Wiper and Washer Systems: Description and Operation

WIPER AND WASHER SYSTEM:

SYSTEM DIAGRAM






SYSTEM DESCRIPTION

1. WASHER LINKED OPERATION
(a) This system operates the front wipers at low speed immediately after washer fluid is ejected when the front washer switch is on for 0.3 seconds or more. When the washer switch is pressed for 1.5 seconds or more, the system operates the front wipers at low speed for approximately 2.2 seconds and then stops the operation.
2. INTERMITTENT OPERATION
(a) The system operates the front wipers once every 1.6 to 10.7 seconds when the front wiper switch is turned to the INT position. The intermittent time can be adjusted to between 1.6 and 10.7 seconds by using the intermittent time adjust dial.
(b) When the wiper control switch is turned to the INT position, current flows from the precharged capacitor C1, through terminals INT1 and INT2 of the wiper control switch, to Tr1 (transistor). When transistor Tr1 is turned on, current flows from terminal +S of the wiper control switch to terminal +1 of the wiper control switch, to terminal +1 of the wiper motor, to the wiper motor and finally to ground, causing the wiper motor to operate. At the same time, current flows from capacitor C1 to terminal INT1 of the wiper control switch and then to INT2. When the current flow from capacitor C1 stops, transistor Tr1 turns off to stop the relay contact point and halts the wiper motor. When the relay contact is off, capacitor C1 begins to charge again and Tr1 remains off until the charging is complete. This period corresponds to the time interval between wiper operations. When capacitor C1 is fully charged, Tr1 turns on and then the relay contact point turns on, causing the motor to operate again. This is the cycle of the intermittent wiper operation. The time interval can be adjusted by using the intermittent time adjust dial (variable resistor) to change the charging time of capacitor C1.