Q:The battery started dying in my 1997 VW Jetta, so a friend helped me replace it. Now my radio does not work. It says "SAFE" where the station display is. I bought this car used and do not have a manual for the radio. Can you tell me how to make it play? -Pamela B., Minneapolis

A:This is an anti-theft feature many manufacturers have implemented (Volkswagens say SAFE; others may simply cease working or display other characters). The theory is as soon as a few thieves steal them and whoever they pawn them to can't make these radios work, the motivation to steal radios from these manufacturers disappears.

Radios that quit once the battery has been disconnected generally require that you punch in a code specific to that radio - the code from your neighbor's radio in the same make and model of car won't work. You've said you don't have the owner's documentation, so you may need to take your car to a dealership, whose mechanics can check out the serial number on the radio, look up the code and reset it. If the car came from a local dealership and was dealer-maintained, they may have a file on it with the code written down if they replaced the battery.

There may be a shortcut. Sometimes there is a sticker that includes the code tucked away somewhere on the car. The dealership we bought our '96 VW Golf from placed a sticker underneath the carpet in the trunk with the code written on it. I have heard of Hondas with such a sticker in the glovebox. They can also be stuck on the back of the ashtray or in other out of the way places. Take a few minutes and look around for a sticker with a four-digit code on it. (With another manufacturer, this code may be five digits or some other length.)

The procedure for your Volkswagen should be as follows. With other manufacturers it may involve different buttons.

1.Put the key in the ignition to send power to the radio. "SAFE" appears.

2.Press the Mode and Scan buttons simultaneously and hold. The number 1000 will appear where SAFE used to be.

3.Using radio preset buttons one through four, enter your radio code. If your radio is like ours, and the first code digit is zero, leave it blank if pressing preset button one generates only a 1 or a blank space.

4.Using preset buttons two through four, enter the remaining digits of your radio code.

5.Finally, press and hold the Mode and Scan buttons simultaneously until the word SAFE appears again. Release the buttons. In a few seconds, the old familiar station frequency you saw before your battery change will reappear.

Readers with this problem from another manufacturer, try the following. First, look at your owners documentation. If the radio booklet is there, the code is probably shown on the front or inside cover. The booklet or your owner's manual should explain the reset procedure. If you don't have the documentation, try a few Internet searches, such as "reset radio [make] [model]" or "disconnect battery radio [make] [model]." Once you know the procedure, you'll still need your radio's code. A dealership can reset it but they'll need your radio's (not the vehicle's) serial number and they may charge you for this service.

If you ever need to disconnect or replace your battery again, here's a trick: connect jumper cables from another car's battery to your car's battery leads. Remove your old battery and swap in the new one without disconnecting the jumper cables. When your new battery is connected to the leads, then disconnect the cables and your radio will never have lost power and won't go into anti-theft mode.