I NEED unlock codeTO UNLOCK MY STERO IN A 2004 TAHOE can some one please help me
There is no actual "security code" in the radio as in past model years. The newer theft deterrent system utilizes the class 2 serial data to determine if the radio is in the appropriate vehicle...in other words it compares the VIN it has stored in it's memory with the VIN of the other modules (body control and PCM) in the vehicle to "check" to see that it's in the correct vehicle.
Each time the radio receives the "run" power mode message, it compares the VIN information it has stored to the VIN information received from a module on the class 2 serial data circuit responsible for transmitting that information. If a mis-match occurs, the radio display will indicate to the user the radio is locked. Once this takes place the radio will not respond to any buttons/commands and becomes inoperative. But the dealer can reestablish the radio into a different vehicle with a scanner.
There are 2 types of GM Theftlock, Theftlock I and Theftlock II. The Theftlock I is found in pre 2000 vehicles, and Theftlock II is in the later models.
Theftlock I - Uses a volatile user settable code that is input through the key pad on the front of the Radio. If the power is lost (dead battery etc.) the code is gone and must be re-entered for the radio to work. But with the correct procedure the owner can unlock it.
Theftlock II - Uses an EPROM (erasable/programmable read only memory) or a PROM (the difference is you can not alter the prom once it is programmed).
In either case the code is burned in and holds even when the power is lost. With Theftlock II the radio is married to the vehicle by way of the VIN. When the vehicle is started the computer compares the number in the radio with the VIN in the body control module. If they match, the radio works, if not the radio displays LOC and you are finished, there is no easy way around it. The radio will not work until you make a trip to the dealer.
The dealer will use a TECH 2 scanner to change the VIN stored in the radio. The radio does not need to be removed (for the serial number or any other nonsense). The technician just plugs into the computer and resets the VIN in the radio.
Thank you for using fixya and good luck. you might get luck by removing the fuse toy our radio for 5 min and reinstalling it, this will reset the radio to default and all you need to do is reset the clock and radio presets.
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