Anti-Theft light stays on 24/7. No passlock sensor on the ign lock cylinder. Stumped.

Asked by Jan 10, 2015 at 06:01 PM about the 1995 Chevrolet Cavalier Base

Question type: Maintenance & Repair

My "Anti-Theft" light stays lit. Starter will engage and engine turns but will not fire. I thought it may be a passlock issue. There is no passlock sensor on the ignition. I've been told it may be an instrument cluster issue but have had no success in finding a solution other than buying a new instrument cluster. This light came on and stayed on a few weeks ago and the car would start when it felt like it. Sometimes in neutral, sometimes in park, sometimes not at all either way. Now it cranks til the cows come home but won't fire. I've taken the entire dash and steering column covers off with no luck. All fuses are good/have been tested. What am I missing here? Any insight or help would be greatly appreciated. I've been searching relentlessly for the past four days and have read every forum asking about the passlock system, ways to disable it, diagrams, pictures. I am stumped. Not sure if someone jury rigged it before since the sensor is missing or if it's using prior model year parts. It's a decent cheapo econo car that has run great for the past 9 years for me...only has 94k miles on a 20 year old car. Can I just wire up a push button start?

5 Answers

I can't imagine why somebody would tell you it's an instrument cluster problem. That's out in left-field. Since it has no passlock, you mean does not have transponder key? A key with a plastic head, or just a plain metal head key? I am thinking your brake light switch. That's the safety interlock, you have to have your foot on brake to start and if the brake light switch is loose, it may be working sometimes and sometimes not. I don't know if I am any help, just tossing thoughts

No, wait. I re-read your post and if it was the brake light it would not crank over,,sorry 'bout that

"Passlock Testing this system is similar to the Passkey I and II systems. You want to check the voltage at the bottom of the steering column as you insert the key and rotate it check the yellow signal wire (should be 5 volts before you start the testing). Turn the key. The value should drop. If it does not, you will have to replace the key cylinder. The “control module” for this system is built into the instrument panel control (IPC) in early years. In later years, the system is controlled by the Body Control Module (BCM)" http://ricksfreeautorepairadvice.com/gm-anti-theft-systems-overview/

"The key cylinder housing has a small magnet that rotates past the Passlock sensor. The sensor is powered and detects the rotation. The voltage on the sensor then drops to a specified value (there are 10 different values). There’s no pellet in the key. So basically this system is checking to see that a thief has not popped the lock cylinder to steal the vehicle."

My key cylinder has the indent for that sensor but no sensor is present. There is no chip or pellet in the key.

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