C5buff

Hi to all The fix talked about above has lasted well and worked fine. The main reason for doing it was to save money because there were not many cheap spares about 3 to 4 years ago at that time. The second hand parts avalability now is much better and I recently managed to get the correct version of pump from Ebay for £50. (A new pump from Citroen costs £865). So I have converted back to normal and all is well. The car has been very reliable over the years and I will keep it for a couple more.

It could be that the site has so much info on it that any newbies can look up just about everything for the answers without having to ask any questions as much of it is here.

Hi Have you read my post on page 15 ?. IN the C5 Technical part of the forum(pump runs continuously) the last post on that page gives a way to check the electrics to the pump. Assuming the new pump itself is good then something is missing either the main power or the run command or possibly no chassis ground.

Not sure what it is but for the cost of the Garage diagnostics it might be an idea to buy yourself a Lexia off Ebay and diagnose it with your computer.

Hello Thomas Yes it should be ok. If the ECU is ok on your current pump then you could consider swapping over the transistor switch assembly altogether from the secondhand unit. The whole assembly with commutator brushes transistor etc just pulls off the motor and can then be refitted to your pump. The thing about fitting the second hand pump is whether its ECU will work without needing to be initialised for you cars system. I am not sure about this as someone else did a swap with a secondhand pump and it apparently worked without initalisation. Someone on the forum may know the answer to that one. Anyway I assume when you pulled the run command wire out the pump still ran. Suggesting a short circuit transistor.

Hi If you disconnect the run command line from the pump it should stop. If it dosn't then the transistor switch inside the pump could be breaking down and allowing the pump to run albeit slowly. If this is the case then its a new transistor you will need. This can be obtained from a secondhand pump or if you can still read the details off of the transistor itself then buy just that from sources on the web that sell electronic components. Mine was too badly burnt to read the details so I bought a pump from a chap on ebay as per my post. If it does stop when you remove the run command then the fault is, I am afraid, the ecu mounted on top of the pump. This is the worse case which will require a new pump or a solution like I came up with (see my post). This fix won't be everyones cup of tea. For me it was driven by the need to avoid the high cost of a new pump, the fix cost me 30 quid plus a few hours work. Not forgetting the cost of new oil as a draindown will be required as well.

Hi This is a problem some of us have had before. There are a few incidences of posts on this forum about it. My experience is currently on page 12 of the forum under c5 technical, pump runs continously. If the pump runs for long it is liable to burn out the electric motor and maybe the local wiring as well. So you need to sort it. Click Here to posts - added by Moderator