Wiper and Washer Systems: Description and Operation

Wipers and Washers

COMPONENT LOCATION









OVERVIEW
Windshield wiper and washer operation is controlled by the CJB in response to driver input and if fitted, signals from the rain sensor. The front wipers have 4 operational states:
- Flick wipe
- Intermittent/Auto (vehicles without/with rain sensor fitted)
- Slow wipe
- Fast wipe.
The 'Auto' function requires an input from the rain sensor. The rain sensor is mounted on the inner surface of the windshield and transmits an infra-red signal to determine the amount of water on the outer surface of the windshield. A value is then transmitted to the CJB over the Local Interconnect Network (LIN) bus.
The CJB also controls operation of the headlamp wash function. For more information, refer to 'Headlamp Washers' below.
The rear screen wiper system operates independently of the windshield wiper system and is controlled by the CJB on receipt of LIN bus messages from the RH steering column multi-function switch.

NOTE:
The windshield and rear screen washers utilize the same pump meaning only 1 wash function, either front or rear, can be performed at any one time.


WINDSHIELD WIPER MOTOR









The windshield wiper motor drives a gear wheel via a worm drive attached to the motor spindle. The gear wheel has a central spigot which provides the attachment point for the motor crank. The motor crank attaches directly to the wiper linkage link rods and is secured by a single nut. The motor assembly and wiper linkage are a single component and must be removed or replaced as such. For additional information, refer to Windshield Wiper Motor Service and Repair
The motor assembly is connected to the vehicle harness by a 4 pin electrical connector. The electrical connector provides 2 battery voltage feeds from the BJB, a wiper park feed from the CJB, and a ground path for the motor assembly.

WINDSHIELD WIPER LINKAGE









The windshield wiper linkage comprises a main tube with a pivot housing at each end. The windshield wiper motor is mounted centrally on the main tube and acts directly on a pair of link rods. The link rods convert the rotary motion of the motor into a linear, reciprocating motion.
The link rods are connected to the main tube via a crank at each end. The cranks convert the linear, reciprocating motion of the link rods into a rotary, reciprocating motion of the pivots. This translates to a reciprocating motion of the wiper blades across the windshield.
The windshield wiper linkage and motor assembly are a single component and must be removed or replaced as such. For additional information, refer to Windshield Wiper Motor Service and Repair

RAIN SENSOR





The rain sensor is located behind the interior mirror trim casing and sits in a bracket which is bonded to the inner surface of the windshield. The sensor contains a number of transmitter and receiver diodes which emit and receive infrared light. By comparing the received light signal against the known transmitted light signal, the rain sensor can determine the amount of water on the outer surface of the windshield.

NOTE:
A = Clean and dry windshield; B = Wet and dirty windshield









NOTE:
The rain sensor also contains a light sensor. The light sensor is used to control operation of the automatic headlamps function. For additional information, refer to Exterior Lighting Exterior Lighting
The rain sensor is connected to the vehicle harness by a 3 pin electrical connector. The electrical connector provides a power feed from the CJB, a LIN bus connection to the CJB and a ground path.

REAR SCREEN WIPER MOTOR









The single speed rear screen wiper motor is mounted on the inner surface of the liftgate and is secured by 3 bolts. Rubber bushes isolate the motor assembly from the body to help reduce the transmission of motor operating noise to the liftgate. The motor is located on a worm drive mechanism, which converts the rotary motion of the motor output spindle into the required arc for the rear wiper blade.
A 3 pin electrical connector is used to connect the rear screen wiper motor to the vehicle harness. The electrical connector provides a power feed to the motor from the AJB, a wiper park feed from the CJB, and a ground path.
The AJB contains the rear screen wiper relay. Operation of the relay is controlled by the CJB, which provides feed and ground paths according to logic contained within its software.

CONTROL DIAGRAM

NOTE:
A = Hardwired; N = Medium speed CAN bus; O = LIN bus









PRINCIPLES OF OPERATION
The wiper and washer system can operate in a number of different ways when the vehicle is in power mode 4 through 8. Requests from the RH steering column multi-function switch are transmitted over the LIN bus to the CJB, which is the main controller for the system.

