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Fuses Usage
37 Front Parking Lamps
38 Driver Side Turn Signal
39Heat Ventilation Air
Conditioning 1
40 Truck Body Controller 4
41 Radio
42 Trailer Park
43 Passenger Side Turn Signal
44 Heat Ventilation Air ConditioningFuses Usage
45 Rear Fog Lamps
46 Auxiliary Power 1
47 Ignition 0
48 Four-Wheel Drive
49 Blank
50 Truck Body Controller Ignition
51 Brakes
52 Truck Body Controller Run
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Page 434 of 474

At Least Once a Year
Starter Switch Check
{CAUTION:
When you are doing this inspection, the vehicle
could move suddenly. If the vehicle moves, you or
others could be injured.
1. Before starting this check, be sure there is enough
room around the vehicle.
2. Firmly apply both the parking brake and the regular
brake. SeeParking Brake on page 2-33.
Do not use the accelerator pedal, and be ready to
turn off the engine immediately if it starts.
3. Try to start the engine in each gear. The vehicle
should start only in P (Park) or N (Neutral). If the
vehicle starts in any other position, contact
your dealer/retailer for service.
Automatic Transmission Shift Lock
Control System Check
{CAUTION:
When you are doing this inspection, the vehicle
could move suddenly. If the vehicle moves, you or
others could be injured.
1. Before starting this check, be sure there is enough
room around the vehicle. It should be parked on a
level surface.
2. Firmly apply the parking brake. SeeParking Brake
on page 2-33.
Be ready to apply the regular brake immediately if
the vehicle begins to move.
3. With the engine off, turn the ignition to ON/RUN,
but do not start the engine. Without applying the
regular brake, try to move the shift lever out
of P (Park) with normal effort. If the shift lever
moves out of P (Park), contact your dealer/retailer
for service.
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Page 435 of 474

Ignition Transmission Lock Check
While parked, and with the parking brake set, try to turn
the ignition to LOCK/OFF in each shift lever position.
The ignition should turn to LOCK/OFF only
when the shift lever is in P (Park).
The ignition key should come out only in
LOCK/OFF.
Contact your dealer/retailer if service is required.
Parking Brake and Automatic
Transmission P (Park) Mechanism
Check
{CAUTION:
When you are doing this check, the vehicle could
begin to move. You or others could be injured and
property could be damaged. Make sure there is
room in front of the vehicle in case it begins to roll.
Be ready to apply the regular brake at once
should the vehicle begin to move.Park on a fairly steep hill, with the vehicle facing
downhill. Keeping your foot on the regular brake, set the
parking brake.
To check the parking brake’s holding ability: With the
engine running and the transmission in N (Neutral),
slowly remove foot pressure from the regular brake
pedal. Do this until the vehicle is held by the parking
brake only.
To check the P (Park) mechanism’s holding ability:
With the engine running, shift to P (Park). Then
release the parking brake followed by the regular
brake.
Contact your dealer/retailer if service is required.
Underbody Flushing Service
At least every spring, use plain water to ush any
corrosive materials from the underbody. Take care to
clean thoroughly any areas where mud and other debris
can collect.
Tire Sealant and Compressor Kit
If the vehicle has a Tire Sealant and Compressor
Kit, check the sealant expiration date printed on the
instruction label of the kit at least once a year.
See your dealer/retailer for a replacement canister.
6-11
Page 460 of 474

OnStar®
If your vehicle has OnStar and you subscribe to the
OnStar services, please refer to the OnStar Terms and
Conditions for information on data collection and use.
See alsoOnStar
®System on page 2-43in this manual
for more information.
Navigation System
If your vehicle has a navigation system, use of the system
may result in the storage of destinations, addresses,
telephone numbers, and other trip information. Refer to
the navigation system operating manual for information
on stored data and for deletion instructions.
Radio Frequency
Identi cation (RFID)
RFID technology is used in some vehicles for functions
such as tire pressure monitoring and ignition system
security, as well as in connection with conveniences
such as key fobs for remote door locking/unlocking and
starting, and in-vehicle transmitters for garage door
openers. RFID technology in GM vehicles does not use
or record personal information or link with any other
GM system containing personal information.
7-18
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