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How to Enter the Radio Unlock Code in a GMC

by Dustin Thornton

GM vehicles, including GMC trucks, include a radio theftlock system that allows you to program a radio unlock code into your stereo system. When programmed, the stereo system becomes inoperable if the stereo ever loses power from battery disconnection or stereo removal. This protects the stereo from unauthorized use if stolen. In order to use the GM stereo, once locked, you must enter the radio unlock code successfully using specific buttons on the stereo. It's important to know how to set the radio unlock code for your GMC and to enter it when the radio locks.

Set Radio Unlock Code

Create a three or four digit number that you can use to unlock the radio if the stereo loses power. For example, you may choose a number such as 1289.

Put the key in the ignition and switch the vehicle to "ACCESSORY" or "RUN."

Press the "Power/Volume" knob and turn the radio off, if not already off.

Press and hold the number "1" and "4" preset buttons on the radio simultaneously. Hold until "---" displays on the radio screen.

Press the "MN" button. The numbers "000" will appear on the screen.

Press the "MN" button again, until the last two digits of the numbers on the screen are the last two digits of your three or four digit code. In the example, you would press the "MN" button until the last two digits on screen are "89."

Press the "HR" button until the first one or two digits of the numbers on the screen are the first one or two digits of your three or four digit code. In the example, you would press the "HR" button until the first two digits on the screen are "12."

Press the "AM-FM" button to set the code. "REP" will appear on the screen. Repeat steps 5 through 7 to re-enter your code a second time.

Press the "AM-FM" button once more to confirm the code. "SEC" will appear on the screen. Switch the ignition off.

Unlock Radio

Put the key in the ignition and switch the ignition to "RUN."

Press the "MN" button. The numbers "000" will appear on the screen.

Press the "MN" button again, until the last two digits of the numbers on screen are the last two digits of your three or four digit code. In the example, you would press the "MN" button until the last two digits on screen are "89."

Press the "HR" button until the first one or two digits of the numbers on the screen are the first one or two digits of your three or four digit code. In the example, you would press the "HR" button until the first two digits on the screen are "12."

Press the "AM-FM" button to confirm the code. "SEC" will appear on the screen. Switch the ignition off.

Tips

  • If you take more than 15 seconds to complete any step while creating or enter the radio unlock code, you must start the process over.
  • If your GMC radio flashes "INOP," then you have entered the wrong radio unlock code too many times. Drive the vehicle for one hour or leave the ignition set to the "On" position for one hour to resolve this.

About the Author

Dustin Thornton has been writing since 2003. He has served as a newspaper columnist for the "Troy Tropolitan" and a contributor to various websites. Thornton received a partial scholarship for an outstanding essay in 2003. He has a Bachelor of Science in business administration from Troy University.

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