Hidden kill switch and momentary starter with ECU? - NJFBOA - Home of New Jersey's Camaros and Firebirds

SteveR · 12-17-2009, 02:55 AM

Ok, I've been running this around in my head and can't figure it out, nor find a reliable answer anywhere on the interwebs. I'm looking to install a hidden toggle kill switch for the electrical in a car, and a momentary starter engage after it. My question is, are there any issues to take into consideration with a car with an ECU? I keep finding threads out there with people saying that it can't be reliably done with a computer controlled car. Also, other than the two switches (which I have already), what would I need? The switches are both automotive 50amp.

sweetbmxrider · 12-17-2009, 06:57 AM

http://www.ls1tech.com/forums/nitrou...s-one-pcm.html

they say you can't switch between tunes on the pcm because it will fault, so the vehicle must be shut off, then switched, and then restarted. hope that helps.

LTb1ow · 12-17-2009, 11:13 AM

For the kill, couldn't you wire it in series to the main ignition?

So basically just another key switch... or do you want a like a legit hot lead shut off?

Pampered-Z · 12-17-2009, 11:43 AM

You can just tap into the wire for the fuel pump. Won't have any effect on the ECU.

You don't want to do anything that is going to drop power to the ECM because it will loose it LTBL and need to relearn.

sweetbmxrider · 12-17-2009, 11:52 AM

yeah i have seen a couple of cars with the manual fuel pump switch. much better way of addressing it if its an electric fuel pump.

B4C · 12-17-2009, 12:50 PM

Yeah I woudnt kill the power to the computer as it would have to relearn all its stratagies, killing the fuel pump is a better idea. I like my kill switch tho no one is ever figuring that out.

SteveR · 12-17-2009, 02:04 PM

Quote:

Originally Posted by Pampered-Z

You can just tap into the wire for the fuel pump. Won't have any effect on the ECU.

You don't want to do anything that is going to drop power to the ECM because it will loose it LTBL and need to relearn.

Awesome, that's what I needed to know.

So the kill switch would be wired to the electric fuel pump in series, and the momentary starter engage would be wired to the starter? Would this still require the key to be in the 'on' position to activate the ignition? I still want to need the key as well.

sweetbmxrider · 12-17-2009, 02:53 PM

yes, unless you wired the ignition switch into another switch without a key.

also, depending how you wire the starter switch, it could work with or without ignition on.

SteveR · 12-17-2009, 03:08 PM

Quote:

Originally Posted by sweetbmxrider

yes, unless you wired the ignition switch into another switch without a key.

also, depending how you wire the starter switch, it could work with or without ignition on.

I'd like to still need the key.

Pampered-Z · 12-17-2009, 04:20 PM

Yes, you tap into the wires (positive) going back to the fuel pump relay or starter so that the kill switches are after the ign.

One of the cool ways I've seen this done ( but I'm not sure how they did it ) was the cig. lighter was made into a kill switch. I think they cut the factory wires and built a switch into the base/bottom of the lighter assembly so that you pushed in the cig lighter to complete the circuit so the car would start. Pretty creative way to hide a switch.

sweetbmxrider · 12-17-2009, 04:53 PM

yeah i'm pretty sure you can find switches to go into the cig lighter as well. i think they have nitrous styled ones for purging. stock works too.

gotmudnj · 12-17-2009, 05:00 PM

thats what im looking to do when its warm out. my friend got his jeep stolen so i want to set my car up and alarm and switches to start and all.

1QWIKBIRD · 12-17-2009, 08:02 PM

I had a kill switch like this on my 68 Camaro in high school. Completely different technology, I know, but the cool thing was that the kill switch was on a timer. So the car would start and run for about 30 seconds, then suddenly die. Unless you found the reset button, the car would crank and crank and crank, but never fire. Idea being that the guy might get it started, and get out into the street or whatever, but then he's dead in the middle of the road attracting all kinds of unwanted attention to himself. Seemed like a reasonable idea? Probably good enough to stop an amateur, but if a pro wants your car, he's gonna get your car.

Just remember if your tapping into the fuel pump, keep in mind whether you are tapping into the pump relays (probably the better way) or into the power leads to the pump itself. If you cut power to the relays, the wire gauge and associated switch could be very small and much easier to hide, versus cutting into the actual power leads to the pump which would require larger wire leaders and a bigger switch, making it slightly more difficult to hide.

Kat · 12-18-2009, 01:54 PM

Why not just into the VATS wires off the colum....

SteveR · 03-17-2010, 04:17 PM

ok, so I finally got everything I need for this and the weather is looking good to get this done finally. I got the wiring diagram for the fuel pump and I have one question. I found that the fuse for the pump is located on the drivers side kick panel and the wire runs under the dash. Could I just install the kill switch on the lead to the fuse? Would that hurt anything?

1QWIKBIRD · 03-17-2010, 05:45 PM

Quote:

Originally Posted by SteveR

ok, so I finally got everything I need for this and the weather is looking good to get this done finally. I got the wiring diagram for the fuel pump and I have one question. I found that the fuse for the pump is located on the drivers side kick panel and the wire runs under the dash. Could I just install the kill switch on the lead to the fuse? Would that hurt anything?

I think either way, the preferred method is after the fuse, not before it.

Is fused circuit going to a relay or is it going directly to the fuel pump?

If the fused line is going to the relay, I think you would be ok. Basically you are tying into the trigger wire for the relay, not the load wire for the pump.

If the fused circuit is going to the fuel pump directly, then you want to be after the fuse, not before it. But if this is the case, you need to make sure the kill switch is rated and wired with to handle the full load that the fuel pump could see.

What is the rating of the fuse?

Chris

sweetbmxrider · 03-18-2010, 07:39 AM

couldn't have said it better myself. you don't wanna be burning up switches!

you could also tie the switch into the ground if its near by.

SteveR · 03-27-2010, 01:13 AM

Ok, more progress. I found that the fuel pump relay fuse is in the fuse box in the battery junction box under the hood. The fuse is 20amps, and the switch I have is 50amps so it's more than enough. I got the wiring diagrams on cd (and I'm having trouble saving each as a file so I can post it up here) and it looks like the fuse is after the fuel pump relay. However, the fuse is at the end of the circuit. Before it, it splits off and goes to the fuel pump primer and the second lead goes to the fuel pump relay. After the second wire goes from the primer, it splices in after the relay and then splits again, going to the inertia switch and the second to the PCM.

Would it be safe to test the kill switch idea by simply pulling the fuse and seeing what happens? I'd basically just be cutting the wire from the fuse and splicing two leads in running both into the passenger compartment and tying them into the switch.

I'm going to keep trying to figure out how to post these damn wiring diagrams up lol