2021 CHEVROLET EXPRESS CARGO light

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
174 Driving and Operating
The seven-wire harness contains the
following trailer circuits:Stop/Turn
Signal Left* Yellow
Stop/Turn Signal
Right* Dark Green
Tail/Parking
Lamps** Brown
Reverse Lamps** Light Green
Battery Feed Red/Black
Ground White
Electric Trailer Brake Dark Blue
*If the vehicle is a cutaway with trailer
provisions, a 15 amp fuse will be shared
for both left/stop trailer turn and right/
stop trailer turn signals. However, the
cutaway lighting connector will have a
10 amp fuse for each signal.
**If the vehicle is a cutaway with trailer
provisions, a 15 amp fuse will be shared
for trailer park lamps and cutaway rear
lighting connector park lamps. Also, a
10 amp fuse will be shared for trailer
back-up lamps and cutaway rear lighting
connector back-up lamps. Heavy-Duty Trailer Wiring Harness Package
lf equipped, the trailer wiring harness, with
a seven-pin connector is mounted on the
trailer hitch.
1. Left Turn/Brake
2. Taillamps
3. Reverse Lamps
4. Battery Feed
5. Right Turn/Brake
6. Electric Brakes
7. Ground
Electric Brake Control Wiring Provisions
If the vehicle is not equipped with an
integrated trailer brake controller, and the
trailer has electric brakes, a trailer brake
controller needs to be installed on the
vehicle. The brake controller should be
installed by your dealer or a qualified
service center.
If equipped, wiring provisions for an
aftermarket electric trailer brake controller
are included with the vehicle as part of the
trailer wiring package. The harness contains
the following circuits:
Electric Trailer
Brakes Dark Blue
Battery Feed Red/White
Brake Apply Signal Light Blue
Ground Black
There are four blunt cut wires under the
floor carpeting in front of the brake pedal.
It will be necessary to have a technician
connect the 12-volt power to the engine
compartment fuse block.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
Driving and Operating 175
Refer to the aftermarket electric trailer brake
controller owner's manual to determine wire
color coding of the electric trailer brake
controller. The wire colors on the brake
controller may be different from the vehicle.
Trailer Lamps
Always check all trailer lamps are working at
the beginning of each trip, and periodically
on longer trips.
Turn Signals When Towing a Trailer
When properly connected, the trailer turn
signals will illuminate to indicate the vehicle
is turning, changing lanes, or stopping.
When towing a trailer, the arrows on the
instrument cluster will illuminate even if the
trailer is not properly connected or the bulbs
are burned out.
Tow/Haul Mode
Tow/Haul assists when pulling a heavy
trailer or a large or heavy load. For
instructions on how to enter Tow/Haul
mode, seeTow/Haul Mode 0145.
Tow/Haul Mode is designed to be most
effective when the vehicle and trailer
combined weight is at least 75% of the vehicle's Gross Combined Weight Rating
(GCWR). See
“Trailer Weight” underTrailer
Towing 0164.
Tow/Haul Mode is most useful when towing
a heavy trailer or carrying a large or
heavy load:
.through rolling terrain
.in stop-and-go traffic
.in busy parking lots
Operating the vehicle in Tow/Haul Mode
when lightly loaded or not towing will not
cause damage; however, it is not
recommended and may result in unpleasant
engine and transmission driving
characteristics and reduced fuel economy.
Trailer Sway Control (TSC)
Vehicles with StabiliTrak/Electronic Stability
Control (ESC) have a Trailer Sway Control
(TSC) feature. Trailer sway is unintended
side-to-side motion of a trailer while towing.
If the vehicle is towing a trailer and the TSC
detects that sway is increasing, the vehicle
brakes are selectively applied at each wheel,
to help reduce excessive trailer sway.