Windshield Wiper Slow Wipe
On receiving a request for slow windshield wiper operation the CJB will energize relay 11 in the BJB. When energized, relay 11 provides a feed to the switch contacts of relay 8, which is also located in the CJB. Relay 8 is the fast/slow wipe relay. When slow wipe has been requested relay 8 remains de-energized, allowing a feed to flow across the relay switch contacts to the windshield wiper motor slow speed brush contacts.

Windshield Wiper Fast Wipe
On receiving a request for fast windshield wiper operation the CJB will energize relay 11 and relay 8 in the BJB. When energized, relay 11 provides a feed to the switch contacts of relay 8. The energized relay 8 provides a feed to the windshield wiper motor fast speed brush contacts.

Windshield Wiper Intermittent Wipe
On receiving a request for intermittent windshield wiper operation, the CJB will energize relay 11 in the BJB to operate the wipers at slow speed. Software contained within the CJB interprets the time delay requested and controls operation of relay 11 accordingly.
The intermittent wiper setting broadcast on the LIN bus to the CJB equates to the following time delays.





In the event of a LIN bus failure between the CJB and the RH steering column multi-function switch, the CJB will default to 'Limp Home' mode (see below).

Windshield Wiper Automatic Wipe
On receiving a request for automatic windshield wiper operation, the CJB interprets LIN bus messages received from the rain sensor. The rain sensor provides LIN bus messages with values ranging from 0 to 7. A signal value of 0 is interpreted by the CJB as there being no water on the windshield.
A signal value from 1 to 5 is interpreted by the CJB as there being a small amount of water hitting the windshield. In this instance, the CJB initiates a slow wipe routine as detailed in the 'Windshield Wiper Slow Wipe' section above.
A signal value from 6 to 7 is interpreted by the CJB as there being a large amount of water hitting the windshield. In this instance, the CJB initiates a fast wipe routine as detailed in the 'Windshield Wiper Fast Wipe' section above.
Rain sensor sensitivity can be adjusted by turning the rotary control on the RH steering column multi-function switch to the required position. Six different sensitivity settings are available, which are broadcast over the LIN bus to the CJB.

NOTE:
The CJB will only change a fast wipe routine to a slow wipe routine if the rain sensor value is lower than 4.


Windshield Wiper Flick Wipe
On receiving a request for flick wipe operation the CJB will operate the windshield wipers as described in the 'Slow Wipe' section above until the request is removed.

Windshield Wiper Park
The windshield wiper park switch is integral with the windshield wiper motor. The park switch ensures the windshield wipers return to the park position if the windshield wiper request is cancelled mid-stroke.
The CJB is connected to one side of the park switch. The park switch contacts are open when the wipers are in any position except the park position. While the switch contacts are open, the CJB continues to energize relays 11 and 8 in the BJB, even if a LIN bus signal has been received from the RH steering column multi-function switch requested the wipers are stopped.
When the wipers reach the park position, the park switch contacts close and a ground path is created. When the CJB registers this ground path its software logic determines the wipers are in the park position and de-energizes relays 11 and 8 in the BJB.

Windshield Wiper Limp Home Mode
In the event of a LIN bus failure between the CJB and the RH steering column multi-function switch when the windshield wipers are active, the CJB will enter limp home mode. In limp home mode, the CJB will only power the windshield wipers at slow speed.

Windshield Wiper Service Position
The windshield wipers can be parked on the windshield to aid the fitment of new wiper blades. For more information, refer to the 'Owners Handbook'.

