C5 Suspension Pump

[Guest C5buff]

Hi

My C5 high pressure suspension pump runs all the time when ignition is on. The door opening and boot opening cause the normal 5seconds or so run and then cut off so those functions are OK. Its just when the ignition is on. The pump gets very hot doing this. Fluid has been changed and has correct levels. Car raises up and down OK.

Any ideas?

[Guest Moonraker]

Hi

My C5 high pressure suspension pump runs all the time when ignition is on. The door opening and boot opening cause the normal 5seconds or so run and then cut off so those functions are OK. Its just when the ignition is on. The pump gets very hot doing this. Fluid has been changed and has correct levels. Car raises up and down OK.

Any ideas?

[Guest Moonraker]

one fault could be failure of 45amp relay which is available as a spare part but may be difficult to fit (I haven't done so, but it is in front o/s wheel arch. My garage take 2 hours to change the suspension HDI Unit.. It is an electric motor, hydraulic pump & Built-in "ECU" on top ( not the main ECU, just one of about 4). get price from garage before they start!

However, relays usually fail such that stay "off" all time, not "on" all time.

Note thet the 45Amp maxti fuse is under bonnet, down side of fuse-box, not visible unless you list out fuse box & careful not to short-out!

[Guest C5buff]

I have checked fuses and they are all OK. It seems to me that the BHI ECU is always demanding the pump to run whenever the Ignition is on. This is obviously incorrect as the pump is only meant to run for a few seconds at a time as required. I have temporarily got round the problem by fitting a switch in series with the command line into the pump. So I now control the running of the pump. This means I can now drive the car, I give the system a pressure top up every now and again.

The things that cause it to run would normally be the suspension hieght sensors, the up command switch from the driver, condition of the road surface needing the suspension to rise. The lowering does not need the pump as the electrovalves in the BHI simply dump fluid back to the reservior under the weight of the car. Closing again when the ECU senses the hieght is correct. All of which seem to function OK. I am thinking now that I have a faulty output from the BHI ECU as there are no faults logged on any of the computers including the BHI, in other words its something the BHI ECU does not know about. ( I have had the cars fault codes checked by my local garage who has kit that can read them and no faults were shown) I was quoted the cost of a new pump from Citoens as £875. The oil is £12 a litre plus VAT. These cars can be very demanding to maintain.

[Randombloke]

I was quoted the cost of a new pump from Citoens as £875. The oil is £12 a litre plus VAT. Thes cars can be very demanding to maintain.

 

Maybe you need to check some of these links, then:

 

BBA Reman Citroen section

 

C5 suspension pump - ask for quote

[Guest C5buff]

I will fight it a bit longer before I surrender to a new BHI. Wherever they come from they are going to be pricy. I have a running car with a pump that works and I have control over the run command with a switch.The BHI ECU is working the suspension correctly, so for now I can get by. In fact as well as the switch, I am now thinking about a 12v adjustable cyclical timer (cost about a tenner) in series with the run command with a 8 second or so run, every 10 minutes so I don't have to remember to do it myself thus conserving the pump. It has the disadvantage that should I want the suspension to rise using the up button it will not coincide with the 8 second run. So my original switch can still be used to bypass the timer and demand the pump to run for that purpose.

If I end up having to go to Citroen it will be with gritted teeth. We will see, I will keep the site posted. Thanks for the interest in this particular fault.

[Guest C5buff]

Further to the above, I have now fitted the timer in series with the run command to the pump. The power for it is taken from the ""ignition on wire" pin A4 going into the BHI ECU. Thus whenever I turn the ignition on, the timer switches the pump on for 10 seconds, enough time for the BHI ECU to read the hieght sensors and adjust the cars suspension as required. Thereafter the pump runs for 6 seconds every 15 to 20 minutes in order to maintain the pressure in the system. When the ignition is turned off the timer is turned off.

Now then suppose I needed to raise the car to the top hieght setting say to change a wheel. All I need do is turn on the ignition and press the up button to get a ten second pump run to lift the car.

So far its working well and should be reliable. However should the timer fail, it will fail safe and the pump won't run.

