Factory key with computer chip help!!!???
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Factory key with computer chip help!!!??? Does anyone know how to bypass the alarm on a 1998 z28 as in bypass the computer chip for the key......car sometimes wont start because of this really frustrating help please 
Joined: Nov 2003
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From: Jacksonville, FL (originally from Toronto Canada)
First of all, the chip on the key isn't a computer chip - it's a simple resistor. There are 15 different resistance values GM used for its keys. The body control module (BCM) checks the resistance of the key in the ignition when starting. If it matches the value it has programmed then it allows the car to start, otherwise it shuts off the starter relay and the fuel supply to the engine.
It is fairly easy to bypass if you have some electrical experience. All you have to do is disconnect the wires that go to the ignition cylinder and connect them together with resistors that match the programmed value in the BCM. That way the BCM sees the proper value all the time. A quick search on "VATS bypass" will get threads on how to do it including photos.
You may not need to bypass the system. Since your problem is intermittent, it could be the result of a dirty or worn key, or grime in the ignition cylinder. That will change the resistance causing the system to think the wrong key is being used. Clean the contacts on the key pellet using a pencil eraser and some rubbing alcohol. Clean the ignition cylinder by spraying in some contact cleaner (or TV tuner cleaner) available from Radio Shack. Also, try your spare key to see if the original key is the problem.
It is fairly easy to bypass if you have some electrical experience. All you have to do is disconnect the wires that go to the ignition cylinder and connect them together with resistors that match the programmed value in the BCM. That way the BCM sees the proper value all the time. A quick search on "VATS bypass" will get threads on how to do it including photos.
You may not need to bypass the system. Since your problem is intermittent, it could be the result of a dirty or worn key, or grime in the ignition cylinder. That will change the resistance causing the system to think the wrong key is being used. Clean the contacts on the key pellet using a pencil eraser and some rubbing alcohol. Clean the ignition cylinder by spraying in some contact cleaner (or TV tuner cleaner) available from Radio Shack. Also, try your spare key to see if the original key is the problem.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Thread Starter
Registered User
Joined: Apr 2008
Posts: 24
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Well i was just wondering but it is the only key i have to the car and i took it to a mechanic who claimed it was a computer chip and says he can bypass it but after looking at the thread you were talkin about its clear i can do that haha since i am an electrician
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Joined: Jan 2006
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You may not need to bypass the system. Since your problem is intermittent, it could be the result of a dirty or worn key, or grime in the ignition cylinder. That will change the resistance causing the system to think the wrong key is being used. Clean the contacts on the key pellet using a pencil eraser and some rubbing alcohol. Clean the ignition cylinder by spraying in some contact cleaner (or TV tuner cleaner) available from Radio Shack. Also, try your spare key to see if the original key is the problem.
