

Edit: you've got your quick fix so i'm not gonna draw it up