View Full Version : Fuel cutoff/ ignition cut off protection

02-27-2006, 02:15 AM
I was curious about different ways I could immobilize my ignition. I don't have tons of money for an alarm, and frankly, they often don't do much (unless its something like lojack).

I was wondering how I could maybe wire a button on my dash to allow my car to start up. Maybe something like my power mirror has to be set to the right mirror for it to start up or something similar. What would I have to do with the ignition wiring to allow for this?

02-27-2006, 08:27 AM
wire it to the ECU power. No fuel--no start.

02-27-2006, 08:40 AM
You can intercept the ignition 1 & 2 wires under the steering column and use a hidden toggle switch. You'll need to use a relay to control cutting the power since no toggle switch can handle that amount of juice flowing through it. That and the fuel intercept are your 2 best options.

I'll be doing something like that in my Project Nissan truck. I will have no ignition key in the truck. I will have a hidden ignition/accessory power switch hidden along with an Ignited brand push button as the ignition start.

02-27-2006, 10:56 PM
there is that useless button on the steering colum that turns the parking lights on. you can wire that to a relay that controls the computer, or the fuel pump. My dodge ram had a relay that controlled a fuel shutoff because it was a diesel. and diesels dont fire off spark so to shut them off you need to cut the fuel, so you can also do somthing like that. but that switch would be perfect for that. I really dont know anyone who ever uses it for anything except to kill their battery when they bump it...

02-27-2006, 11:00 PM
or using them when they're parked and they dont' want to run the engine ;)

But I agree, they're pretty easy to bump (I always hit it when I'm doing stuff around the guage cluster or w/e).

02-27-2006, 11:57 PM
Ok, so now its just a matter of figuring out which wire is power to the ECU. I need to read more, because I really don't know what I am doing when it comes to wiring.

02-28-2006, 12:21 AM
pretty much can cut wiring to the fuel pump relay, or to the main relay either would give you the results your looking for.. but the ignition is another because no spark = no start... only problem is there it will flood out the engine if its still pumpin fuel in

02-28-2006, 12:29 AM
actually your best bet would be cutting either the yellow wire that switches the fuel pump relay when you turn the key, or the yellow green wire that feeds the fuel pump.. if you cut the main relay it would still run but really crappy because thats really just controlling all the sensors......... not actually the power to the ecu.. so if you tapped into that yellow wire right after the fuse with a relay controlled by your hidden switch you would get your imobilizer

02-28-2006, 01:05 AM
Ok, so would I chop the wire completely, then on one lead run a wire to a switch, then from the switch connect to the other side of my now, cut yellow wire? Is that all I'd need to do is put a switch in which when off leaves a gap in the electric circuit for the fuel pump (thus no starting), but when the switch is on, it connects the circuit and everything is good?

Do I have to worry about any kind of fuses or relays or anything like that, and if so, a brief explanation of what and why. Again, wiring is a complete mystery to me.

02-28-2006, 02:55 AM
ok you would need to wire in a relay because a switch has too much resistance and will heat up and possibly catch on fire or just stop working. the whole concept behind the relay is that there is a small magnetic coil in it that when you put power to it the magnet pulls a larger contact over that can handle the high ampere.. so with that in mind you would want to get a power wire to your switch, and then the wire coming off the switch would go to one side of the relay, and then there would be a ground on the relay, and then on the other 2 leads you would want to connect the 2 sides of your cut yellow wire.


Here is a link to a relay you can use.. this is the relay that I used for the diagram above. so the numbers on those leads go with the leads on this relay. You can probably also pick one up at a radio shack cheap.. But I dont know if they have anything rated high enough for that. I believe that is a 15 amp fuse its coming off of so it would have to be rated for 15 amps or higher
http://www.partsexpress.com/pe/showdetl ... er=330-073 (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=330-073)

02-28-2006, 01:18 PM
Top notch explanation. Thank you!

02-28-2006, 03:23 PM
Glad I can help