Wiper/Washer System Components
The Wiper/Washer System consists of the following components:
• | Windshield wiper/washer switch |
• | Body control module (BCM) |
• | Windshield washer nozzles |
• | Windshield washer solvent container |
• | Windshield wiper arm and blade assemblies |
• | Windshield wiper transmission |
Refer to
Wiper/Washer Component Views
.
Wiper/Washer System Description
The body control module (BCM) controls wiper motor low speed operation. The
washer pump and high speed operation are controlled directly by the wiper/washer
switch. The windshield wiper/washer switch supplies voltage on the signal circuits
to the BCM for windshield wiper/washer operation. When WASH, MIST, DELAY, LOW, or
HIGH is detected, the BCM energizes the wiper micro relay by suppling voltage to the
relay coil. This allows battery voltage from the WIPER fuse to flow through the relay
switched input then through the contacts and out the relay switched output to the
wiper 2 relay switch contacts. Since the wiper 2 relay switch contacts
are normally closed to the low speed circuit of the windshield wiper motor, the motor
will operate at low speed.
Wash Operation
In the WASH position windshield wiper/washer switch supplies voltage to the
windshield washer pump. The body control module (BCM) monitors voltage on this circuit
to detect when a wash cycle is requested so it can enable the wipers. After a short
delay, the BCM energizes the wiper relay which will operate the windshield wiper motor
at low speed. The wiper motor will continue to operate for 2 wipe cycles after
the wash switch is released.
Mist Operation
Windshield Wiper/Washer System mist operation is identical to low operation,
except that the mist switch is a press and release type switch. When the wiper switch
is moved to the mist position and released, low speed wiper motor operation is started
and will continue until 1 cycle is complete. If the wiper switch is moved to
the MIST position and held, the wiper motor will operate in the LOW mode until the
switch is released.
In the MIST position, voltage is supplied through an internal resistor to the
signal circuit of the windshield wiper/washer switch for the body control module
(BCM). The BCM will energize the wiper micro relay which will operate the windshield
wiper motor at low speed.
Intermittent Operation
Windshield wiper delay operation is a low speed wiper motor function with a
variable delay interval between the wiper motor cycles. The delay interval is determined
by a series of 5 resistors within the wiper/washer switch. During delay wiper
operation the signal circuit voltage is further reduced through the delay resistors.
The body control module (BCM) monitors the voltage on the signal circuit to determine
the delay interval between the low speed wiper motor cycles.
If the wiper switch is moved from a longer delay interval to a shorter delay
interval, the BCM will command an immediate wipe cycle, and reset the delay timer
to the shorter delay interval.
Low Speed Operation
When the wiper switch is in the Low position, voltage is supplied through an
internal resistor to the signal circuit. The body control module (BCM) monitors the
windshield wiper switch signal 1 circuit, and energizes the wiper micro relay
which will operate the windshield wiper motor. The wiper motor will operate at low
speed, since the wiper 2 relay is de-energized. Low speed can also be commanded
with a scan tool, by commanding Wiper Relay Cmd. ON and OFF. Refer to
Scan Tool Output Controls
.
High Speed Operation
In the High position, the windshield wiper/washer switch supplies voltage to
both the wiper micro relay and wiper 2 relay coils. This energizes both relays
and allows battery voltage from the wiper micro relay switched output to the switched
input of the wiper 2 relay through its contacts and out the switched output
of the wiper 2 relay to the high speed circuit of the windshield wiper motor.
The windshield wiper motor will operate at high speed. During high speed wiper motor
operation the wiper switch signal circuit is at the low speed signal voltage, and
the body control module (BCM) supplies redundant voltage to the wiper relay via the
wiper diode.
Park Position Operation
Windshield wiper motor park operation is controlled by the body control module
(BCM) using an input from the park switch within the wiper motor assembly. The BCM
monitors the windshield wiper motor park switch circuit to determine if the windshield
wiper blades are at the bottom of the glass. The circuit will be pulled to ground
by the wiper motor park switch while the windshield wiper motor is operating. When
the wiper switch is turned to the OFF position while the wiper motor is somewhere
in mid-cycle, the BCM will continue to operate the motor until the wipers reach the
park position. If the ignition is turned OFF while the wipers are in mid-cycle, the
wipers will stop immediately where they are. The BCM will park the wipers the next
time the ignition is turned ON.
The wipers will not park when they are commanded ON and OFF with a scan tool.
The BCM will park the wipers the next time the wiper switch is turned ON and OFF.
The BCM provides stall protection for the wiper motor by monitoring the park
switch. If the park switch does not transition for 3 seconds while the wipers
are operating, the BCM will assume that the wiper motor is stalled, and will de-energize
the wiper relay until the wiper switch is cycled OFF and ON again.
Windshield Wiper/Washer System Power and Ground
With the ignition in the ON position, accessory voltage is supplied through
the WIP/WASH 10A fuse in the underhood fuse block to the wiper/washer switch. Refer
to
Wiper/Washer Schematics
.
G101 provides ground for the following:
Diagnostic Trouble Codes (DTCs)
The body control module (BCM) monitors the voltage on the windshield wiper switch
signal 2 circuit for diagnostic purposes. If the circuit is shorted to voltage
while the driver is commanded OFF, the BCM will store DTC B3717. If the circuit
is shorted to ground while the driver is commanded ON, the BCM will store DTC B3718.