Wiper/Washer System Description and Operation (Heated Washer System)

Wiper/Washer System Description and Operation (Heated Washer System)

The heated windshield washer system consists of the following components:

* Windshield washer solvent heater assembly
* Heated washer fluid switch
* WSW HTD Fuse 60 A
* HTD/COOL/IGN3 Fuse 10 A
* Ground G304
* Ground G300

The body control module (BCM) is also involved in the operation of the heated windshield washer system.

Refer to Master Electrical Component List (Component Locations).

Heated Washer System Operation

The intent of the Heated Washer Fluid Feature is to automatically clear the windshield of snow or ice upon activation. The system may also be used to improve the bug clearing performance of the wash feature under summer driving conditions. When the heated wash switch is pressed, the driver information center (DIC) will display the HEATING WASH FLUID WASH WIPES PENDING message for 2 seconds and the heater assembly heats the wash fluid to approximately 70°C (160°F). The total duration of the initial heat up cycle may take up to 45 seconds. Once the proper temperature is reached, the heater assembly will request the body control module (BCM) to activate the windshield wash cycle. The heater assembly will maintain an active wash request until the wash fluid temperature drops to 40° C when the wash cycle request will be de-activated allowing the wash fluid to heat up again. The fluid heating and wash application will automatically be repeated 3 more times. Upon completion of the 4 wash cycles, the system will transition to off. The automatic heated wash mode may be terminated at any time by pressing the heated washer fluid switch. The DIC will then display the HEATED WASHER FLUID WASHER SYSTEM OFF message.

Heated Washer System Power and Grounds

High current battery voltage is supplied to the windshield washer solvent heater assembly from the 60A WSW HTD Fuse located in the underhood fuse block. The washer solvent heater uses this voltage to power the 3 heater coils. Battery positive voltage from the 10A HTD/COOL/IGN3 Fuse located in the rear fuse block is applied to the windshield washer solvent heater assembly with the ignition in the ON position. This voltage is used to power up the logic in the heater assembly. The washer solvent heater assembly is supplied with 2 separate ground circuits from G304. One circuit is used to supply ground to the logic side of the heater assembly and the second one is used as a ground for the 3 heater coils. Ground is supplied to the heated washer fluid switch from G300. Refer to Wiper/Washer Schematics ([1][2]Electrical Diagrams).

Heated Washer System Circuit Description

The washer solvent heater assembly provides a 5 volt reference voltage through the heated washer fluid switch signal to the heated washer fluid switch located on the Turn Signal/Multifunction Switch stalk. When the heated washer fluid switch is pressed, the signal circuit is closed to ground and the 5 volt supply is dropped across the resistor indicating the heated wash cycle request. The heater assembly sends a low side drive pulse width modulation (PWM) signal through the heated washer indicator signal circuit requesting the instrument panel cluster (IPC) to display the DIC HEATING WASH FLUID WASH WIPES PENDING message. After the above mentioned washer solvent temperature is reached, the heater assembly pulls the windshield washer switch signal circuit low requesting the BCM to activate the wash cycle.

Automatic Shutdown Protection Feature

Below are automatic shutdown modes built into the heated wash system. When any of these modes are activated, the heated assembly will shut down and request the IPC to transition the DIC to display the HEATED WASHER FLUID WASHER SYSTEM OFF message.

* Under Voltage - The system will shut down if battery voltage goes under 10 volts for 5 seconds.
* Fail to Heat - The system will shut down if the fluid does not heat by 5°C (41°F) within 28 seconds.
* Fail to Cool - The system will shut down if the fluid does not cool by 2°C (36°F) 4.75 seconds.

The following shutdown modes will require an ignition cycle to resume normal operation:

* Printed Circuit Board (PCB) Temperature Over Threshold - The system will shut down if the unit PCB is greater than 125°C (257°F) for more than 2 seconds.
* Temperature Sensor Shorted High - An internal heater assembly measurement. The system will shut down if an internal short is detected.
* Automatic Over Temperature - The system will shut down if fluid temperature exceeds 85°C (185°F) for 2 seconds.
* Automatic Over Voltage - The system will shut down if battery voltage exceeds 16.4 volts for 4 seconds.