Chevy Impala Radio THEFTLOCKED

JimG · July 1, 2005

Hi,

My dad owns a 2002 Chevy Impala with 70k+ miles on it. Never had a major problem with it until recently. What's happening is, at random, when he starts the car, the radio goes into THEFTLOCK mode. It'll do this for several ignition cycles, then just come up fine on another cycle. Now, just to clear up the obvious stuff:

1. My dad's no mechanic or electrician. That radio has never been removed by him and no part of the car has been upgraded or modified since he bought it. He makes sure it gets regular maintenance of course, but I doubt he knows where the oil filter is ...

2. The clock/radio presets/etc, are always right. I don't think it's losing the constant +12V because at least 1 of the radio settings, generally the clock, should reset to 12:00, correct? If the radio does lose the constant +12V, doesn't it automatically go into THEFTLOCK mode when the power is applied?

So, is there anything I can look for or check with my meter or does this require a trip to the dealer? And based on the symptoms I'm describing, would it be the radio itself that has a problem? I don't want my dad to pay for a new radio, I priced it out on GMPartsdirect and it comes out to $680.92 (list price). If it helps, he has the AM/FM/CD radio. At that point, I'd think it would be cheaper and more effective to just get an aftermarket head unit and replace the stock unit.

Thanks for your help!

Edit - I probably should add that the battery/charging system is fine - no loss of power there; that was checked as soon as the problem started.

GM-Tech · July 1, 2005

At that point, I'd think it would be cheaper and more effective to just get an aftermarket head unit and replace the stock unit.

No, I think it would be easier to just remove the code so theftlock is disabled. End of problem.

As to why it's happening... I have not seen a radio have this problem without a loss of voltage, but with electronics, anything is possible. So it could be the radio itself, though that is unlikely. I also think that if voltage was lost, the clock should reset, though a momentary loss probably wouldn't cause the presets to be lost.

Disable the theftlock and see if it reoccurs. If he never put a code in the radio, did he buy the car used? If so, the previous owner probably did. To date, I have not seen one person that can remember the code they used and many say they never put a code in... but one is there.

JimG · July 1, 2005

No, I think it would be easier to just remove the code so theftlock is disabled. End of problem.

This can be done?? Oh cool, I had no idea. I thought once enabled, that was it ... could never be disabled.

He bought the car brand new off the dealer lot - no previous owner. He's not exactly electronics-savy so I doubt he ever entered a code; although pushing buttons in the right order yields amazing results. But yeah, he's one of those swears he never put a code in.

I had no idea you could just disable the theftlock. I'll tell him he needs to have the dealership do this.

Thanks so much for the help!!!

Edit - Sorry, thought of this after I wrote my reply:

Is it possible for the service tech to see if a password/code exists on that radio prior to clearing it? Sort of like with PC's - I can see if a user has a password, not the real password, but I'll know if one exists or not. Only reason I'm asking is because if he (my dad) truly never set the code, then the Theftlock feature should be disabled ... I'm just thinking a slim chance there's something internally wrong with the radio. I know my 03 Sierra's radio had a really strange issue that required replacement. I know the idea's a little far out, but like you said, this is electronics ...

GM-Tech · July 1, 2005

Hmmm, my information is telling me that radio is a VIN learning type of radio. Which means, no code needs to be input nor can one be input. I didn't think we had that in '02, but that's right around the time things were changing so I guess yours does.

In which case it means it's probably losing communication with the body control module, and BCM's on the Impala are known for their high failure rate. So it could be a BCM problem, a radio problem, or a wiring issue. Maybe putting in an aftermarket radio might be the cheaper solution.

JimG · July 4, 2005

Well, he (my dad) has an appt on Jul 11 with the Chevy dealer where he bought the car. He's going to ask about disabling theftlock or whatever they can do.

I thought that started on the 03 model years - didn't know it was one of those "smart" radios ...

As for the BCM on the Impala - ouch, that's not good. I didn't know they had a high failure rate.

If you want, I'll post back after the 11th with the results from the dealer.

As always, thanks for the help!

GM-Tech · July 4, 2005

I thought that started on the 03 model years - didn't know it was one of those "smart" radios ...

I didn't think that the '02 had that either, but that's what our service information says. Depended on the model too. If he does have that, it cannot be disabled.

blue2kzr2 · July 5, 2005

At that point, I'd think it would be cheaper and more effective to just get an aftermarket head unit and replace the stock unit.

No, I think it would be easier to just remove the code so theftlock is disabled. End of problem.

As to why it's happening... I have not seen a radio have this problem without a loss of voltage, but with electronics, anything is possible. So it could be the radio itself, though that is unlikely. I also think that if voltage was lost, the clock should reset, though a momentary loss probably wouldn't cause the presets to be lost.

Disable the theftlock and see if it reoccurs. If he never put a code in the radio, did he buy the car used? If so, the previous owner probably did. To date, I have not seen one person that can remember the code they used and many say they never put a code in... but one is there.

<{POST_SNAPBACK}>

I've had the radio in my 2000 S-10 disconnected overnight, all I lost was the time. The presets must be saved in some sort of solid-state memory, not volatile memory.

JimG · July 5, 2005

blue2kzr2

Thanks - good point. I feel like a dumb a$$ now because I realized my truck does the same thing. Presets are always there but the time's not. Thanks!

GM-Tech

If I'm being a PITA asking questions, let me know ... but this is something I thought of today at work (slow day...)

BCM's on the Impala are known for their high failure rate

I was searching on this ... came up with this from GM Techlink:

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This information applies to the Motorola BCMs used in several GM vehicle lines:

- Chevrolet Impala/Monte Carlo

- Pontiac Aztek/Buick Rendezvous

- Chevrolet Equinox

TIP: A microprocessor condition that affected early BCMs was corrected during the 2003 model year, beginning with p/n GMAN169 (Impala/Monte Carlo) and GMAN410C (Aztek/Rendezvous). Any BCM with a higher part number contains the microprocessor improvement. The Equinox, a newer vehicle, never had the earlier microprocessor.

Based on the history of these earlier control modules, technicians consider BCM replacement as the appropriate remedy for a number of customer concerns and vehicle conditions. However, with the improved microprocessor, this is not often the case. Analysis shows that almost 75% of BCMs replaced under warranty have no trouble found (NTF).

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Would this be the solution to the high failure rate? Also, just curious: What problems have you seen or know of related to the Impala BCM? If you can't elaborate or if I'm delving too deep into something I shouldn't, just say so because I'm not sure ... I'm wondering if this problem will be the first of many issues with the BCM he has in the Impala now and if a new one will cure all ills (now and in the future). Therefore cheaper to replace the BCM now then after many visits to the dealer, diagnostic fees, etc.

As always, thanks for the help! I appreciate it!

GM-Tech · July 6, 2005

The BCM performs a LOT of functions and the symptoms we see are varied. All sorts of bizzare things can happen.

JimG · July 13, 2005

Well, he took it to the dealership. Service guy said the radio was "throwing many codes" when they went to diagnose it and that it was the source of his problems. Recently, it stopped reading CDs also - that was after July 5. They told him the new radio would be $475 (for the part, not the labor) and recommended he have it fixed elsewhere. Kudos to the dealership!

So now I'll be installing a nice Pioneer head unit.