Starter Kill

[MASTERBrian]

I have a 95 GMC 2 Door Yukon K1500. Was stolen a few months back and I'm finally settled up with insurance and starting to get her back together. Since they seem to have slim jimmed the door, then they destroyed the column to turn the ignition to steal it, I want to finally add a hidden switch. Thing is, I'm likely not using an actual physical switch....I bought a deal that has a NFC tag and a relay. So when the tag is within 3" it'll open the circuit (switch on) and thus allow the car to start. This isn't specifically for this purpose, but it is 12v and I think they list for door locks or something. I was told about it on a corvette forum I'm on. I might also wire in a parallel switch, just in case and really hide it. Leave it in off position, just in case this fails, so not stranded.

The issue is I'm not really sure what wire to use on this truck. I believe purple is the ignition, but so does everyone else and I think that's a heavier wire than this unit has. I'm thinking 14-16gauge? This unit seems to be 18g or so. Adding a relay is not an option in my opinion as it has one already built in and I'm not that great at figuring that out. Yrs ago I wired in off the coil wire on an older truck I had, but alas this won't have that.

There's a few wires on the bottom of the ignition lock assembly on a black box that is attached. Can I grab one of those? I want something easy to get to, but not common for a thief to look for.

Here's an ignition lock assembly for this truck.

Here's the unit I bought.

[MASTERBrian]

I think I finally located a wire diagram, but it doesn't contain all I was hoping to see. It does show battery to starter to neutral safety to ignition switch.

As expected it's purple from starter to neutral safety then yellow to ignition switch.

Looking again at the module and the diagram I suppose I could cut the purple wire from the starter to N.S. and make the connection there, but to me that seems like a common place to look, though I don't really think a thief would go through that much effort. I'd like to try whatever I do prior to rebuilding the lock cylinder to know for certain what I do works. The yellow from Neutral Safety to Ignition switch seems less common of a wire to splice into. Am I over thinking? Would that still work? Is there a better wire to use?

[RustyPile]

Originally Posted by MASTERBrian

I think I finally located a wire diagram, but it doesn't contain all I was hoping to see. It does show battery to starter to neutral safety to ignition switch.

As expected it's purple from starter to neutral safety then yellow to ignition switch.

Looking again at the module and the diagram I suppose I could cut the purple wire from the starter to N.S. and make the connection there, but to me that seems like a common place to look, though I don't really think a thief would go through that much effort. I'd like to try whatever I do prior to rebuilding the lock cylinder to know for certain what I do works. The yellow from Neutral Safety to Ignition switch seems less common of a wire to splice into. Am I over thinking? Would that still work? Is there a better wire to use?

The purple wire or the yellow one would be the easiest circuit to interrupt.. From there you are over thinking the process.. Use a simple key operated ON/OFF switch. locate it in a remote location -- inside the glove box, under a seat, inside a console, etc.. Park the car, turn off that switch and take the key with you.. A car thief wants a quick process and make a speedy get-away.. He's definitely not interested in figuring out why busting up the ignition switch isn't all it takes.

[MASTERBrian]

I agree those two are probably my best option. As for using another keyed switch hidden somewhere like the glove box sounds great, but reality is that in a car driven often it probably wouldn't get set often. I'm trying to make it so she doesn't have to think about it.

I've got the column apart, replacing everything they destroyed, so I have ready access to the harness. I know the yellow wire is from the neutral safety, at least it's supposed to be. I also see there is a pink. I think it's also part of the ignition system. My fear is they are too heavy of a gauge to run to this relay, but maybe I'm wrong.

Coming off the ignition switch is two wires. I'd say 18g, maybe, one is orange and one is green, they go to the top of the cylinder housing to what I think is a small spring loaded switch, but I can't find it what that is. I think they'd be great wires to tap into if they'd do the job. I just can't find a diagram for the switch.

Here's a pic.

[MASTERBrian]

Ok, just found something about that sensor/ switch. It seems to be called a Reed sensor. According to this explanation, if that isn't sensed power is killed. Am I reading this correctly and that if I cut into that it might think key isn't there and kill the car. That wouldn't be good..... correct me if wrong I guess.

Maybe, if I tap into the yellow wire, which I benefit is the crank/start wire, I will use another relay(and feed the smaller relay of the start kill unit). That way I don't have to worry about over loading it?

Here's what I read about the Reed sensor.......
Secondly, the ignition key position is checked by means of a reed sensor and magnet, that is in an actuated state if the key is fully inserted. As long as the ignition key sensor is not actuated means that the driver has removed it, thereby cutting power to the vehicle, and is promptly going to lock it.

[hwyix]

Did you ever get this to work?

[MASTERBrian]

Originally Posted by hwyix

Did you ever get this to work?

Yes, I did. So far seems to work pretty good!

[hwyix]

thanks

[dmjlambert]

This relay guide shows how to use automotive relays for a whole bunch of topics. Several of the topics are for using something like cigarette lighter to enable or disable starting. https://www.davebarton.com/pdf/RelayGuide.pdf