Chevrolet Low Cab Forward 4500 2019 Series Owner's Manual page 175

174 Driving and Operating
Driving in sand or mud, or on a
muddy road may adversely affect
the brakes and ABS sensors.Wash
the vehicle to remove sand and mud
after operating the vehicle in sandy
or muddy conditions.
Before washing the vehicle, provide
necessary protection to prevent
water from being splashed on the
ABS components (sensors and
actuators). Especially when using
high-pressure washing, be careful
not to allow water to be directly
sprayed onto the ABS components
or their harness connectors.
These are not signs of ABS
malfunction:
Soon after you start the engine,
the sound of the valves working
may be heard from the rear of
the vehicle or underside of the
cab. This sound is from a
self-check by the ABS system
and is normal.
When ABS is properly operating,
vibration is felt on the steering
wheel and/or a mechanical
operating sound is heard.
ABS is more likely to activate
when the brakes are applied
during cornering or driving over
a bump. This is because wheels
that have gone over a bump
would tend to lock due to loss of
contact with the ground.
ABS is not activated immediately
after starting the vehicle. It is
activated only when the vehicle
speed reaches approx. 10 km/h
(6 MPH). ABS operation is
inactive when the vehicle speed
reduces to approx. 5 km/h
(3 MPH).
ABS Operation Indications and
Signs
ABS warning light
Operation Indications of ABS
When the engine control switch is
placed into the "ON" position, the
ABS warning light comes on and
then goes out in approx. 3 seconds.
The ABS is normal if the warning
light goes out.
Operation Signs of ABS
When ABS is activated, slight
vibration is transmitted to the brake
pedal (hydraulic brake model) and
steering wheel, and an operating
sound can be heard from the ABS
components.
If the ABS warning light does any of
the following, the ABS may be
faulty. Please contact the nearest
dealer.