If TSC is enabled, the Traction Control
System (TCS)/StabiliTrak/ESC warning light
will flash on the instrument cluster. Reduce
vehicle speed by gradually removing your
foot from the accelerator. If trailer sway
continues, StabiliTrak/ESC can reduce engine
torque to help slow the vehicle. TSC will not
function if StabiliTrak/ESC is turned off. See
Traction Control/Electronic Stability Control
0 147.
{Warning
Trailer sway can result in a crash and in
serious injury or death, even if the
vehicle is equipped with TSC.
If the trailer begins to sway, reduce
vehicle speed by gradually removing your
foot from the accelerator. Then pull over
to check the trailer and vehicle to help
correct possible causes, including an
improperly or overloaded trailer,
(Continued)

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
176 Driving and Operating
Warning (Continued)
unrestrained cargo, improper trailer hitch
configuration, or improperly inflated or
incorrect vehicle or trailer tires. See
Towing Equipment0172 for trailer
ratings and hitch setup recommendations.
Trailer Tires
Special Trailer (ST) tires differ from vehicle
tires. Trailer tires are designed with stiff
sidewalls to help prevent sway and to
support heavy loads. These features can
make it difficult to determine if the trailer
tire pressures are low only based on a visual
inspection.
Always check all trailer tire pressures before
each trip when the tires are cool. Low trailer
tire pressure is a leading cause of trailer tire
blow-outs.
Trailer tires deteriorate over time. The trailer
tire sidewall will show the week and year
the tire was manufactured. Many trailer tire
manufacturers recommend replacing tires
more than six years old. Overloading is another leading cause of
trailer tire blow-outs. Never load your trailer
with more weight than the tires are
designed to support. The load rating is
located on the trailer tire sidewall.
Always know the maximum speed rating for
the trailer tires before driving. This may be
significantly lower than the vehicle tire
speed rating. The speed rating may be on
the trailer tire sidewall. If the speed rating is
not shown, the default trailer tire speed
rating is 105 km/h (65 mph).
Conversions and Add-Ons
Add-On Electrical Equipment
{Warning
The Data Link Connector (DLC) is used for
vehicle service and Emission Inspection/
Maintenance testing. See
Malfunction
Indicator Lamp (Check Engine Light) 076.
A device connected to the DLC —such as
an aftermarket fleet or driver-behavior
tracking device —may interfere with
vehicle systems. This could affect vehicle (Continued)
Warning (Continued)
operation and cause a crash. Such devices
may also access information stored in the
vehicle’s systems.
Caution
Some electrical equipment can damage
the vehicle or cause components to not
work and would not be covered by the
vehicle warranty. Always check with your
dealer before adding electrical equipment.
Add-on equipment can drain the vehicle's
12-volt battery, even if the vehicle is not
operating.
The vehicle has an airbag system. Before
attempting to add anything electrical to the
vehicle, see Servicing the Airbag-Equipped
Vehicle 044 and
Adding Equipment to the Airbag-Equipped
Vehicle 045.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
Vehicle Care 187
How to Check Automatic Transmission
Fluid
Because this operation can be difficult, it is
recommended to have this check done at
your dealer, which can monitor the
transmission temperature. The transmission
fluid level increases with temperature. To
obtain a highly accurate fluid level check,
the transmission temperature must be
measured.
If it is decided to check the fluid level, be
sure to follow all the instructions here, or a
false reading on the dipstick may occur.
Caution
Too much or too little fluid can damage
the transmission. Too much can mean
that some of the fluid could come out
and fall on hot engine parts or exhaust
system parts, starting a fire. Too little
fluid could cause the transmission to
overheat. Be sure to get an accurate
reading if checking the transmission fluid.Wait at least 30 minutes with the engine
off, before checking the transmission fluid
level if the vehicle has been driven:
.In hot weather, when outside
temperatures are above 32 °C (90 °F).
.The vehicle is heavily loaded.
.At high speed for quite a while in hot
weather.
.In heavy traffic and hot weather.
.While pulling a trailer.
