GMC 1998 Yukon - Unlocking the Theft-Deterrent Feature after a Power Loss

Activating the Theft-Deterrent Feature
The instructions which follow explain how to enter your
secret code to activate the
THEFTLOCK system. It is
recommended that you read through all nine steps
before starting the procedure.
NOTE: If yo11 allow more than IS seconds to elapse
between any steps, the radio autolnatically reverts to
time and you must start the procedure over at Step
4.
1.
2.
3.
4.
5.
6.
7.
Write down any three or four-digit number from
000 to 1999 and keep it in a safe place separate from
the vehicle.
Turn the ignition to ACCESSORY or
RUN.
Turn the radio off.
Press the
1 and 4 buttons together. Hold them down
until --- shows on the display. Next you will use the
secret code number which you have written down.
Press
MN and 000 will appear on the display.
Press
MN again to make the last two digits agree
with your code.
Press
HR to make the first one or two digits agree
with your code.
8.
9.
Press AM-FM after you have confirmed that the
code matches the secret code you have written down.
The display
will show REP to let you know that you
need to repeat Steps
5 through 7 to confirm your
secret code.
Press
AM-FM and this time the display will show
SEC to let you know that your radio is secure. The
indicator by the volume control will begin flashing
when the ignition is turned off.
Unlocking the Theft-Deterrent Feature After a
Power
1,oss
Enter your secret code as follows; pause no more than
15 seconds between steps:
1. LOC appears when the ignition is on.
2. Press MN and 000 will appear on the display.
3. Press MN again to make the last two digits agree
with your code.
4. Press HR to make the first one or two digits agree
with your code.
5. Press AM-FM after you have confirmed that the
code matches the secret code you have written down.
The display
will show SEC, indicating the radio is
now operable and secure.
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