How to bypass ignition switch security?
 

Here is my situation....I am building a completely custom car from the ground up. I purchased a 2006 Monte Carlo SS for the engine to use in this creation of mine. I removed the engine and every inch of wiring from the entire car (Because I didn't know what I would need and what I wouldn't). The car I'm building will incoporate from the Monte the following:
-Engine/Transmission
-Fuel-tank and pump
-Instrument cluster
-Accel. Pedal (Due to the fact it is drive-by-wire)
I laid out all the wiring and harnesses on the garage floor and started working my way back to the BCM (body control module) with the help of a factory service manual, disgarding what wasn't necessary for my application. The problem I have run into is with the ignition switch. The security on this car uses a programmed key in conjunction with an "exciter" module inside the steering column. The way I understand it, if the key and the exciter agree that they are meant to be together, it (the exciter) sends an O.K. signal to the BCM and the BCM, in return, says to the engine it is safe to start and run. I am not going to have a key for this car, it will be a couple switches for the accessory and run positions and a momentary button to start.

My question is what exactly is the signal that the exciter sends to the BCM (specific voltage, digital signal, analog signal, etc?) Is the signal, at this point, uniform from vehicle to vehicle?
And finally, if it isn't possible to determine the signal and/or replicate it, is there a way to bypass the BCM completely and simply supply a voltage to specific outgoing circuits (ie. the fuel pump, ignition control?)

If you can help (even a little) please let me know and keep it as simple as possible because, by no means am I an expert on the automotive electrical system! I am learning as I go....

Thanks,
Neil

RE: How to bypass ignition switch security?
 

hmm ive never had this situation before...ill have to think a lil more but this is all ive got off the top of my head...when i installed my remote start i had to cut the ignition signal wire and run the security bypass module between the two parts of the wire...this module has some safetys like if u depressed the brake pedal the car would shut off so you couldnt put it in gear...maybe if u didnt connect that wire you could use the remote to start and actually drive the car without the key...ill give it some more thought

RE: How to bypass ignition switch security?
 

I will look into the aftermarket remote starters to see if one of them could be used in place of the ignition switch and exciter. I would prefer the simpler and cheaper route of just bypassing or re-routing a few wires if possible. Thanks for the suggestion and let me know if you come up with anything else!
Thanks,
Neil

RE: How to bypass ignition switch security?
 

well unfortunately rerouting wires will most likely not work...the security system that gm uses (passlock I II or pats) uses a resistance base system and without that resistance in the pcm will not allow the power to be sent to the starter and the car cannot be started, now that i think about it you could prolly use just a security bypass module without the remote start and just reroute the wires to simple switches...but then u must figure out how to get the switch to shut off once the engine starts so the starter motor doesnt continue to run once the engine has started

RE: How to bypass ignition switch security?
 

I bypassed mine by measuring the resistance between the 2 wires and then soldering in a resistor. This tricks it into always seeing the correct resistance and therefore bypasses the security check. I have a guide and pictures if your interested in doing it yourself. Takes a couple hours, a multimeter, soldering iron, resistors and thats it.

RE: How to bypass ignition switch security?
 

that is exactly what the security bypass module would do...except much cheaper

RE: How to bypass ignition switch security?
 

X2. For my alarm I got the DEI bypass module. Cost about $50 if I remember right. You can get them at Best Buy where they do stereo installs.

RE: How to bypass ignition switch security?
 

if not can you use the stuff out of the corvettes. they have push button starts. or even cadillac might use something that may plug in???????

sounds like a fun project can we see some potential designs of it?????

RE: How to bypass ignition switch security?
 

would you need to use the whole wiring harness out of corvette if u did that?

RE: How to bypass ignition switch security?
 

i would think so. :)