Windshield wiper intermittent operation is a low speed wiper motor function with a variable delay interval between the wiper motor
cycles. The duration of the delay is controlled by the front wiper control switches intermittent 1 thru intermittent 5 settings. The
wiper operation is as follows
1. The BCM will initiate a single wipe by activating its front wiper ON/OFF relay output.
2. At the completion of a single wipe, the BCM will park the wipers as described above.
3. The BCM will then pause the wipers in their park position for the time duration associated with intermittent delay switch
setting.
4. When the delay time expires repeat Steps 1 and 3 until the system is turned off or taken out of intermittent mode. 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.
Intermittent wiper operation may be vehicle speed sensitive. When enabled, the speed compensated intermittent feature causes the
intermittent wiper delay intervals to become shorter as a function of increased speed. As vehicle speed is reduced the intervals will
become closer to the predetermined
Windshield Washer System
The BCM controls the windshield wash operation and windshield wash activated wiper operation. When the BCM detects the
activation of the momentary windshield wash control switch, it activates its washer pump relay drive output which supplies battery
power to the coil of the washer pump relay. This energizes the relay, which switches battery power to the pump motor. The BCM will
also activate continuous low speed windshield wipes as described above. Upon deactivation of the windshield wash control switch,
the wiper control module (BCM) shall deactivate the wash motor and will also park the wiper motor as described above unless the
drip wipe feature is enabled. On some vehicles the drip wipe feature will be enabled and cause the system to provide additional
wiping of the windshield after the switch has been released and fluid is no longer being applied. The front wash feature may attempt
to detect a stuck switch. When enabled, activation of the wash feature shall be limited to 10 seconds.
On vehicles with the Rear Wash feature a single reversing wash motor may be utilized for both the front and rear wash operation. In
this system the wash motor is operated in one direction to spray fluid on the front windshield and then operated in the reverse
direction to spray fluid on the rear window. The BCM Controls the reversing wash motor through two High Side Drive outputs. One
controls the Front Wiper Motor Relay and one controls the Rear Wiper Relay.
Rear Wiper System
On vehicles equipped with a Rear Wiper, the BCM determines of the Rear Wipe/Wash System Mode of Operation by monitoring the
multiplexed output of the Rear Wipe/Wash Switch. The Rear Wipe Wash Switch uses a reference ground signal from the BCM. The
BCM provides a switched Battery pull-up for the Rear Wiper/Washer Switch output signal it receives. All the BCM inputs are
recognized as active when the Rear Wiper Switch provides a path to the referenced ground signal. The Rear Wiper/Washer signal
received by the BCM is the result of 3 resistors in the Rear Wiper Switch configured as a resistor ladder network. This signal is
connected to a BCM Analog to Digital Input which also provides a switched Battery pull-up for the circuit. Depending on the function
selected (Low, Intermittent, Off, Wash), the Rear Wiper Control Switch connects a different set of resistors into the circuit resulting
in different voltages appearing on the BCM A/D input. By monitoring this voltage, the BCM determines how to control the Rear Wiper
Motor Relay and the Rear Washer Relay.
The BCM Controls the single speed Rear Wiper Motor by its Active High output to the external Rear Wiper Motor Relay. When the
BCM activates its output and applies Battery to the coil of the relay, the relay energizes, allowing Battery voltage from the fuse to be
applied through the switched contacts of the Rear Wiper Motor Relay to the Rear Wiper Motors control input. The motor then
operates continuously at low speed. The BCM does not control the parking of the Rear Wiper Motor, it is self parking. When the BCM
deactivates its output, the contacts of the Rear Wiper Motor Relay switch back to ground which will be used by the wiper for
Dynamic Braking. The Rear Wipers internal park switch and circuitry will sustain motor operation until the wiper arm has returned to
its Park position.
Rear Wash
When the Body Control Module detects that the Rear wiper/wash switch has activated the momentary Wash switch, it activates a
High Side Drive output which supplies Battery to the coil of the Rear Washer Pump Relay. This energizes the Relay, which switches
Battery Power to the Washer Pump Motor. The BCM will also activate continuous Low Speed Windshield Wipers as described above.
The BCM software will attempt to detect a stuck Rear Wash Switch. A stuck Rear Wash Switch condition is detected if the Rear Wash
Motor Relay Output has been continuously active for 10 seconds or more. Upon detecting this the BCM will fail soft the state of the
Rear Wash Control to Inactive. This shall cause the System to perform as if the momentary Wash control had been released.
© 2011 General Motors. All rights reserved.
Wipers and Washers
BODY SYSTEMS
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CHEVROLET SONIC 2012 BODY REPAIR MANUAL
