Chevy Passlock problems

The battery on my 2005 Chevy Classic (AKA Malibu) went dead so I had it replaced but the anti-theft “Passlock” circuit got tripped. What a royal pain! All my neighbors now hate me because the alarm just kept screaming so I disconnected the ground wire on the horn - big mistake because the anti-theft was then convinced someone was stealing the car.

To reset the alarm you have to leave the key in the “on” position for at least 10 minutes listening to that damn alarm the whole time. To resolve the issue I filled the alarm horn with caulking then went through the reset procedure without having my ear drums bleed.

What a dumb mess, G.M.

I wonder how the computer senses the horn is disconnected? All it can do is measure resistance, so you could replace it with the equivalent power resistor.

You must be right but as long as that wire was disconnected the odometer kept flashing and you can hear a flasher clicking under the dash even when the key is removed. That went on all night killing my new battery. That’s when I figured I’d better get creative.

That’s modern living I guess.

Today’s vehicles are a whole lot safer but with new technology…more irritating problems occur. It’s a fact of life. I love simple vehicles but the trade-off is safety. I’ll learn to live with safer cars and trucks.

I agree, missileman, technology has made vehicles a lot safer but the problem with my “anti-theft” issue is that the technology caused the problem. It didn’t provide any benefit. Replacing the car’s battery shouldn’t result in all this frustration. What’s even more absurd is the whole “Passlock” concept. It does not prevent car theft it simply frustrates the owner.

…and I agree with you jerryehr because most car alarms don’t prevent theft in the least. It’s an outdated concept but most people feel good that they have one installed. What they really are is just a way to tick off the neighbors at 3AM.

Can the alarm system be reset by clicking the LOCK button of the keyfob? My Soob works that way but don’t know if your system does.

missileman: My car came from the factory equipped with a nearly foolproof anti theft device in this day and age. It’s commonly known as a clutch pedal.

Thanks for the chuckle sgtrock21 and it is nearly foolproof. A friend of mine owns a transport service and has a couple of standard shift trucks. He has nearly 40 employees but only two of them can drive a stick shift…one of them is his mechanic.

On a recent Car Talk show the brothers said one of the best anti-theft gadgets is to install a hidden switch somewhere, that prevents the ignition system from being powered up. That’s pretty easy to do, and seems like it would be at least as difficult to defeat as the modern systems.

Sorry, Cougar, I didn’t get back to you. No, pressing any button on the fob does not solve the problem. The anti-theft circuit is simply broken because besides sounding the alarm it’s also supposed to disable the distributor so the engine cannot be started. The engine starts right away.

It’s simply a defective, worthless circuit and/or buggy software.

No Problem on the delayed response. Have you tried to reprogram the remote just to see what happens by doing that?

No, I don’t know how to do that. It’s not mentioned in the owner’s manual and, of course, GM offers no information online.

Do you know how to do that?

For $115 dollars I can take the car to Chevy dealer for “diagnosis” and they will probably fix the issue for me (at an additional charge) but they won’t tell me how I could have done it myself.

Any help you can offer would be greatly appreciated.


Is there still a problem with the vehicle? In your original post you explained your remedy. If the horn is sounding you must have an add on alarm system, I don’t believe the passlock system sounds the horn.

Thanx, Nevada! You are right, I forgot that car has an after market security control.

It was a major pain in the backside when I bought the car (used) so I removed the battery from the remote and threw it in the glove box 'cause I didn’t want to fool with it any more. I put the battery back in the remote and pressed the disarm button - fixed the alarm issue.

I was convinced the alarm horn was installed by GM because when I removed that horn (to fill the thing with caulking) there was a sticker under it saying “Do not remove” with the GM logo on it.

Note to self; if I ever need to disconnect the car battery again I’ll need to dig out that remote, again.

Alarm systems can be more troublesome than they are worth.

Whatever you do replace that horn when you get this all sorted out.

I have a friend who did not know that the previous owner had disabled the horn on her car alarm. Her daughter was dating a guy in a seedy part of town and someone attempted to steal the car 4 times in one year.

They never got the car out of the driveway…which is good, but each time, they did so much damage to the steering column that she spent at least $500 each time for repairs.
Had the horn blared…the thieves would have given up and ran for cover, but because there was no alarm sound, they stayed and trashed the column and ignition trying to steal it.


So in hindsight there really wasn’t a problem with the Passlock system but rather with an aftermarket alarm system? I assume you will remove/have removed the aftermarket alarm in its entirety soon before it causes you more trouble.

Correct, asemaster, the whole issue was because of that annoying after market (Avital) alarm and no, Yosemite, I will not replace that hideous alarm horn because a thief would do me a favor by stealing this crappy car.

You did not bet my point @jerryehr.
The thief will not be able to steal your car. because the ignition is disabled by the alarm system.

But the thief does not know this because a horn blaring, did not cause him to grab his tools and run. He thinks he can steel it and drive off. He breaks the ignition out…does $500 damage and then gives up.

Your hope that they steal your car is understood, but you will end up still having the car in your driveway with damage that makes it undrivable to you and a tow bill to have it fixed.