Chevrolet Silverado 4500HD, Руководство пользователя

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2-12 Fixed and Moveable Windows
A26-K33-X50A Defogger Block Diagram
3511665
Rear Window Defogger Operation
The rear defog control system utilizes a single zone
backlight design, driven with a single relay
configuration. Additionally, up to two outside rear view
mirrors can be heated if required. A switch for the
customer to control the system is provided within the
HVAC controls. Also included in the HVAC controls is
an indicator to inform the customer with the current
state of the system. The system is only operational
when engine is running or during remote start.
Pressing the heated rear window switch causes the
HVAC controls to send a serial data message to the
HVAC control module requesting rear window defog
operation. The HVAC control module upon receipt of
the serial data message will provide voltage to the
coil side of the rear defogger relay, this will energize the
relay causing the relay switch contacts to close
allowing B+ voltage to flow through the rear defogger
grid control circuit to the rear defogger grid.
When the rear heated rear window switch is pressed
and the engine is running, the rear window defogger
grid will activate and will turn off automatically
depending upon the vehicle speed (refer to owner
’ s
manual for rear window defogger operation cycles)
Heated Mirrors
The heated mirrors are also controlled through the rear
defogger relay. Whenever the rear window defogger is
turned on battery voltage is supplied to the mirror
heater elements through the left and right mirror heater
element control circuits.
2021 - Silverado 4500HD, 5500HD, and 6500HD Electrical Body Builder Manual