X7 Break 3 2010 // Missing initiation signal on hydro-pneumatic system

[Coney]

Hi all,

My x7 break is at a shop where its AL4 was repaired. The guy at the shop is not a Citroen mechanic but rather an automatic transmission specialist.

When he went for a test drive during which the hydro-pneumatic suspension suddenly eased down to the bottom position and can since not be convinced to pull the belly up from the cold ground.

The only error to be found is from the hydractive system (U2005) claiming it's lacking a signal for the initiation of the suspension, and one usually hears the pump kick in as soon as one clicks the key to open the door. I suppose that's the missing signal.

He says, he's gone through all fuses and connections and all seems to be fine.


My question: has anyone ever experienced anything of that sort and remembers where the culprit was hiding?

Have a great day.

[mickthemaverick]

You may find a read through this thread will give you an idea of what you need to do: viewtopic.php?p=694559#p694559 Good luck

[Kees]

The U2005 is a ghost error, this one becomes from the diagbox.
What engine we talking about 2 or 4 cylinder?
Is there an error message on the dashboard?

[Kees]

Sorry, I understand now, AL4 is 4 cylinder, so if there is no error on the dashboard, there's possible a problem with the height sensor, because this one sits on the left side behind the gear box.
There is an lever on it with a little rod to the clamp on the balance rod.
It's possible this one is now in the wrong position.

[Coney]

Thanks @mickthemaverick and @Keeth,

everything is pointing towards the height sensor up front.

That is the region that has been worked on and since the state of the suspension changed from good to bad during the test drive, it is extraordinary likely that the rod has lost its proper position.

I just called the fellow at the shop (he actually was grateful ) and I'll know more on Monday.


Have a grand weekend and thanks again


Coney

P.S.: and, yes, it's a 2L 4cyl., 16V engine.

[Kees]

Its not the rod, this position is done with the lower control arms, but on this rod is an clamp with connection to the height sensor, so if you not notice this About the position or something else you can overstress this one, or put it in the wrong position.

[Coney]

Well, I'm not doing this myself (I'd be done by now). It's the guy at the shop who rebuilt the transmission.

Talked to him today. Says, he had replaced the height sensor over the weekend but then put the original back in when he discovered there was no voltage. He found 5 Volts up to the connector before the sensor - there it went cold.

Battery was down, he's charging it over night, so I should hear about the results tomorrow.

[Kees]

It's about the position of the lever on the sensor, look at the pictures!!

The position must be, like the yellow one.
About the voltage, this varias between 0.3 and around 4 volt.
The supply voltage is 5 V, so this is correct, but when the lever is in the wrong position the output signal could be almost 0V

[Kees]

I find the other pictures.

So you see the output voltage between the two positions.

[Coney]

Thanks a lot.

Just passed the information to the guy at the shop.

He seemed pretty confident that this is the error. There wasn't any voltage at all due to a bad connection. He fixed that and now has the 5 V at the sensor.

However, I did sense a little uncertainty between the lines.

Do you know where I could find detailed information about the adjustment process?

[KennyW]

Have look at this link https://frenchcarforum.co.uk/forum/view ... hp?t=70745 .

Any slight movements of the height sensor on the anti roll bar changes the suspension height quite dramatically.

I had great fun a few years back sorting my suspension but eventually got there.

Kenny

[Coney]

Update: from the frying pan into the fire

The guy at the shop replaced the front height sensor. The old sensor first didn't get its 5V due to a cold connection, that fixed, it revealed a resistance of 50 MegaOhm which suggests it was worn to the last filament, I guess.

The new sensor is in, he said, he had set up the suspension without any issues; he could raise and lower it, the entered values remain, yet the suspension does not receive its "cleared for takeoff" when the ignition is switched on.

His suspicion/diagnosis: while all other components (engine, transmission, etc.) receive a signal ("0") from the ABS velocity sensors, the signal doesn't reach the suspension unit.

So I'm looking for a diagram or a "pinout" of the 7715 Unit (suspension and power steering).

I stumbled upon a "list of diagrams" here in the forum and found the unit listed but there weren't any links to diagrams which I had expected.

Does anyone know where I could find one?

[Kees]

Look, there's nothing wrong with other things!!
The problem of your mechanic is he don't understand the system!!
First about the sensor, you can not measure the resistance, because the system is an hall sensor, so there are no components with make physical contact inside.
If the car wil not coming up to the ride height then the computer "think" the car is standing to high!! and the reason for this is the wrong position of the height sensor.
So don't look at something else!!
The picture i sent to you earlier i say about the yellow one, this is the right position, you can see a hole in this one, you can put a 5 mm pin in this position, then connect the rod with the stabilizer rod, this should be the correct position to start with then you can small adjustment with the clamp to correct the height of the the car around 37 cm from the ground to the middle of the arc from the front fender.

[Kees]

Here you are, point #2 from the height sensors are the signal for the height of the car and should be around 2V in the normal ride position.

[Coney]

Hi,

thanks for the information. I feared something like that. If that's a hall based sensor, he won't measure a reasonable resistance and I would expect that he can't have measured anything different after replacing the sensor.

And of course, it makes sense, if the entered data indicates a higher than reasonable position, the system won't raise it any higher.

Since the persisting "ghost", U2005, is due to the lack of velocity values while the car isn't moving and caused by the ECU setting it "0", then there can't actually be a missing "0", was a thought I had.


He knows about blocking the sensor with a 5mm rod. Since you said to block it in the above position, I take it, there isn't one corresponding hole but rather several possible positions.

He told me, he that he entered a distance from the ground to the highest point of the fender arch of 70 cm. That would be way too high since you're saying 37 cm which is about half that value.

These 37cm are a fictitious value and not an actually measured distance between ground and top of fender at that time, I would think.

And the suspension would at that point be in the lowest position, right? Or is this entered value (37cm) not at all depending on the suspension's position settings?

Sorry, I'm trying to learn this so I can tell him what to do, in order to get ma car back.

Thank you, have a nice day.