power wash failure

[Setch]

Two days from MOT my powerwash for the headlamps has decided to pack up on both sides, wipers themselves work fine. Last week it worked fine, but I did run out of water last week.

My immediate reaction was it was probably sludge build up in water reservoir has clogged the pump filters (had that problem last year). So cleaned out the res, cleaned both filters, re-assembled filled with fresh water and tried again, still not working. Checked fuse 40 (30A) which was fine too. It got to dark to continue so need to pick up tomorrow.

Any ideas where to go next?

My thoughts are disconnect the hose from the water pump and see if it squirts anything out, but i am not sure how much water will flood out! If nothing squirts out check voltage across two pins to see if it goes to 12V after operating the windscreen washers, if it does it points to pump. If it does squirt i'm figuring it is a blockage in the pipe?

 

[mrscalex]

Not 100% sure it's in the MOT. I think it is. But perhaps @t-tony could confirm.

Sounds like a reasonable test plan btw.

 

[t-tony]

It won't matter for the test. My Z4 has h/light washers but standard bulbs so not a testable item. Search the internet for current MOT tester's manual.
The pipe from the pump came aprt on my car a couple of weeks ago, I reconnected the pipe but now I notice they're not working. When I find out why I'll let you know.

Tony.

 

[AleNod]

It's not just a simple airlock is it? Don't know the shape of the pipe run.

I'll shuttup and go and site quietly in the corner now...!

 

[Setch]

Update on this: I got a friend to operate the washers while I listened for the HP washer pump, and heard nothing. So I measured the voltage across pins 1 & 2 of the connector with a peak hold DVM then operated the washers 3 or 4 times, nothing registered. So narrows it down to poor connection (pins or earth), faulty relay or GM5 issue. Then weirdly, driving home the RH washer worked (weakly) once in about 6 washes.

Looked into MOT regs. Reg 4.1.6 Headlamp cleaning devices states only applicable for post 2009 cars, so took the car anyway. On the way it started behaving more consistently on both lights (don't you just love intermittent problems). It passed the MOT without advisories, so I will leave all alone at the moment, but my nuch is an intermittent wiring problem, most likely ground connection.