Hidden kill switch for H3T

[SkinGripz]

Did a search, got nothing.

Wanting to install a kill switch on my new H3T. Plan to use the off road light switch as it wont be thought of as a kill switch by a thief. Dont know exactly how to wire it to keep from ticking off the factory systems. Ignition or fuel pump? Any help appreciated.

Have one on wifes maserati that uses the cig lighter, but had a pro do it, so dont know how it was done. He moved away last year. Basically, car wont start without the lighter in place. When she parks in a lot, she takes the lighter out and drops it in the cup holder. A thief just doesnt consider that it has anything to do with the car not starting. Has saved it once in Dallas. Broken window, and ten bucks missing from console, but car still there.

Thanks in advance,

Mike

 

[SolidusJ]

Sounds like a pretty sweet set up but does the lighter shut block battery power to the Maserati? I know this might sound dumb but wouldn't that make the radio station you set up erase every time and anything else that needs some power to stay in the memory?

 

[SkinGripz]

No, it was done in line with the fuel pump. All power to radio, locks, dash, etc still work, but fuel pump wont run without the lighter in place. The few times I have forgotten (she doesnt let me drive it much) is cranks but does not start. Think it caught once, but stalled in a few seconds.

i know its a simple two wire job, just dont know which two wires on the hummer. The factory security, passkey, microchip stuff, is different, and I dont want the truck getting pissed.

 

[SolidusJ]

That's freaking awesome man!!!

 

[3Hummers]

Have a manual key kill switch on some of my H1s but they aren't electronic, all mechanical. Mine kill the connection to the battery. Works great. I have no idea how to do it without pissing off the electronics on an H3. Maybe Doug will post up on this.

 

[Happy Hummer]

Interesting.

Chris

 

[f5moab]

Easiest would be to interrupt the start signal from the ign switch to the BCM. White/green wire (pin 3) at the ignition switch probably easier to tap into at the BCM where it is a dark blue wire into the large gray connector, pin B8. Or go under the hood and interrupt the PCM sig to the PCM control relay; kiling the signal to the starter.

Are H3s high on the stolen vehicle list? And the BCM start circuit, with the Pass system, is pretty darn good at keeping the fuel pump off after startup.

 

[Mr_Rich]

You could tap in to the starter solenoid wire with a relay. That would be fairly easy. The trick is to keep the circuit hidden and not obvious. Some of my older car books on my shelf at home mentioned that Nascar engines used a kill switch on the ignition. When they start their engines they make sure they have good oil pressure before turning the ignition on.
I was thinking another option would be to keep an internet traceable phone hidden in the car as a back-up LoJack type of system. Possibility?

 

[SkinGripz]

Thanks guys.

3Hummers, yep same thing. Switch just interrupts the power. It is mechanical, but electrical as well. Only problem with interrupting the line to the battery is it will definitely piss the security system off, and can be jumped in 10 seconds. Also, no alarm unless a backup alarm battery is installed (not a bad idea though).

wondering if the positive terminal of the fuel pump were cut, adding a switch in-line, would have any effect on the security?? Wouldnt see why as if the vehicle senses a threat, it cuts power to the pump itself. May trigger a service engine light though if key is turned to "On" and it does not receive a closed loop signal to the fuel pump.

Someone mind cutting those wires and telling me what happens??

 

[3Hummers]

Not at all. Bring your truck by and I will cut those wires for you.

 

[M22KLARS]

Did someone say Maserati? :hmm:

 

[TAPDH3T]

Did someone say Maserati? :hmm:

I know!!!! I thought that sry sumgun!! Lol I get jealous.... lol

 

[SkinGripz]

Not at all. Bring your truck by and I will cut those wires for you.

Way too kind !

 

[Steve #1]

Interrupting the wires F5 mentioned will work. I would not recommend using anything other than a switch or a relay on this wire as anything that changes the resistance the BCM sees on on this wire could cause problems with the PASS key system. There is a wire coming from the BCM that energizes the relay for the fuel pump. I would recommend using this wire as it is the same system that the PASS key uses Someone steeling your truck will power this wire directly to get around the PASS system. IF they try it at the BCM you have outsmarted them but if they do it a the fuse box it won't matter.

The best option is to interrupt multiple systems such as ignition, fuel, just to make it harder and the best way to do that is with an alarm.

That said, in the time I've been hanging out on HUMMER forums I only recall one H3 being stolen and maybe a couple H2s. An H3 is less likely to be stolen as the parts are hard to move as they are relativity rare. Many cares are also stolen by towing these days and HUMMERS aren't easy to tow as you cant just snag one with a wheel lift. I'd say don't worry about it, or if you are worried, go all out with an alarm. Personally, I did the latter.

 

[ArtHummer]

Not on H3, but I will never forget this story.
Costumer called and told me that here car is not starting. She towed it in to shop and payed about $200. The shop charged here 30 min. for diagnostic (another $40). I started to look in it. The engine is cranking good but doesn't start. Checked the gas, fuses, the spark on the plug. Checked for all the hot wires and everything is good in the engine bay. My sought, got to be the pump. had to take some trim of to get to the pump. Checked the pump and it is fine. Checked the "hot" wire and no juice coming to the pump. Checked the f.pump fuse and is good and hot. The wires that go to the pump are hot also. The only thing is possible if the line is broken somewhere. Spend on it already about 45 minutes. To check the wire and fix it i needed to take of all the wiring, Need to take rear sit, all the trim of the side, move the carpet and open all the wiring, find the issue, fix it and put it all back. Shop charged here another 2 hours to do all that... After removing rear sit and few moldings I noticed a wire that does not look like a "car wiring". Thought it is strange and traced the wire. It was going in to the area of the rear door rocker panel... Hmmm. there shouldn't be anything there, no switches, no lights... started to look around and noticed a little switch just under the door lock... Turned the switch on and try to start the car and it is started just fine... We asked the owner and she didn't know anything about the damn switch...
Well, she spend about $500 that day just to learn that she got it.

But, in this set up, they just cut in to the fuel pump line and installed a regular tag switch in the hidden location.

 

[SolidusJ]

Not on H3, but I will never forget this story.
Costumer called and told me that here car is not starting. She towed it in to shop and payed about $200. The shop charged here 30 min. for diagnostic (another $40). I started to look in it. The engine is cranking good but doesn't start. Checked the gas, fuses, the spark on the plug. Checked for all the hot wires and everything is good in the engine bay. My sought, got to be the pump. had to take some trim of to get to the pump. Checked the pump and it is fine. Checked the "hot" wire and no juice coming to the pump. Checked the f.pump fuse and is good and hot. The wires that go to the pump are hot also. The only thing is possible if the line is broken somewhere. Spend on it already about 45 minutes. To check the wire and fix it i needed to take of all the wiring, Need to take rear sit, all the trim of the side, move the carpet and open all the wiring, find the issue, fix it and put it all back. Shop charged here another 2 hours to do all that... After removing rear sit and few moldings I noticed a wire that does not look like a "car wiring". Thought it is strange and traced the wire. It was going in to the area of the rear door rocker panel... Hmmm. there shouldn't be anything there, no switches, no lights... started to look around and noticed a little switch just under the door lock... Turned the switch on and try to start the car and it is started just fine... We asked the owner and she didn't know anything about the damn switch...
Well, she spend about $500 that day just to learn that she got it.

But, in this set up, they just cut in to the fuel pump line and installed a regular tag switch in the hidden location.

You are a trooper man. I would of more or less started to chuck some tools when I had to take out the rear sit. I'm really start to like this idea and hope when it's pulled off, the installer takes a ton of photos and step by step this task:thumbs:.