I have a 2008 se
The front washer doesn’t work, rears fine
I replaced the pump (tried the cheapest one first) no luck,
Before I buy a new switch can you test it with a multi meter
Don’t have a OBD reader yet so can’t check for fault codes
Thanks

Could the jets or tubework be blocked? MY11 SD4 SE Auto

Thank you for reply
Unfortunately not I’ve swopped the pipes over so it sprays front screen when using rear wash switch position
With the switches using a Lin bus connection back to the central junction box
I’m not sure what to expect when I put a multi meter on the switch connections

The operating switch is quite a straight forward 'push to make', but it works relays and logic before the pump is called.

The Manual says

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. FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 76k+ miles) (MY2015)

Thanks I can test switch now and know what to expect
Fingers crossed it’s the switch and not the CJB