Wipers/Washers - Operation

OPERATION

FRONT WIPER/WASHER SYSTEM

The vehicle operator initiates all front wiper and washer system functions with the control stalk of the right (wiper) multi-function switch that extends from the right side of the steering column, just below the steering wheel. Rotating the control knob on the end of the control stalk selects the Off, Delay, Low, or High front wiper system operating modes. In the Delay mode, the control knob also allows the vehicle operator to select from one of five intermittent wipe Delay intervals. Pulling the right control stalk downwards actuates the momentary front wiper system Mist mode switch, while pulling the right control stalk towards the steering wheel actuates the momentary front washer system switch. The right multi-function switch provides hard wired resistor multiplexed inputs to the Body Control Module (BCM) for all of the front wiper system functions, as well as separate hard wired sense inputs to the BCM for the high speed continuous wipe and front washer system functions. The BCM in turn sends a bus message to the IPM to activate the front wiper low speed, high speed, 5 intermittent wipe delays, wipe after wash, mist function and the washer pumps for both the front and rear wiper systems.

The front wiper and washer system will only operate when the ignition switch is in the Accessory or On positions. Battery current is directed from a B(+) fuse in the Integrated Power Module (IPM) to the wiper and washer system fused ignition switch output (run-acc) circuit. The right multi-function switch circuitry uses this battery feed to send a PCI data bus message to the BCM which will then pass it on the IPM to energize the front wipers/washers.

When diagnosing the front wiper/washer system, use a scan tool and the appropriate diagnostic information.

FRONT WIPER/WASHER OPERATING MODES

CONTINUOUS WIPE MODE

When the Low position of the control knob on the control stalk of the right (wiper) multi-function switch is selected, the Body Control Module (BCM) sends a PCI data bus message to the IPM to energize the wiper motor. This directs battery current through low speed brush of the front wiper motor, causing the front wipers to cycle at low speed. When the High position of the control knob is selected, the BCM sends a PCI data bus message to the IPM to energize the wiper motor. This directs battery current through the high speed brush of the front wiper motor, causing the front wipers to cycle at high speed.

When the Off position of the control knob is selected, the BCM sends a PCI data bus message to the IPM to de-energize the wiper motor, then one of two events will occur. The event that will occur depends upon the position of the wiper blades on the windshield at the moment that the control knob Off position is selected. If the wiper blades are in the down position on the windshield when the Off position is selected, the park switch that is integral to the front wiper motor is closed to ground and the wiper motor ceases to operate.

If the wiper blades are not in the down position on the windshield at the moment the Off position is selected, the park switch is closed to battery current from the fused ignition switch output (run-acc) circuit of the front wiper motor. The park switch directs this battery current to the low speed brush of the wiper motor through the wiper park switch sense circuit. This causes the wiper motor to continue running at low speed until the wiper blades are in the down position on the windshield and the park switch is again closed to ground.

INTERMITTENT WIPE MODE

When the control knob on the control stalk of the right (wiper) multi-function switch is moved to one of the five Delay interval positions, the BCM electronic intermittent wipe logic circuit responds by calculating the correct length of time between wiper sweeps based upon the selected delay interval input. The BCM monitors the changing state of the wiper motor park switch through a hard wired front wiper park switch sense circuit input. This input allows the BCM to determine the proper intervals at which to send the PCI data bus message to the IPM to energize and de-energize the front wiper motor intermittently for one low speed cycle at a time.

The BCM logic is also programmed to provide an immediate wipe cycle and begin a new delay interval timing cycle each time a shorter delay interval is selected, and to add the remaining delay timing interval to the new delay interval timing before the next wipe cycle occurs each time a longer delay interval is selected. The intermittent wipe mode delay times are speed sensitive. The BCM monitors vehicle speed messages received from the Powertrain Control Module (PCM) over the PCI data bus in order to provide the speed sensitive delay intervals. Above about sixteen kilometers-per-hour (ten miles-per-hour) the delay is driver adjustable from about one-half second to about eighteen seconds. Below about sixteen kilometers-per-hour (ten miles-per-hour) the delay times are doubled, from about one second to about thirty-six seconds.

MIST WIPE MODE

When the control stalk of the right (wiper) multi-function switch is moved to the momentary Mist position, the BCM sends a bus message to the IPM to energizes the wiper on/off relay for as long as the Mist switch is held closed, then de-energizes the relay when the state of the Mist switch input changes to open. The BCM can operate the front wiper motor in this mode for only one low speed cycle at a time, or for an indefinite number of sequential low speed cycles, depending upon how long the Mist switch is held closed.

