Citroen C5 height sensor

[landyman]

Edit: for got to say it's a c5 2.2HDi 2002

I had a problem with the car, the suspension would be fine but occasionally and more and more frequently the rear suspension would pump fully up as I was driving and get very bumpy, after 5 minutes or so it would correct itself for a while and then maybe happen again. The citroen dealer and logic pointed to the suspension height sensor.
I did a quick search and people seemed to have rigged them up to test them but not fix them so I decided to have a go.
The sensor is located near the roll bar. The suspension needs to be put full up then the car needs to be securely supported (if it falls on you it could hurt)
Once this is done the dog bone can be levered off (looks less likely to break at the roll bar end as the other end has some plastic nearby).
The single bolt may require release oil and the electrics connection has a tab to release it.
Once off I removed the opaque plastic cover (white) by cutting through the glue holding it on using a stanley knife (carefully). If you are careful there are some alignment features which will help you get it back on again.

the sensor is not as I found on the web a rheostat (like a volume control) it's a much more complex and all together more reliable design with the position sensed via a coupling from rotor to PCB.

at the far end of the above picture you can see the weak point. There are 3 terminal posts that come off the connector and stick through the PCB. They are of a square peg in a round hole design and probably make contact quite well until they have been there for a long time.

the board can be removed to give it a clean with electrical contact cleaner (IPA) as below (scroll the picture down)

the contacts also appear to stop the board from moving, the gap between the board and the moving rotor is critical and the board should be pushed carefully but firmly back onto the connector pins so the gap is as intended. I then soldered the pins to the board which is very easy, guarantees contact and guarantees the gap (don't know why it wasn't done to start with).

Glue the opaque cover back on to the sensor making sure to get a continuous bead of areldite all the way around so as to make it completely water tight.

When you put it back on it's possible to fit the dog bone in 2 positions, high and low. If you fit it in the wrong one you confuse the suspension and it will keep pumping up and down. The correct position is to install it low.

I've not had any problems since I did it. May take it off again and wipe some silicon sealant around the join to make sure it's a proper job


Al

[oneday]

a very useful bit of info for the future

[Walt]

Hi landyman.
Realise this is an old post. But are the photos still available. I don't seem to be able to open.
Regards

[GiveMeABreak]

I will look into this to see if the images are still available.

[Walt]

Thanks Mark. Back end sensor suspected faulty, even though Lexia says no fault.
Ideally would like to remove and investigate.

[GiveMeABreak]

Walt - it is possible you won't get a fault, because they are analogue sensors - so all you will get are the height data in Lexia if you look there. There is no separate ECU for the height sensors, so there won't be any specific codes returned for the sensors for faults - only an anomaly if the height data is out of kilter possibly.

[EDC5]

^ This is a fundamental issue with the Hydractive system in my view. There really should be a sanity checking function or double redundant height correcting sensors (like the accelerator pedal has).

I've seen a number of C5's driving around either too high or too low with the driver oblivious to the issue.

[GiveMeABreak]

'Seat of the Pants' sensors - Literally.

[Paul-R]

Hope you can find the photos Marc, I'd like to see them as well.

[xantia_v6]

I am looking into the missing pictures, but I don't yet understand when they were added to the post. The original post dates from 2013, but we did not enable the upload of images to this forum until 2017... The forum database says that there were uploaded at some point (probably in September 2018), but the image files are not found on the server.

[dnsey]

Perhaps it's a figment of my imagination, but wasn't there a forum glitch a while ago which resulted in the loss of uploaded posts and images for a day or so?

[Paul-R]

That was probably following the Great Photobucket Debacle when they started charging for displaying stored pictures on web sites. IIRC FCF encouraged people to upload here the photos that were now blocked.

[xantia_v6]

Perhaps it's a figment of my imagination, but wasn't there a forum glitch a while ago which resulted in the loss of uploaded posts and images for a day or so?

It appears that you are correct (nothing to do with photobucket this time).

It seems that the post was edited and the attachments added (I am not sure whether by the original poster or an admin) on the day of a major software upgrade, and there seems to be a period of about 8 hours where uploaded image files are missing. It must have been my mistake, but the files are not in our backups. Maybe the original poster still has them.

[Paul-R]

...nothing to do with photobucket this time...

Mmmm, but would the OP have been prompted to do the uploading if Photobucket hadn't gone stupid? So it was Photobucket's fault in the final analysis.