2018 CHEVROLET EXPRESS wiring

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
11374212) - 2018 - crc - 2/2/18
Seats and Restraints 67
Adding Equipment to the
Airbag-Equipped Vehicle
Adding accessories that change the
vehicle's frame, bumper system,
height, front end, or side sheet
metal may keep the airbag system
from working properly.
The operation of the airbag system
can also be affected by changing
any parts of the front seats, seat
belts, airbag sensing and diagnostic
module, steering wheel, instrument
panel, inner door seals including the
speakers, any of the airbag
modules, ceiling or pillar garnish
trim, front sensors, or airbag wiring.
Your dealer and the service manual
have information about the location
of the airbag sensors, sensing and
diagnostic module, and airbag
wiring.
If the vehicle has rollover roof-rail
airbags, seeDifferent Size Tires
and Wheels 0273 for additional
important information. If you have to modify your vehicle
because you have a disability and
you have questions about whether
the modifications will affect the
vehicle's airbag system, or if you
have questions about whether the
airbag system will be affected if the
vehicle is modified for any other
reason, call Customer Assistance.
See
Customer Assistance Offices
0 320.
Airbag System Check
The airbag system does not need
regularly scheduled maintenance or
replacement. Make sure the airbag
readiness light is working. See
Airbag Readiness Light 0102.
Caution
If an airbag covering is damaged,
opened, or broken, the airbag
may not work properly. Do not
open or break the airbag
coverings. If there are any
opened or broken airbag
(Continued)
Caution (Continued)
coverings, have the airbag
covering and/or airbag module
replaced. For the location of the
airbags, seeWhere Are the
Airbags? 058. See your dealer
for service.
Replacing Airbag System
Parts after a Crash
{Warning
A crash can damage the airbag
systems in the vehicle.
A damaged airbag system may
not properly protect you and your
passenger(s) in a crash, resulting
in serious injury or even death. To
help make sure the airbag
systems are working properly
after a crash, have them
inspected and any necessary
replacements made as soon as
possible.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
11374212) - 2018 - crc - 2/2/18
102 Instruments and Controls
Voltmeter Gauge
When the engine is not running, but
the ignition is on, this gauge shows
the battery's state of charge in
DC volts.
When the engine is running, the
gauge shows the condition of the
charging system. Readings between
the low and high warning zones
indicate the normal operating range.
Readings in the low warning zone
may occur when a large number of
electrical accessories are operating
in the vehicle and the engine is left
at an idle for an extended period.This condition is normal since the
charging system is not able to
provide full power at engine idle. As
engine speeds are increased, this
condition should correct itself as
higher engine speeds allow the
charging system to create maximum
power.
The vehicle can be only driven for a
short time with the reading in either
warning zone. If it must be driven,
turn off all unnecessary
accessories.
Readings in either warning zone
indicate a possible problem in the
electrical system. Have the vehicle
serviced as soon as possible.
Seat Belt Reminders
Seat Belt Reminder Light
There is a seat belt reminder light
on the instrument cluster.
When the vehicle is started, this
light flashes and a chime may come
on to remind the driver to fasten
their seat belt. Then the light stays
on solid until the belt is buckled.
This cycle may continue several
times if the driver remains or
becomes unbuckled while the
vehicle is moving.
If the driver seat belt is buckled,
neither the light nor the chime
comes on.
Airbag Readiness Light
This light shows if there is an
electrical problem with the airbag
system. The system check includes
the airbag sensor(s), the
pretensioners (if equipped), the
airbag modules, the wiring, and the
crash sensing and diagnostic

