Toyota Tundra Service Manual: System Description

SYSTEM DESCRIPTION

1. WINDSHIELD WASHER OPERATION

(a) When the front washer switch is turned on for approximately 0.3 seconds or more, this system operates the front wipers at a low speed immediately after the washer fluid is sprayed. If the switch is turned off within 1.5 seconds, the system stops the wipers when the switch is turned off. If the switch is turned on for more than 1.5 seconds, the system stops the wipers approximately 2.2 seconds after the switch is turned off.

2. INTERMITTENT OPERATION (w/ Intermittent Time Adjust Dial)

(a) The system operates the front wipers according to an adjustable interval time when the front wiper switch is turned to the INT position. The interval can be adjusted between 1.6 to 10.7 seconds using the adjust dial.

(b) When the wiper switch is turned to the INT position, current flows from the already charged capacitor C1 through terminals INT 1 and INT 2 of the wiper control switch, to Tr1 (transistor). When Tr1 turns on, current flows in the following manner: wiper switch terminal +S, terminal +1 (same switch), wiper motor terminal +1, wiper motor, ground. As a result, the wiper motor operates. When the current flow to capacitor CI ends, Tr1 turns off to stop the relay contact point and halts the wiper motor. When the relay contact point turns off, capacitor C1 begins to charge again and Tr1 remains off until charging has been completed. This period of time corresponds to the adjust dial setting. When capacitor C1 is fully charged, Tr1 turns on and then the relay contact point activates, causing the motor to operate. The adjust dial (variable resistor) changes the charge time of capacitor C1.