The cost of the timer which I ordered from the Web was less than a tenner incl VAT and delivery. All I needed after that was a couple of resistors to make the timer work over the time intervals I wanted, got them from Maplins less than a quid plus postage. I could not have done this without an Emanual as I was in need of a wiring diagram. Cost me a tenner to download. Big file 17Gigs. Their web page is eMANUALONLINE.com if anyone is interested.

[Guest c5r]

I am very impressed with your way of getting around your problem with the BHI constantly running. The problem I am having with my C5 is the opposite, the motor is not running at all. The suspension is now down and will not rise. There is no life whatsoever from the BHI unit, the charistic buzzing of the unit everytime the car is unlocked is missing and the ride hight buttons between the front seats has no effect.

I have been trying to narrow down the fault. The haynes manual for the car dosen't giving a wiring diagram for the unit. I have found 3 connectors to the unit, 1 is a multi-pin emc connector the 2nd is 2 heavy gauge wires which have 12 volt supply between them all the time which I am asuning is the supply to the motor and the 3rd is a single thinner wire. Is this single thin wire the command line you talk about? and does this wire need a 12volt signal to be present before the motor on the BHI operates? Does anyone know where I can get a wiring diagram for the unit

Regards

C5R

[Guest C5buff]

I am very impressed with your way of getting around your problem with the BHI constantly running. The problem I am having with my C5 is the opposite, the motor is not running at all. The suspension is now down and will not rise. There is no life whatsoever from the BHI unit, the charistic buzzing of the unit everytime the car is unlocked is missing and the ride hight buttons between the front seats has no effect.

I have been trying to narrow down the fault. The haynes manual for the car dosen't giving a wiring diagram for the unit. I have found 3 connectors to the unit, 1 is a multi-pin emc connector the 2nd is 2 heavy gauge wires which have 12 volt supply between them all the time which I am asuning is the supply to the motor and the 3rd is a single thinner wire. Is this single thin wire the command line you talk about? and does this wire need a 12volt signal to be present before the motor on the BHI operates? Does anyone know where I can get a wiring diagram for the unit

Regards

C5R

 

 

Hi

Yes the thin wire is the run command and has a signal 10V to 12V on it. The connector with two heavy duty wires supply the pump motor power, one pin has 12V on it and comes from the engine fuse box via 40A maxi fuse MF8 the other wire goes to chassis ground. Provided the fuse is ok 12V is always present on this connector all the while the battery is connected. The third multiway connector plugs into the BHI ECU and has inputs from the suspension height sensors, the BSI, the ABS and engine fuse box. The BHI ECU outputs the run command to the pump from pin F2 on this connector (the thin wire). Since your pump won't run you need to see what is missing. The 12V power or the run command. To do this just unplug the run command wire from the pump and check for voltage appearing on its contact pin when a door is opened or ignition switched on. If voltage signal present then OK. Next unplug the motor power plug and check for 12V on one pin, and also check that the other pin goes to chassis, BEING VERY CAREFUL not to short the two pins out. If both voltage checks are ok then the fault is in the motor electrics. If this is the case then it will probably be the transistor switch inside the plastic cover. It will I think be unlikely to be the motor itself. I obtained second hand pump from a chap on ebay for 40 quid. I removed the end cover off the motor where the connector is. Inside there is a plastic former with four carbon brushes mounted on it together with the transistor switch and a suppression capacitor. This assembly just pulls off the commutator of the motor and can then be refitted onto to the commutator of your pump motor. That would be a fix for that problem. If the run command itself is missing then the fault is in the BHI ECU, assuming its inputs are all ok and the ECU is itself ok. ie no error codes logged on cockpit display.

If it looks after all like the output run command from the ECU is duff (ECU in other respects ok) then a timer solution to switch your own 12V run command could be considered, similar to what I have done.

If you want wiring details these can be had from www.eMANUALONLINE.com

Download yourself a manual.

To get at the pump better you need to take the bumper off and the headlight. The bumper comes off quite easily, after you have done it once it can be done quickly the next time.

This will do for now see how you go. Well done for trying to do it yourself.

NB/ Do NOT disconnect the multiway connector from the BHI ECU at any time when the battery is connected or a fault will be logged on the BSI as it will think there is a major fault on the suspension which will require recovery to a garage to have the fault codes reset before you can drive the car.

I have given a link below to show the timer details.

 

 

Click here for diagram

[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.

[coastline taxis]

And thank you for getting back to us with the fix to the problem