Anyone know how to disable the GM Passlock II system?

Question

I have a 1998 Chevy Malibu. The geniuses over at GM decided to install this stupid "passive" anti-theft system called Passlock II which turns off the gas to the engine if a key is inserted into the ignition that doesn't belong there. The Anti Theft light will come on and blink for 5-10 minutes, even if the right key is used. It's kind of an intermittent problem, but it's already made me late for work once. As soon as the light stops flashing, the car starts right up perfectly.
Does anyone know how to disable this system easily, and hopefully inexpensively?

The car is neither stolen, nor has the ignition been tampered with. It is a very well known problem with the Passlock system, and with Chevy Malibu's as well. And I have two keys, and both of them work exactly the same.

Answer 1

The wires that the above answer mentioned are located within an orange sleeve that runs from the switch to the on board computer. the wires usually are white. sometimes one is striped. What you need to do is cut one of the wires and strip the ends. next put the car in gear. (not park or neutral) connect a digital ohm meter to each end of the wires you cut. Now turn the key to the start position. The car will not "turn over". You will get a reading on the ohm meter. This is the resistance of the chip in the key. Go to radio shack an purchase a resistor that matches the value on the ohm meter. Sometimes you need to but two resistors and connect them together to get the proper resistance. Now cut the other wire in that sleeve.Connect the resistor to the wires that you cut. This will trick the computer into thinking that there is always a key in the ignition. You'll still need a key to start the car, but it doesn't need a chip in it. Sure is nice when you have to get a key made. You don't need to go to the dealer for that great GM feeling when you have a key made.

Answer 2

There's a way to do it by tracing the two wires going down the column for the ignition cylinder contacts, finding out what the resistance value is for the chip in your key and installing a resistor of the same value in the harness connector for the two column wires....this will defeat the system and allow anyone to start the car without the right chip key although they'd have to have the right key to turn the ignition or peel the column to steal it. If the car has a computer problem, then that won't work. Could just be dirty contacts in the ignition cylinder if it's an intermittent problem. Try cleaning the contacts inside the ignition cylinder for the chip with some rubbing alchohol or contact cleaner and a q-tip.

Answer 3

Has this car ever had a remote start system installed? If so then I have seen instances where those geniuses have spliced into the PassLok circuit at the ignition cylinder. Their connections are interfering with the password that is being sent to the BCM and then to the ECM. Bad password, no go. This system isn't stupid, it's just the people who try to diagnose them aren't quite up to the task. This is a very easy and well thought out security system. You're just frustrated that it hasn't been diagnosed correctly. There is no chip in the key. I would split the column trim covers and inspect the wiring at the cylinder for breaks or loose terminals. If you go to a "good" Chevy dealer, they should be able to diagnose your concern.

Answer 4

Passlock 2

Answer 5

all I see in my manual is that u just need to get a new key for the car. unless your driving a stole car
book says if correct key isn't used or ignition lock cylinder has been tampered with car wont start

Answer 6

The passlock sensor went bad in the lock cylinder. Wouldn't it be less headache to have the lock cylinder replaced? What if you cut the wrong wire and make the problem worse, or what if you cut it and it does no good? Why would you make an inexpensive problem into a big problem?