GMC 2008 Sierra 1500 Pickup Owner's Manual page 383

You have two minutes to match the first tire/wheel
position, and five minutes overall to match all four
tire/wheel positions. If it takes longer than two minutes,
to match the first tire and wheel, or more than five
minutes to match all four tire and wheel positions the
matching process stops and you need to start over.
The TPMS sensor matching process is outlined below:
1. Set the parking brake.
2. Turn the ignition switch to ON/RUN with the
engine off.
3. Press the Remote Keyless Entry (RKE) transmitter's
LOCK and UNLOCK buttons at the same time
for approximately five seconds. The horn sounds
twice to signal the receiver is in relearn mode
and TIRE LEARNING ACTIVE message displays
on the DIC screen.
4. Start with the driver side front tire.
5. Remove the valve cap from the valve cap stem.
Activate the TPMS sensor by increasing or
decreasing the tire's air pressure for five seconds,
or until a horn chirp sounds. The horn chirp, which
may take up to 30 seconds to sound, confirms
that the sensor identification code has been
matched to this tire and wheel position.
6. Proceed to the passenger side front tire, and repeat
the procedure in Step 5.
7. Proceed to the passenger side rear tire, and repeat
the procedure in Step 5.
8. Proceed to the driver side rear tire, and repeat the
procedure in Step 5. The horn sounds two times
to indicate the sensor identification code has
been matched to the driver side rear tire, and the
TPMS sensor matching process is no longer active.
The TIRE LEARNING ACTIVE message on the
DIC display screen goes off.
9. Turn the ignition switch to LOCK/OFF.
10. Set all four tires to the recommended air pressure
level as indicated on the Tire and Loading
Information label.
11. Put the valve caps back on the valve stems.
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