screen washer stopped working

screen washer stopped working.

So I disconnected the pump lead and measured only 8.5V across the two socket lead when activating the screen washer - I would expect 12V'ish.

Mine is the facelift model so I checked the two fuses one under the bonnet other under the dash they look visually correct and are low Ohms on the multimeter.

I thought the leads could be corroded but they are not. So I wonder what it could be?

Does this go through a relay like we tend to think of or through something solidstate like a mosfet?

Any thoughts would be appreciated - mot Friday

onepound wrote: ↑Wed Feb 02, 2022 6:18 pm screen washer stopped working.

So I disconnected the pump lead and measured only 8.5V across the two socket lead when activating the screen washer - I would expect 12V'ish.

Mine is the facelift model so I checked the two fuses one under the bonnet other under the dash they look visually correct and are low Ohms on the multimeter.

I thought the leads could be corroded but they are not. So I wonder what it could be?

Does this go through a relay like we tend to think of or through something solidstate like a mosfet?

Any thoughts would be appreciated - mot Friday

Also measure to the earth.

You are looking for 12v to earth to check the supply.

It is a reversible pump to supply front and rear wash wipe

They supply is from the BSM (engine bay fuse box) and there is a mix of solid state and classic relays in there. I don't know which does what because when it is a bad BSM diagnosed, it is quicker and easier to change the whole 'black box'.

There will be two relays in the BSM that run the pump. At least one will have high resistance on the contacts.
These relays are starting to get old now and we are seeing more and more failures of them. There is nothing special about the relays and if you know where to look for them they are easy to find.
HOWEVER if you do not have the skills it's just as easy to replace the whole BSM, as Arfur says.
The other thing to check is corrosion on the contacts of the electrical connectors that plug in to the BSM. Salting the roads in winter forms watery acids that destroy the electrical connections.

Ozvtr wrote: ↑Wed Feb 02, 2022 9:37 pm These relays are starting to get old now and we are seeing more and more failures of them. There is nothing special about the relays and if you know where to look for them they are easy to find.

I think I'd be okay with electronic/electric side at least from hobby stuff I've done over the years

Ozvtr wrote: ↑Wed Feb 02, 2022 9:37 pm There will be two relays in the BSM that run the pump. At least one will have high resistance on the contacts.

What I could with is a schematic or picture of where they are on the BSM so that I can find them easily, I'll look tomorrow to see if they are obvious.

There is a thread running here That you might be interested in.
It's similar (but not the same) to your problem. This a pre-facelift BSM so it wont be the same as yours.
If we ask Arfur nicely, he might get us a facelift circuit diagram of the washer circuit.

Ozvtr wrote: ↑Thu Feb 03, 2022 12:58 am This a pre-facelift BSM so it wont be the same as yours.

yes if(f) mine was like that one the relays could be replaced at small cost. But mine might be all solid state - nevertheless depending how that has been done there might be a possibility of changing a blown chip.

Ozvtr wrote: ↑Thu Feb 03, 2022 12:58 am If we ask Arfur nicely, he might get us a facelift circuit diagram of the washer circuit.

this would be very helpful particularly the BSM.

Thanks for those suggestion.

For an update, though the voltage is a bit low in one direction when measured unconnected I also have found the pump was seized.

Curiously there is no gauze before the pump like other cars -maybe somebody removed it or lost it before me. Indeed they put a gauze on the brake fluid tank which is a nice touch. So maybe the mucous that lives in the washer might have seized the impellor.

Anyway freeing off the pump it now works - though purchasing a replacement would make sense.

As for the bsm whether the relay is partially damaged I do not know. It is known that solid state devices such as mosfets can have soft faults rather than open/short faults .

It would be nice to know whether the bsm has a fujitsu board relay like the 2002 model or a solid state solution>>

The washer jet motor and the wipers circuit diagrams appear in the Citroen C3 Haynes manual.

My diagrams are currently offline

This is a facelift model. Haynes manual doesn't cover it. The BSM wont be the same.
It wont have solid state switching. Relays are cheaper. Only requires 2 relays to reverse a circuit but it requires a 4 way 'H' pattern to reverse a circuit using semi conductors. Most makes of cars have plug in relays to make replacing easier. Even today (That's a dig at PSA ).

Ozvtr wrote: ↑Thu Feb 03, 2022 9:25 pm Only requires 2 relays to reverse a circuit but it requires a 4 way 'H' pattern to reverse a circuit using semi conductors. Most makes of cars have plug in relays to make replacing easier. Even today (That's a dig at PSA ).

For the older model I've sourced the fujitsu relays mentioned in that post and they are available and not expensive if purchased from overseas.

observing that there was a voltage drop from 12V suggests that this problem might come back.

It would be nice to know what they are on the facelift without actually removing the bsm so one purchase them ahead of a possible failure and repair attempt as they are inexpensive. If they are still electomechanical relays as appose to solid state, all the better.

I'll try to do some research on what they might be and if I discover anything I'll report back