After driving under these conditions, a hot
check can be performed. The fluid should be
hot, which is 71 °C to 93 °C (160 °F to
200 °F).
A cold fluid level check can be performed
after the vehicle has been sitting for eight
hours or more with the engine off, but this
is used only as a reference. Let the engine
run at idle for five minutes if the outside
temperature is between 15 °C to 32 °C (60 °F
to 90 °F). Should the fluid level be low
during this cold check, the fluid must be
checked warm or hot before adding fluid.
If the outside temperature is colder than
15 °C (60 °F) or hotter than 32 °C (90 °F), a
cold check cannot be performed. A warm fluid level check can be performed
by driving the vehicle under lightly loaded
conditions and outside temperatures
between 10 °C to 27 °C (50 °F to 80 °F). The
vehicle should be driven for at least 24 km
(15 mi) before performing a warm check.
Checking the fluid warm or hot will give a
more accurate reading of the fluid level than
a cold check.
Because the vehicle is equipped with a
high-efficiency air-to-oil cooler, the
transmission fluid temperature may not
reach the required hot fluid level checking
temperature under normal lightly loaded
driving vehicle conditions.
Checking the Fluid Level
Prepare the vehicle:
1. Park the vehicle on a level place. Keep the engine running.
2. With the parking brake applied, place the shift lever in P (Park).
3. With a foot on the brake pedal, move the shift lever through each gear range,
pausing for about three seconds in each
range. When M is reached, move the
selector from M1 through M3. Then,
position the shift lever in P (Park).

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
198 Vehicle Care
There are only two reasons why the brake
fluid level in the reservoir may go down:
.Normal brake lining wear. When new
linings are installed, the fluid level goes
back up.
.A fluid leak in the brake hydraulic system.
Have the brake hydraulic system fixed.
With a leak, the brakes will not
work well.
Always clean the brake fluid reservoir cap
and the area around the cap before
removing it.
Do not top off the brake fluid. Adding fluid
does not correct a leak. If fluid is added
when the linings are worn, there will be too
much fluid when new brake linings are
installed. Add or remove fluid, as necessary,
only when work is done on the brake
hydraulic system.
{Warning
If too much brake fluid is added, it can
spill on the engine and burn, if the
engine is hot enough. You or others could
be burned, and the vehicle could be
damaged. Add brake fluid only when
work is done on the brake hydraulic
system. When the brake fluid falls to a low level,
the brake warning light comes on. See
Brake
System Warning Light 077.
Brake fluid absorbs water over time. Replace
brake fluid at the specified intervals to
prevent increased stopping distance. See
Maintenance Schedule 0251.
Checking Brake Fluid
Check brake fluid by looking at the brake
fluid reservoir. See Engine Compartment
Overview 0181.
The fluid level should be above MIN. If it is
not, have the brake hydraulic system
checked to see if there is a leak. After work is done on the brake hydraulic
system, make sure the level is above MIN
but not over the MAX mark.
What to Add
Use only GM approved DOT 3 brake fluid
from a clean, sealed container. See
Recommended Fluids and Lubricants
0257.
{Warning
The wrong or contaminated brake fluid
could result in damage to the brake
system. This could result in the loss of
braking leading to a possible injury.
Always use the proper GM approved
brake fluid.
Caution
If brake fluid is spilled on the vehicle's
painted surfaces, the paint finish can be
damaged. Immediately wash off any
painted surface.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
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Vehicle Care 203
To replace the front turn signal, sidemarker,
and/or parking lamp bulb(s):
1. Use a small tool to unlatch the outboardclip on the lamp by pushing inboard and
prying the lamp assembly forward.
2. Remove the lamp from the grille.
3. Turn the bulb socket counterclockwise one-quarter turn and remove it from the
lamp assembly.
4. Remove the bulb from the socket by pulling it straight out.
5. Replace the bulb.
6. Turn the bulb socket clockwise to reinstall it in the lamp assembly.
7. Reinstall the lamp assembly into the grille until the outboard clip snaps into
place.
