Has my x7 suspension dropped?

[Bandit12]

I've attached photo of my x7 estate (hopefully) and it looks like rear of car is sitting lower than front. Is this normal? Car is unladen and cycles through raising and lowering ok.

Is my car level?

[EDC5]

Either the back has dropped or the front is too high. I have had both happen to mine in the last year.

I corrected the front being too high by using lexia but had to manually adjust the height sensor for the rear, as it was driving with the back end fully in the air

[GiveMeABreak]

It does look a little low at the rear to me from the picture. Make sure it is supported independently first, then have a look under the rear and see if the height corrector is caked in rust. That whole area is a rust magnet including the rear accumulator spheres.

[Stickyfinger]

A mild steel dog bone does not help either

[GiveMeABreak]

Very true - On my second Height corrector and counting....

[Bandit12]

Thanks guys and I've had a quick look at the back end, no rust or anything obviously wrong with the rear ride height sensors/linkages. I cycled the car through the full up and down a few times and noticed that when I return it to the normal driving setting the rear dips down at the last minute to compensate. I therefore think the front is a tad too high so I'll put car on lexia and see what I can find.

[GiveMeABreak]

I still suspect the rear height corrector - they are prone to water ingress and can affect the signal / voltage sent, but also can simply wear out - this should help explain it:

Graph (4 Cylinder X7 Only) "A" Output voltage: Body height sensor . "B" Angle: Body height sensor . A negative value of the angle of the body height sensor corresponds to compression of the suspension. A positive value of the angle of the body height sensor corresponds to release of the suspension.	Height Corrector (4 Cylinder X7 Only) Water ingress at the connector or at the rotational joints can gradually cause issues.

There is a 3 way connector. It is a 5V supply and is an analogue signal.

So you can see that at 'normal' height at rest it should be sending 2.5 V, but if it is sending a slightly higher voltage, the suspension ECU will likely think the car is too low and raise it a little to compensate. So it may be at a particular part of the track - at rest (where it is most of the time) that is getting worn or has some corrosion.

Channel	Matching Track
1	Sensor Positive Supply
2	Body Height Sensor Signal
3	Sensor Negative Supply

[EDC5]

That is an excellent diagram Marc, very useful. Potentially any additional resistance along the wire (from poor or corroded connectors) could end up affecting the ride height then. Not an ideal situation.

I wish there was a way in lexia to see the raw voltage being read by the BHI rather than only having access to the 'steps' conversion.

Thinking back to when I had to adjust my rear height corrector. The sensor itself may have been fine but a poor connection along the wire somewhere could have caused the back to be fully in the air!

[GiveMeABreak]

Hi Elis - looks like it - simply the voltage level affects the height. These are deemed 'throw away' units like most things these days. I'm on my second one now after I had some issues with my directional headlights and then the occasional refusal to lower or raise on command. It was intermittent and as one expects, when it went into Citroen for a check it refused to misbehave

Finally after a few harsh words she decided she would play nice and replicate the behaviour - then they managed to catch it on Lexia - new height correctors front and rear and problems solved.

[EDC5]

Yes, you must be glad that they were replaced under warranty (if I remember correctly).

The procedure you sent me for replacing them looked like a nightmare for the front corrector; the subframe has to be lowered for access!
Not something I'd be up for doing unless absolutely necessary. The rear one is very easy to replace according to the document though.

In this case I'm surprised the height correctors are not part of the CAN system as the data they send would not be subject to the distortion that can occur on analogue sensing circuits.

[GiveMeABreak]

Yes CAN is very fault tolerant - but I suspect they only need a simple signal and as there is no ECU in the height correctors, there wouldn't be much point using CAN - but I suspect that had they redesigned it to have an ECU in there that the replacement would be in £100s!

[EDC5]

That's a very good point. I just think they should have used a more resilient system for communicating the body height to the ECU. Even a 4 wire (resistance) measurement system would eliminate a lot of potential error over the current system.

[GiveMeABreak]

Yes, I've noticed they do not really car much about waterproofing the connectors - evident by the exposed blocks where the wiring enters - I'm amazed there aren't more problems to be honest.

[Bandit12]

Thanks for the advice guys. I have cycled the car through full up and down with no issues or faults, I have also measured between hub and top of wheel arch and the front is 3 cm too high. This 3cm height difference remained on all suspension settings.
I have just hooked up lexia and encountered a host of issues. firstly it stays in diagbox v7.02 and does not open lexia is this normal? Diagbox seems to work fine and did a full diagnostic etc but how do I actually adjust the front height? All menus only give read only and I cannot find anywhere to make adjustments-very frustrating.
Would it be easier to put the front up on ramps and adjust the sensor clamp manually to reset the height?

Any advice is appreciated

Bandit

[GiveMeABreak]

Hi Bandit, yes Diagbox is used on the X7 as opposed to Lexia.

The values for the suspension are entered using the outcome of calculations from the specific measurements. Anything within about 10mm can be fine tuned in the height settings but more than this and it is a manual adjustment on the height corrector. But the front one is a bu**er to do given the location.

I would suspect that your height corrector track might be worn so it’s possible that even adjusting it might not solve it. I’m on my second set now.