pnwjdm

before i even begin... no i dont care that everyone on here will know. not like people know where i live.

Ok now to this. i got a friend with a ek hatch and he asked me if i could wire in a killswitch for the fuel pump to the rear defrost button. so to start the car it would need to be pressed in to start the car. How can i accomplish this? can the button hold the load for the fuel pump? thanks

jbpnoman

The button can, but if he wants it on the fuel pump power wire, he'll need to have the rear defroster "on" to run the car always, not just to start the car.

As far as the "how", it's easy, and he can retain functionality of his defroster (although it'll always be on). Buy a 4 pin relay. Patch it into the wire that runs back to the window, via the signal and signal ground pins on the relay (85 and 86, orientation doesn't matter). Cut the fuel pump power wire into the other two pins of the relay (30 and 87, orientation doesn't matter).

lazlong

The defroster circuit isn't meant to always be "on". You'll burn that circuit out fairly quickly. You'd be better served buying another switch, installing it in an empty slot and making that the defrost. Then you can use the original defrost switch as the kill switch:


Or do it jbpnoman's way:


BTW: The vast majority of relays you'll find out there are 5 pin. They're OK to use, you just don't use pin 87A. I would recommend covering it so nothing ever touches it.

jbpnoman

The vast majority of OEM relays, sure, but if you're doing aftermarket wiring, you can easily buy a 4 pin "generic" relay with a harness on Amazon for a LOT cheaper than buying an OEM relay. That's what I did for the custom wiring for my power seat retrofit.

lazlong

I am talking aftermarket relays, just go down to the local electronics store and most, if not all, are 5 pin. It's because you can do more things with a 5 pin. OEM are the ones that are usually 4 pin.

jbpnoman

I've never had a problem finding 4 pins. Always better to use the proper part for the job.

lazlong

In OEM locations the OEM relay (4 pin) is proper for the job. In an aftermarket situation it doesn't matter because they both do the same thing in the same way. In other words, they're both "proper" for the aftermarket job at hand. I'm just telling him the 5 pin is ok to use IF he can't find a 4 pin.

EsotericImage

iTrader: (8)

Interesting..

I was planning on using my Cruise or AC button for nitrous arming but havent gotten to research how to do it.

TripleLude

You could have the switch trigger the main relay, instead. Then, no fuel and no spark when switched off, and no cutting of the fuel pump wire. The main relay is right there around the driver floorboard, right?

jbpnoman

Comon now Eso, this is wiring 101 type stuff