turn basin tap on shower works

[adrianfs1]

hello guys.
hope someone can help me with this annoying problem.
went to a job, customer complained that her shower wont work, then said if she turn basin tap on shower works. Now, i have disconnected the feed and ran the water, no restrictions. reconnected turned water back on and the shower worked but only for a minute, then realised that the pressure light was on,on the shower, there has been no work carried out on the plumbing, and this fault has only just started, the shower is a mira sport,
was wandering if it could be a faulty pressure switch,works fine for a couple of mins when the pressure is dropped but dies off within 2-3 mins,
any suggestions much appreciated. Hope ive explained it ok.

 

[Plumbstar Tom]

i would suspect maybe its the solenoid valve at fault here?

 

[adrianfs1]

hi Tom, would the solinoid valve cause the pressure drop, all power is on, and it sounds like it wants to work, as i said if you turn the shower off, open the whb tap then turn the shower back on, it works.......MAD