New guy here. HI! The security system on my 98 GMC K1500 will allow the engine to start, but dies immediately. This may occur everyday for a week. Then it may start and run fine for a couple of days. Then back to the start and die scenario for a few days. I bought a bypass module from Newrockies and it actually doesn't completely bypass the PasslockII system. (They told me this later.) Anyone know how to access the ECM/BCM to delete the security program?
quietone
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I had the same problem with an 02 grand am. My eventual fix was to find the two wires coming from the ignition that go to the computer(mine were white and yellow I believe) I disconnected one wire and hooked a resistor between it and the other wire, then reset the computer to relearn that resistance. Never had a problem again.
Well there's two ways to go about it. You can either try and match the resistance that it has right now and then you wouldn't have to reset the computer, or you can do what I did and just pick a random resistor to throw in and re-learn it. I can't recall what size mine was, probably in the30-50 ohm range. I don't think it actually matter what size you pick, so long as you do a reset once it's all in (and maybe don't totally seal the connections until you try it just to be sure)
Problem is the Passlock II system doesn't use a resistor in the key or switch. It has a magnet in the cylinder that generates a voltage when the key rotates the ignition switch. This pulse goes to the EVO module, which sends a signal to the BCM, which sends a coded message to the ECM to turn the injectors on.
When it fires up and creates a voltage across the cylinder, the computer uses that to measure the resistance. For whatever reason sometimes it screws up. All I know is when I bypassed mine with a resistor I never had the issue again
Got lucky on mine and just disconnected the wire going into the actual ignition cylinder. No resistors, nothing...idiot light stays on, but if I use my power locks, I still have full security arming (I don't use the remote...little prick was aiding the problem).
I figured I would resurrect an old post because I have the same question for the 98. I have HP Tuners and the 98 5.7 is listed as a supported vehicle so I thought it would be a simple matter to unlock and delete the theft deterrent system in the VCM (understanding all the pros and cons of keeping a security system). However, when trying to re-write the VCM it is unable to read without I'm guessing something from the EVO/Passlock module through the purple serial data wire?
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