Circuit/System Description
The body control module (BCM) monitors the control circuit of the wiper relay. The voltage level should be low while the wiper relay is de-energized and near system voltage when the relay is energized. After the BCM receives a low, intermittent, or mist signal from the wiper/washer switch, it responds by applying battery voltage through the wiper relay control circuit to the coil side of the relay, energizing the WIPER Relay. Ground is supplied at all times to the coil side of the WIPER relay from G104.
The windshield washer function is controlled by the body control module (BCM). When the washer switch is pressed, ground is applied through the switch contacts and the signal circuit to the BCM indicating the wash request. The BCM then applies ground through the control circuit to the coil side of the WSH Relay energizing the relay. With the relay energized, battery voltage from the WPR fuse is applied through the switch contacts of the relay, the WSW/PUMP Fuse, and the control circuit to the windshield washer fluid pump.
The body control module (BCM) monitors the wiper high speed relay control circuit only when wiper high speed mode is active. When the wiper high speed mode is requested, the BCM responds by applying a ground through the wiper high speed relay control circuit to the coil side of the relay, energizing the WPR HI Relay.
The body control module (BCM) monitors the windshield wiper switch low signal circuit. When the wiper switch is place in the low position, battery voltage is applied through the switch contacts, a series of resistors, and the wiper switch low signal circuit to the BCM. The BCM then applies battery voltage through the wiper relay control circuit to energize the WPR Relay. When energized, battery voltage from the WPR Fuse is applied through the switch side of the WPR relay then through the switch side of the WPR HI relay to the windshield wiper motor.
Wiper Mist, Delay 1-5, and Low are all low speed wiper motor functions that are controlled by the body control module (BCM). When the wiper switch is placed in one of the LOW speed wiper modes, ground is applied through the switch contacts a series of internal resistors and the wiper switch low signal circuit to the BCM. In response to this signal, the BCM energizes the WPR 1 Relay by applying battery voltage through the wiper relay control circuit to the coil side of the relay. This allows battery positive voltage from the WPR fuse to flow through the switch input side of the WPR 1 Relay and out to the switch input side of the WIPER 2 Relay. Since the wiper high relay is de-energized and its switch contacts are normally closed to the low speed control circuit of the windshield wiper motor, the motor will operate at low speed.
When the wiper switch is placed in the HIGH speed position, ground is applied through the switch contacts and the wiper switch high signal circuit to the BCM indicating the wiper high speed request. The BCM then energizes WPR 1 Relay as stated above and the WIPER 2 Relay by applying ground through the control circuit to the coil side of the relay. With the wiper high relay energized and its switch contacts closed to the high speed control circuit of the wiper motor, the motor will operate at high speed.
The Check Washer Fluid message is controlled by the instrument panel cluster using an input from the washer fluid level switch. The washer fluid level signal circuit is supplied ignition voltage through a resistor then monitored within the instrument cluster. The washer fluid level switch is normally open so the instrument cluster detects ignition voltage on the washer fluid level signal circuit whenever the washer fluid level is not low. When the washer fluid reaches the point where the driver should be informed that the washer fluid is low, the washer fluid level switch closes. When the washer fluid level switch is closed the washer fluid level signal circuit voltage is pulled low, and the instrument panel displays the Check Washer Fluid message on the driver information center. In order to prevent the Check Washer Fluid message from being displayed while sloshing is occurring in the washer fluid container, the instrument cluster is programed with a 1 minute delay before changing states of the Check Washer Fluid message during an ignition cycle.
The windshield washer function is controlled by the body control module (BCM). When the washer switch is pressed, ground is applied through the switch contacts and the signal circuit to the BCM indicating the wash request. The BCM then applies ground through the control circuit to the coil side of the FRT WASH relay energizing the relay. With the relay energized, battery voltage is applied through the switch contacts of the relay, the FRT WASH fuse and the control circuit to the windshield washer fluid pump.
The windshield washer solvent heater operates with the standard windshield wiper washer system, and when a heated washer cycle is activated the solvent heater controls the windshield washers through the washer switch signal circuit to the body control module (BCM). The heater is supplied with high current power and ground circuits that are used to energize the heater coils. The low current logic voltage is supplied to the heater through the RUN relay in the underhood fuse block. The RUN relay is a PCB relay energized by the BCM only while the engine is running. The heated washer cycle operation is activated by a separate switch located on the instrument panel accessory switch assembly. When the heated washer fluid switch is pressed the heated washer switch signal circuit is momentarily grounded and the heated washer cycle is activated. During the heated wash cycle the 3 heater elements in the solvent heater are energized, and when the solvent temperature reaches approximately 70°C (160°F) the heater grounds the washer switch signal circuit until the heated solvent is dispensed. The heated washer cycle will run 4 heat and wash actions unless deactivated by the heated washer switch signal.