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
11374212) - 2018 - crc - 2/2/18
210 Driving and Operating
State and local regulations may also
require the trailer to have its own
braking system if loaded above a
certain threshold. These
requirements vary from state to
state.
Be sure to read and follow the
instructions for the trailer brakes so
they are installed, adjusted, and
maintained properly.
Do not tap into the vehicle's
hydraulic brake system.
Trailer Wiring Harness
The optional heavy-duty trailer
wiring package includes a wiring
harness, with a seven-pin connector
at the rear of the vehicle and a
four-wire harness assembly under
the driver side of the instrument
panel. The four-wire harness
assembly comes without a
connector.
If the vehicle does not have a trailer
hitch, the seven-wire harness
assembly with connector is taped
together and located in a frame
pocket at the driver side rear left
corner of the frame.If the vehicle has a trailer hitch, the
seven-wire harness assembly with
connector is attached to a bracket
on the hitch platform. In both cases,
the seven-wire harness has a
connector and includes a 30-amp
feed wire.
Use only a round, seven-wire
connector with flat blade terminals
meeting SAE J2863 specifications
for proper electrical connectivity.
The seven-wire harness connector
contains the following trailer circuits:
.
Light Green: Back-up Lamps
(10A fuse)**
. White: Ground
. Dark Blue: Trailer Brake Signal
. Dark Green: Right Rear Stop
and Turn Signal*
. Red/Black Stripe: Battery Feed
(30A Fuse)
. Brown: Trailer Park Lamp
Supply Voltage (15A fuse)**
. Yellow: Left Rear Stop and Turn
Signal * The four-wire harness (without
connector) contains the following
circuits:
.
Black: Ground
. Red/White: Battery Feed
. Dark Blue: Trailer Brake Signal
. Light Blue: CHMSL/Stoplamp
Supply Voltage
* 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.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
11374212) - 2018 - crc - 2/2/18
248 Vehicle Care
Electrical System
Electrical System
Overload
The vehicle has fuses and circuit
breakers to protect against an
electrical system overload.
When the current electrical load is
too heavy, the circuit breaker opens
and closes, protecting the circuit
until the current load returns to
normal or the problem is fixed. This
greatly reduces the chance of circuit
overload and fire caused by
electrical problems.
Fuses and circuit breakers protect
power devices in the vehicle.
Replace a bad fuse with a new one
of the identical size and rating.
If there is a problem on the road and
a fuse needs to be replaced, the
same amperage fuse can be
borrowed. Choose some feature of
the vehicle that is not needed to use
and replace it as soon as possible.
Headlamp Wiring
An electrical overload may cause
the lamps to go on and off, or in
some cases to remain off. Have the
headlamp wiring checked right away
if the lamps go on and off or
remain off.
Windshield Wipers
If the wiper motor overheats due to
heavy snow or ice, the windshield
wipers will stop until the motor cools
and will then restart.
Although the circuit is protected
from electrical overload, overload
due to heavy snow or ice may
cause wiper linkage damage.
Always clear ice and heavy snow
from the windshield before using the
windshield wipers.
If the overload is caused by an
electrical problem and not snow or
ice, be sure to get it fixed.
Fuses and Circuit
Breakers
The wiring circuits in the vehicle are
protected from short circuits by a
combination of fuses and circuit
breakers. This greatly reduces the
chance of fires caused by electrical
problems.
Look at the silver-colored band
inside the fuse. If the band is broken
or melted, replace the fuse. Be sure
you replace a bad fuse with a new
one of the identical size and rating.
Engine Compartment
Fuse Block
The fuse block is located in the
engine compartment on the driver
side of the vehicle.
Vehicles with upfitter content
See www.gmupfitter.com for upfitter
provisions and best practices.

Chevrolet Express Owner Manual (GMNA-Localizing-U.S./Canada/Mexico-
11374212) - 2018 - crc - 2/2/18
250 Vehicle Care
FusesUsage
3 Right trailer stoplamp/Turnlamp
4 –
5 –
6 Fuel system control module/Ignition
7 Body control module 5
8 Body control module 7
9 Body control module 4
10 Instrument cluster
11 Trailer wiring
12 –
13 Interior rear vision camera module
14 Windshield washer
16 Horn
17 Transmission
18 A/C Fuses
Usage
19 Engine control module battery
20 Cutaway/Left stoplamp/Turnlamp
21 Left trailer stoplamp/Turnlamp
22 Cutaway/Right stoplamp/Turnlamp
23 –
24 Fuel pump
25 Auxiliary power outlet
26 Body control module 3
27 Special equipment option
28 Airbag
29 Steering wheel sensor
30 Engine control module Ignition Fuses
Usage
31 Transmission control module
Ignition
32 Transmission control module 1
battery/Engine
control module
battery power (gas
6 cyl)
33 Rear parking aid module
34 –
35 –
36 Fuel system control module battery
41 Transmission control 2 module
battery power
42 Trailer wiring
43 –
44 Starter solenoid
45 Engine control module/Powertrain