WASH MODE

When the control stalk of the right (wiper) multi-function switch is moved to the momentary front Wash position while the control knob is in the Low or High positions, the BCM receives this information and sends a bus message to the IPM to turn on the front washer pump/motor unit. This will cause the front washer pump/motor unit to be energized for as long as the front Wash switch is held closed, and to de-energize when the front Wash switch is released.

When the control stalk of the right (wiper) multi-function switch is moved to the momentary front Wash position while the control knob is in one of the Delay interval or Auto sensitivity positions, the front washer pump/motor operation is the same. However, the BCM sends a bus message to the IPM to energizes the wiper on/off relay to override the selected delay interval or auto sensitivity level and operate the front wiper motor in a continuous low speed mode for as long as the front Wash switch is held closed, then de-energizes the relay and reverts to the selected delay mode interval or auto sensitivity level several wipe cycles after the front Wash switch is released. The BCM detects the front Wash switch state through a hard wired washer pump motor switch output circuit input from the right multi-function switch.

WIPE-AFTER-WASH MODE

When the control stalk of the right (wiper) multi-function switch is moved to the momentary front Wash position while the control knob is in the Off position, the BCM detects that switch state through a hard wired washer pump motor switch output circuit input from the right multi-function switch. The BCM responds to this input by sending a PCI data bus message to the IPM to energize the washer pump as long as the Wash switch is held closed, then de-energizes the washer pump several wipe cycles after the front Wash switch is released. The BCM monitors the changing state of the wiper motor park switch through a hard wired front wiper park switch sense circuit input. This input allows the BCM to count the number of wipe cycles that occur after the front Wash switch state changes to open, and to determine the proper interval at which to send a PCI data bus message to the IPM to de-energize the washer pump to complete the wipe-after-wash mode cycle.

REAR WIPER/WASHER SYSTEM

The vehicle operator initiates all rear wiper and washer system functions with the control stalk of the right multi-function switch that extends from the right side of the steering column, just below the steering wheel. Rotating the control sleeve on the control stalk to a detent position selects the rear wiper system operating mode. Moving the switch control stalk forward actuates the momentary rear washer system switch. The right multi-function switch provides hard wired outputs to the rear wiper motor and the rear washer pump/motor for all rear wiper and washer system functions.

The rear wiper and washer system will only operate when the ignition switch is in the Accessory or On positions. When the ignition switch is in the Accessory or On positions, battery current from a fuse in the IPM is provided to the right multi-function switch through a fused ignition switch output (run-acc) circuit. The internal circuitry of the right (wiper) control stalk of the right multi-function switch then provides battery current signals through a rear wiper motor control circuit and a rear wiper motor delay control circuit to the rear wiper motor. The multi-function switch circuitry also uses this battery current input to directly control the operation of the rear washer pump/motor unit.

When diagnosing the rear wiper/washer system, use a scan tool and the appropriate diagnostic information.

REAR WIPER/WASHER OPERATING MODES

CONTINUOUS WIPE MODE

When the On position of the control sleeve on the right (wiper) multi-function switch control stalk is selected, the multi-function switch circuitry directs a battery current signal to the rear wiper motor through the rear wiper motor control circuit, causing the rear wiper to cycle continuously at a fixed speed.

INTERMITTENT WIPE MODE

When the Delay position of the control sleeve on the right (wiper) multi-function switch control stalk is selected, the multi-function switch circuitry directs a battery current signal to the rear wiper motor through the rear wiper motor delay control circuit, causing the rear wiper to cycle intermittently at a fixed delay interval.

WASH MODE

When the control stalk of the right (wiper) multi-function switch is moved to the momentary Wash position, the multi-function switch circuitry directs battery current to the rear washer pump/motor through the rear washer pump motor control circuit, and battery current signals are also provided to the rear wiper motor on both the rear wiper motor control circuit and the rear wiper motor delay control circuit. This will cause the rear washer pump/motor to be energized and the rear wiper to cycle continuously at a fixed speed for as long as the rear Wash switch is held closed.

WIPE-AFTER-WASH MODE

When the control stalk of the right (wiper) multi-function switch is released from the momentary Wash position, the rear washer pump/motor is de-energized, but the circuitry within the rear wiper motor will provide several additional wipe cycles to complete the wipe-after-wash mode cycle.