C5 estate 2007 (facelift MK1) suspension pump oddity.

[sam3b]

Nice easy () one ...
1) Usual "Suspension Faulty Max Speed 55MPH) message.
2) After ignoring it for a while it becomes obvious that the pump is not working as the car gradually gets lower and lower and the up/down buttons just cause further problems.
3) Assume 40A maxi fuse has gone.
4) Lift cover of fuse block, lift maxi fuse carrier out and remove 40A fuse (nearest to wing).
5) Test fuse as looks ok ... fuse is ok.
6) Replace fuse in block, etc. ...
7) Pump now working again !!!!
8) After 2/3 weeks step (1) recurs.
9) Repeat steps 4-7.
10) ... and again ...
11) Add new topic on Citroën part of forum.
12) Wait for someone to explain simply and disclose obvious solution.

[GiveMeABreak]

There should be both a Maxi Fuse and another 40A fuse along the circuit.

When the pump motor gets contaminated with LDS, it creates a black carbon paste from the worn carbon brushes. This conductive paste causes an excessive current draw which leads to overheating and eventual cut-out / or fuse blowing.

It's usually always the same and replacing the fuse is no good as it will just keep happening. Some idiots then bodge it by putting in higher and higher rated fuses and are then surprised when it catches fire

The motor either needs replacing or stripped down and cleaned up.

See Jovani's excellent illustrated post of the clean up on this thread:

viewtopic.php?p=423599#p423599

[Hell Razor5543]

I had this happen on my C5 a couple of times (before the fuse blew and clearly indicated what the problem was). I think there is a thermal cut-out on the pump motor, as when I let her 'rest' for a while the pump started working. I would definitely set a few hours aside to strip and clean the pump motor. It will be useful to get 4L of LDS fluid, some brake cleaning fluid, a toothbrush, and a pair of carpenter pincers (to undo/do up the pipe clips).

[sam3b]

Got an update to this and it's even odder !
Was planning to start work on the pump after the last update as the pump had failed to work again, when I lifted the fuse block to check the 40A fuse but this time with the engine running and the pump started working !!! I left the fuse block raised and played up/down for 20 minutes with the fuse block raised with no problems but as soon as I started to lower the block the pump stopped and started again when I raised it. I reseated everything to no avail ...
Any bright ideas ???

[GiveMeABreak]

You obviously have a wiring issue, possibly a crack or break that is causing the intermittent behaviour, so as you are lifting it the wires are making contact and breaking the contact once lowering.