Hi, I'm kinda new here but this is something that I haven't really been able to figure out myself. I'm the second owner of a 2001 Monte Carlo SS that was very well taken care of and supposedly completely unmodified when I bought it. It does have some quirks that I'm trying to find the source of though. I think that the previous owner (either deliberately or just to fix another problem) had the Passlock feature of the car physically disabled. Some of these quirks are that the chimes don't work, the settings menu in the radio (I forget what it's called) used for resetting alerts, oil life, etc. doesn't work, and when the key is in the ignition (with the engine off) in the "on" or "acc" position, the check engine light comes on (but goes off then the engine is started) and message center flashes between the battery symbol and the security symbol. Aside from this stuff, the car works fine. The remotes work, the steering wheel controls work, and the overhead display works fine, which I've read sometimes act up when Passlock is disabled. If this isn't a sign of Passlock being disabled, what else could be causing it? Thanks in advance guys!

 

The door chimes on these cars go through the radio. If he ever did anything with the radio, that may have impacted it.

Going into changing the radio, if a radio other then the original one is in the car, the oil life/tire monitor and other years might not work, as it's not the right radio. Can you post a pic of the radio you have or the part number?

As for the things you noticed when turning the key to on/acc mode, the CEL comes on to validate that the light is actually working (so if you go to buy a used car this is a good way to make sure the light is not burned out or removed). The message center, i believe toggles those messages until the car is started. I am pretty sure that is all normal.

If a remote start feature is on this car, that was done after market and that would require a Passlock bypass (which is hardware based). Without it, the car would not be permitted to start with the remote start. The started would crank, but the injectors would not fire.

 

The radio is the stock radio, I'd go out and take a picture of it/check the part number but the car is under 10 inches of show right now. It's this one though, which I'm pretty sure is the stock one: http://replacementradios.com/images/...cdcassette.jpg

The oil and tire pressure alerts come on, but I can't reset them through the radio, I just disconnect the battery for a few seconds.

One last thing is that the radio displays "CAL ERROR" when the car is started, but then works fine.

 

CAL ERROR, that's the key. You have one of a couple of things:
1 - That radio needs re-programmed to your car and a GM Tech II is the ONLY tool that can do that.
2 - This radio has been tampered with!!!

Here's what I know about what you just said about the CAL ERROR when starting the car. Back when I was looking for my MP3 factory radio for my Monte (which was never offered for the Monte I might add), I learned a few things.

First, GM had two radio lines that look the same and use the same connectors (but the pin-outs may vary between the lines). For lack of a better description, I call them the "Car and the Truck" lines. The first MP3 radio I tried in the Monte was a truck radio and the Tech II could NOT talk to it (but it appeared it worked fine until you cycled the key and then it went into "theft lock" mode). FYI - I have a working MP3 factory radio, GM used them in the '04-'05 Cavalier and Venture van (goes in, looks like my original radio, the Tech II can program it and from there, it's like it was meant to be, heck I still have the part number for it).

Second, there were two tricks to "by pass" the theft lock. I never did either trick, but I read about them on different GM sites. First trick was to rig a "kill switch" to kill the power to the radio after you start the car (since it works the first time it's energized, after that, theft lock, you keep "rebooting" it each time).
The trick was to take the radio apart, find the chip responsible for "theft lock" and disconnect a pin to it that provides power. The side effect of this trick, each time you start the car, it will display CAL ERROR.

If a Tech II is unable to program it, for what ever reason, I think the radio was modded to bypass theft lock.

A dealer is your next stop if you wish to pursue the radio. Heck, it may also be a programming issue with the Body Control Module (BCM). But you have all I know about that error and your sityation.

 

It seems like my radio is acting like it has the theft lock chip disabled. Luckily for me, I actually asked this question because my initial intention was to replace the stock radio with an aftermarket one. If the problem is with the radio itself, I shouldn't have a problem with an aftermarket radio, right?

 

From what I know, the CAL ERROR should not affect putting in an aftermarket radio. Just remember, the user interfaces (like resetting the oil life) that you were talking about won't exist with an aftermarket radio (you will need to use the alternative methods). And there is something you will need to do about the door chime (as it routes through the factory radio).

I stuck with a stock radio that would work like my factory one to avoid all these issues (since all I wanted was MP3 playback on CD). The radio I got was $50 off eBay, anything aftermarket was going to cost me more.