Windshield Wiper System
On Wiper System Smart equipped vehicles, the body control module (BCM) will command front wiper operations via local interconnect network (LIN) serial data communications instead of via ON/OFF and HIGH/LOW Wiper Motor Relay Drive Outputs. In front wiper systems using the Wiper System Smart - Single configuration, the Driver's side and Passenger's side Wiper Arm are connected by a mechanical linkage with a single integrated Front Wiper Motor/Controller operating them. The Front Wiper Motor/Controller contains the necessary electronics, motor, and position sensors to execute front wiper commands from the Body Control Module. These internal electronics are integrated into the cover of the wiper motor gear housing and are not considered a serviceable item. The Front Wiper Motor/Controller wipes the front windshield by controlling the up and down wiper arm movement by the use of a reversing motor and an internal position sensor. The sensor keeps track of the gear wheel position and when the Controller determines that the wiper arms are at a position to reverse direction, it reverses the motor supply voltage by use of its internal motor control circuitry. The interface between the BCM and the Front Wiper Motor/Controller utilizes a Master/Slave configuration using a LIN serial data system for communication. The BCM is designated as the master, and the Front Wiper Motor/Controller is configured as the slave. As the System Master, the BCM uses the LIN communication bus to command Front Wiper operation, and communicate vehicle information to the Wiper Motor controller. The Front Wiper Motor/Controller provides system status and diagnostic information to the BCM for diagnostic reporting and operational purposes. The Body Control Module (BCM) also provides a hardwired redundant output that switches Battery power to the Wiper Motor upon activation of its low assertion High Speed Wiper Switch input. The BCM will do this, even if the module has lost all microprocessor control. The Front Wiper Motor/Controller gives priority to its LIN input over this Redundant Control Input, however, in the event that LIN communications are lost between the BCM and the Front Wiper Motor/Controller this redundant signal is used to command the required fail-soft wiper actions including Power Mode. While under Redundant Input control the Front Wiper Motor/Controller shall provide Continuous Low Speed Wiper operation when the input is Active, and will park the Wipers and go to Low Power Mode when the Redundant Input is Inactive.
While the Front Wiper Switch is either held in the MIST position (momentary contact switch) or is in its LOW position (latching switch), the BCM provides continuous Low Speed Wiper operation by commanding uninterrupted Low Speed Wiper operation by setting the transmitted LIN signal to Low Speed Wipe.
The BCM shall command the Wiper System Smart to perform Intermittent Wipes as follows:
- Perform one immediate wipe by issuing a LIN signal set to Low Wipes. The Front Wiper Motor/Controller shall initiate Low Speed Wiper Operation and send a LIN signal back set to Low Wiping.
- Upon the wipers leaving their PARKED position, the Front Wiper Motor/Controller shall send a LIN signal indicating the wipers are no longer in park.
- Upon receipt of the Wiper out of Park LIN signal, the BCM shall transition the Front Wiper Command LIN signal to Park. While the wiper system smart is in the process of moving the wipers to their parked position, it shall set the value of its Wiper Front Status LIN signal to Parking.
- The current wipe cycle will be completed and the wipers parked. Upon parking the wipers, the wiper system smart sends the Wiper Front Status LIN signal set to Parked.
- Upon the transition of the LIN signal from Parking to Parked, the BCM pauses the Wipers in their Park Position for the time duration associated with the current intermittent delay interval switch setting and repeats the process
As called out above, the wipe delay interval is a function of the INTERMITTENT Delay Interval Switch setting. When enabled, the Intermittent with Speed feature affects each of the 5 normal Intermittent Delay Intervals as a function of vehicle Speed. The Delay Intervals shall be biased to a shorter delay period with faster vehicle speeds and to a longer delay period with a slower vehicle speed.