How to Reset a GM Radio

by Steve Brachmann
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While performing maintenance on your car, you may disconnect the radio from the battery in your GM vehicle. GM cars contain Delco radios that are protected by Theftlock, which locks the radio after it has been disconnected from a power source. Iit can only be reset and unlocked with a car-specific security code. Identifying the security code for your GM vehicle is the only way to reset the car radio and disable the Theftlock protection device.

Step 1

Turn on your car. Your Delco radio will show “LOC” in the LED display.

Step 2

Press and hold down both the second and third preset buttons. Hold these buttons down for at least six seconds.

Step 3

Write down the two- or three-digit code that appears in the LED display.

Step 4

Press the AM/FM button on the radio.

Step 5

Write down the next two- or three-digit code that appears in the LED display. You should be left with either a four- or six-digit number. Turn off your car.

Step 6

Call the Delco radio automated customer support line at 1-800-537-5140.

Step 7

Press “1” and then press the pound sign. The automated voice should respond “Invalid code, try again.”

Step 8

Enter the number 139010 into your phone and then press the “*” sign.

Step 9

Enter the four- or six-digit number you wrote down from Steps 3 and 5, and then press the “*” button.

Step 10

Write down the four-digit code given by the automated voice.

Step 11

Turn on your car. Enter the Delco unlock code using the procedure outlined by your GM owner’s manual. Normally, the unlock code is entered with the “HR” and “MN” buttons on your radio.

Step 12

Press the AM/FM button. If you have entered the code correctly, your LED display will read “SEC” and the radio will be unlocked.

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