Rear Screen Wiper
On receiving a request for rear screen wiper operation the CJB will energize relay RA2 in the AJB. When energized, relay RA2 provides a feed to the rear screen wiper motor. The rear screen wiper operates intermittently, with a delay between wipes of approximately 6 seconds. The CJB controls operation of relay RA2, and consequently rear screen wiper motor operation, accordingly.
The CJB also provides a feed to the rear screen wiper motor park switch. The park switch is integral with the rear screen wiper motor and ensures the wiper returns to the park position if the rear wiper request is cancelled mid-stroke. The park switch contacts are closed when the rear wiper is in any position except the park position. This allows the CJB to return the rear wiper to the park position when relay RA2 is de-energized.
The CJB will also power the rear screen wiper motor if reverse gear is selected while the windshield wiper function is active. On vehicles fitted with an automatic transmission, the reverse gear signal originates in the Transmission Control Module (TCM). The TCM broadcasts a reverse gear signal over the high speed CAN bus to the CJB, which responds by operating the rear wiper.
On vehicles fitted with a manual transmission, the reverse gear signal originates at the reverse gear switch. The reverse gear switch is hardwired to the CJB.

Windshield Washers
On receiving a request for windshield washer operation the CJB will energize the front washer control relay. This allows a battery voltage feed to flow to the washer pump. A ground path for the pump is provided by the de-energized rear washer control relay. Both washer control relays are integral with the CJB.
When windshield washer operation is requested, the windshield washers will operate. The CJB will delay wiper operation for 100 ms after the washer switch is pressed. If the switch is pressed for less than 100 ms, the CJB will not operate the wipers.
The CJB will power the windshield wipers for as long as washer operation is requested, although the washers will time out after 10 seconds. After the washer switch has been released, the CJB will operate the windshield wipers through 2 more wipe cycles.

Rear Screen Washer
On receiving a request for rear screen washer operation the CJB will energize the rear washer control relay. This allows a battery voltage feed to flow to the washer pump. A ground path for the pump is provided by the de-energized front washer control relay. Reversing the polarity of the pump (see 'Windshield Washers' above) allows washer fluid to be directed to the rear screen washer jet rather than the windshield washer jets. The rear screen washer jet is incorporated into the high mounted stop lamp.
The rear screen washer will operate for up to 10 seconds if continuously requested. When rear screen washer operation is requested, the rear screen wiper will operate continuously until the switch is released. After the switch has been released, or following 10 seconds of continuous operation, the CJB will operate the rear screen wiper through 2 or 3 more wipe cycles.

Headlamp Washers
When the vehicle enters ignition mode 4 (accessory) to 7 (engine running) the first windshield wash request greater than 100 ms will operate a headlamp power wash sequence. The CJB will then start a 10 minute timer. If 5 requests for windshield washer operation are made within this 10 minute window, the CJB will power the headlamp washers upon receiving the fifth request. When this occurs, the 10 minute timer is reset to 0.
If the CJB receives no windshield washer requests during a 10 minute window, the headlamp washers will operate on the first request received after the 10 minute window has elapsed. Again, once the headlamp washers have been operational, the CJB resets the timer to 0.
The headlamp washers will only operate when the headlamps are on. The CJB receives a 'lights on' signal from the light control module over the LIN bus.
When headlamp washer operation is required, the CJB energizes relay 9 in the BJB, allowing a battery voltage feed to power the headlamp washer pump. A ground path for the washer pump is provided by the de-energized relay 12, which is also located in the BJB. This sequence of events provides washer fluid to the headlamp 1 washer jets.
After this sequence the power supply to the pump is reversed. The CJB does this by de-energizing relay 9 and energizing relay 12. This allows the pump to provide washer fluid to the headlamp 2 washer jets. The sequence of events runs as follows:
- Power to headlamp 1 washer - 500 ms
- Delay to power headlamp 2 washer - 100 ms
- Power to headlamp 2 washer - 500 ms
- Delay (soak time) to power 1 headlamp washer - 700 ms
- Power to 1 headlamp washer - 500 ms
- Delay to power 2 headlamp washer - 100 ms
- Power to 2 headlamp washer - 500 ms
If there is less than 1 liter (0.26 US gallon) of washer fluid in the washer fluid reservoir, the CJB will suspend headlamp washer operation. The fluid level switch is hardwired to the CJB, which also transmits a low fluid signal to the instrument cluster over the medium speed CAN bus. For additional information, refer to Instrument Cluster Description and Operation
For additional information, refer to Information and Message Center Description and Operation