Taillamps
To replace a taillamp/turn signal lamp or
back-up lamp bulb:
1. Remove the two inboard nuts from theinside of the taillamp assembly.
2. The third nut (3) is under the appliquepiece (2) above the lamp. Remove the
two inboard applique nuts. Pull the
applique (2) straight rearward slightly to
clear the studs. Then rotate the
applique (2) just far enough to gain
access to the outer push pins (1).
3. Carefully disconnect the push pins (1) from the applique bracket.
4. Remove the third nut (3) from the upper outboard side of the lamp.
5. Remove the taillamp assembly from the vehicle.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
Vehicle Care 209
FusesUsage
68 Auxiliary stoplamps
69 External power for trailer
70 Upfitter stoplamps 71 Fuel heater/FlexFuel sensor
72 Body control module 6
73 Lighter/Data link connector
74 Front blower 75 Engine control module
76 Soot sensors (Diesel only)
77 O2 sensor 1
78 Engine control module/ Powertrain signal 1
79 Ignition coils/injectors - even Relays
Usage
15 Run/Crank
37 NOX Sensor (Diesel only)
38 Fuel pump
39 Crank
40 A/C compressor 48 Electro viscous fan clutch (Diesel only)
49 Powertrain 50 –
57 –
60 – Auxiliary Fuse Block
This component is near the fuse block in the
engine compartment
Fuses Usage
MR-1 Upfitter 1
MR-2 Upfitter 2
MR-3 Upfitter power control
Relays Usage
MR Rel 1 Upfitter 1
MR Rel 2 Upfitter 2

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
14583525) - 2021 - CRC - 12/9/20
Vehicle Care 213
Winter Tires
This vehicle was not originally equipped
with winter tires. Winter tires are designed
for increased traction on snow and
ice-covered roads. Consider installing winter
tires on the vehicle if frequent driving on ice
or snow covered roads is expected. See your
dealer for details regarding winter tire
availability and proper tire selection. Also,
seeBuying New Tires 0223.
With winter tires, there may be decreased
dry road traction, increased road noise, and
shorter tread life. After changing to winter
tires, be alert for changes in vehicle
handling and braking.
If using winter tires:
.Use tires of the same brand and tread
type on all four wheel positions.
.Use only radial ply tires of the same size,
load range, and speed rating as the
original equipment tires.
Winter tires with the same speed rating as
the original equipment tires may not be
available for H, V, W, Y, and ZR speed rated
tires. If winter tires with a lower speed
rating are chosen, never exceed the tire's
maximum speed capability.
Tire Sidewall Labeling
Useful information about a tire is
molded into the sidewall. The example
shows a typical light truck tire sidewall.
Light Truck (LT-Metric) Tire
(1) Tire Size:The tire size code is a
combination of letters and numbers
used to define a particular tire's width,
height, aspect ratio, construction type,
and service description. See the “Tire
Size” illustration later in this section for
more detail. (2) TPC Spec (Tire Performance Criteria
Specification)
:Original equipment tires
designed to GM's specific tire
performance criteria have a TPC
specification code molded onto the
sidewall. GM's TPC specifications meet
or exceed all federal safety guidelines.
(3) Dual Tire Maximum Load
:
Maximum load that can be carried and
the maximum pressure needed to
support that load when used in a dual
configuration. For information on
recommended tire pressure see Tire
Pressure 0217 and
Vehicle Load Limits 0132.
(4) DOT (Department of
Transportation)
:The Department of
Transportation (DOT) code indicates that
the tire is in compliance with the U.S.
Department of Transportation Motor
Vehicle Safety Standards.
DOT Tire Date of Manufacture
:The last
four digits of the TIN indicate the tire
manufactured date. The first two digits
represent the week (01-52) and the last
two digits, the year. For example, the