Principles Of Operation

Wipers and Washers

Principles of Operation

Windshield Wiper System

The wiper and washer system functions are activated by the wiper/washer switch which provides an input to the Body Control Module (BCM). The BCM then provides an output to operate the desired wiper system feature. The windshield and rear window wiper systems share the window washer pump and cannot be used simultaneously. The windshield wiper system only operates when the ignition is ON.

The windshield wiper system offers 4 wipe modes:

- Single
- Intermittent (6 settings)
- Normal
- Fast

The wiper system setting of the wiper/washer switch is transmitted to the BCM to actuate the wiper motor and set the wiper speed. Normal wipe speed remains available in the event of BCM failure.

Windshield Intermittent Wipe

The windshield intermittent wipe setting of the wiper/washer switch is transmitted to the BCM to actuate the wiper motor and set the wiper delay interval. The wiper/washer switch has 6 intermittent wiper delay settings ranging from a short to a long delay:

- Level 1 delay = 1.2 seconds
- Level 2 delay = 4 seconds
- Level 3 delay = 8 seconds
- Level 4 delay = 12 seconds
- Level 5 delay = 17.5 seconds
- Level 6 delay = 25 seconds

Windshield Wiper Motor

The integrated park switch is directly connected to the BCM. The windshield wiper motor park switch contacts are open in all wiper motor positions except PARK. When the windshield wiper motor park switch contacts are open, the windshield wiper motor remains switched on even if a signal from the BCM requests the wipers to stop. In PARK position, the windshield wiper motor park switch contacts create a ground connection. The BCM recognizes this ground connection and switches the windshield wiper motor off.

Front Washer System

When the front washer system is switched ON, the BCM switches the window washer pump ON. The windshield and rear window wiper systems share the window washer pump and cannot be used simultaneously. The BCM delays wiper operation for 360 ms after operation of the wiper/washer switch washer setting. If the wiper/washer switch washer setting is not operated for at least 360 ms, the BCM does not switch the windshield wiper motor ON. The BCM activates the windshield wiper motor for as long as the wiper/washer switch washer setting is operated, up to 10 seconds maximum. After the washer pump is turned OFF, the BCM allows the windshield wipers to wipe 4 more times. An additional courtesy wipe follows the 4 wipes after a brief pause.

Rear Window Wiper System

The rear window wiper system only operates if the ignition is ON. The position that the wiper/washer switch is in for the front windshield wipers determines the action of the rear wiper:

- When the wiper/washer switch is in a position that commands the rear wiper ON and the front windshield wipers are in the OFF position, the rear wiper is activated by the BCM with a 4 second delay between wipes.
- When the front windshield wipers are being operated in the intermittent mode, the rear wiper also operates in the intermittent mode. The rear wiper reacts along with the front windshield wipers to changes in the position of the rotary interval switch. When the rotary switch is positioned for a long delay between wipes, the rear wiper also operates with a long delay between wipes. The same is true for a short delay between wipes.
- When the front windshield wipers are operated at normal speed, the rear wiper operates with a 4 second delay between wipes when switched on.
- When the front windshield wipers are operated at high speed, the rear wiper operates continuously when switched on.

Rear Washer System

When the rear wash system is switched ON, the BCM supplies power to the washer pump. Reversing the polarity of the pump enables the washing fluid to flow to the rear washer jet instead of the front washer jets. The BCM activates the window wiper for as long as the window washer switch is operated. The window washer pump is switched OFF after a maximum of 10 seconds. After clearance from the switch, the BCM allows the wiper to wipe 2 or 3 more times.

Rear Wiper Motor

The integrated park switch is directly connected to the BCM. The rear window wiper motor park switch contacts are closed in all rear window wiper motor positions except PARK. When the rear window wiper motor park switch contacts are closed, the rear window wiper motor is supplied with a voltage by the BCM. When the rear window wiper motor reaches the PARK position, the park switch contacts open and the power supply is interrupted by the BCM. While the wiper/washer switch remains in the rear washer position, the rear window wiper motor is again supplied with a voltage by the BCM and continues to run. This process is repeated during every revolution of the rear window wiper motor.