Wiper and Washer Systems: Description and Operation

SYSTEM DESCRIPTION
The two-speed wiper non-depressed park system is a permanent magnet (PM) positive park wiper with a dynamic brake and a separate washer pump assembly.
The pulse windshield wiper and washer system consists of a permanent magnet positive park pulse wiper, a washer pump mounted under the washer bottle and a turn signal type wiper/washer switch.
The pulse and demand wash functions are controlled by a plug-in printed circuit board enclosed in the wiper's die-cast aluminum housing cover.

Wiper Motor
Internal parts of the wiper motor assembly, field magnet, armature, drive gear, park switch actuator and brush holder assembly are enclosed in an aluminum die-cast housing with a plastic cover. The housing and cover are attached to each other by seven rivets. A radio frequency interference suppressor is located in the terminal connector on the wiper motor. A strap attached to one of the motor bolt hole grommets provides a ground for the suppressor. An automatic reset type circuit breaker located on the motor brush holder assembly protects the motor. A fuse in the fuse block protects the vehicle wiring.
There are four terminals which are lettered for illustrative purposes. The function of each terminal is covered in the explanation that follows.
Use care when disconnecting the lock-type connectors that attach vehicle wiring to the wiper.
The wiper motor has three brushes: common, low speed and high speed. When the ignition switch is ON, a (+) 12V circuit is applied to both the low and high speed fixed contacts in the multi-function lever. The low and high speed brushes are connected to the multi-function lever through terminals C and D. The armature is grounded through the common brush via the ground strap.

Fluidic Washer System
The system consists of a solvent container, pump, washer hose and nozzle.
The fluidic washer system is controlled by a small plastic element designed into the washer nozzle. As water is forced through this insert, the design of the mechanism creates an oscillating power stream. This fluidic washer system produces larger, more widely dispersed droplets, resulting in a more efficient cleaning action.
A correctly operating wiper-washer system has a spray pattern that cleans 75 % of the wipe pattern within ten wiper cycles.
If the nozzles become plugged, apply air pressure. If nozzle remains plugged, the nozzle must be replaced. If the spray pattern is too low or too high on the windshield, wedge-type adjustment shims can be used. Placement of a shim under the nozzle mounting bracket will raise the pattern three degrees. Reverse installation of the same shim will lower the pattern three degrees. Pump and wiper motor service remain unchanged. Shim provisions have not been provided for the rear fluidic washer nozzles.

SYSTEM OPERATION
The electronic printed circuit board controls all the timing and washer commands. When the wash button is pushed for more than 0.3 second, a demand wash is performed in 1.5 second intervals for as long as the button is held followed by approximately 6 seconds of dry wipes and a shut off.
Rotating the switch to either the LOW or HIGH speed position completes the respective circuit and the wiper motor runs at that speed.
Rotating the switch to the pulse mode operates the motor intermittently and the delay can be varied by rotating the switch.
An instantaneous wipe can be obtained by rotating the switch to the mist position and a continuous wipe will be performed if the switch is held.

Low And High Speed Circuits
Moving the multi-function lever to the low or high speed position completes the respective brush circuit to (+) 12 volts DC at the multi-function lever and the wiper motor runs at that speed.

Shutting The Wiper Off
When the wiper is turned off at the multi-function lever, in order to have the blades stop in their normal park position and the wiper motor shut off properly, the motor operates in low speed. This is accomplished as follows: with the multi-function lever in the "Off' position, the low speed brush circuit is completed to (+) 12 volts DC at the multi-function lever through a park switch located on the brush assembly (terminals A and B). The park switch contacts are normally closed and this permits the wiper to continue to run.
When the blades reach their park position, a cam on the large gear moves the park switch actuator that opens the normally closed positive park switch and grounds the wiper motor. This accomplishes a reversal of the motor flux path which causes a no-coast positive park, shutting off the wiper.

Washer Pump
Actuating the washer portion of the multi-function lever completes the washer pump motor circuit to ground and mechanically moves the wiper motor switch to the low-speed position. This dual function starts the wiper motor and washer operation at the same time. The washer pump runs only while the wash switch is activated.
The washer pump consists of a permanent magnet motor and pump assembly that is mounted on the solvent container. The wiper motor can be operated only when the ignition switch is in the run or accessory position.