C5 height sensors

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C5 height sensors

Post by C5 and P2 2-8-2 fan »

Evening all,

C5 exclusive 2006 (Facelift)

Having spent the last three days reading threads, diagnosing with Lexia and putting a new sensor on the rear height corrector I've run out of ideas so any suggestions welcome.

The problem is the car won't rise from the lowest position when the buttons pressed.
The pump will run on the Lexia 30 second test and after a BSI reset (last of several) I noticed today the lds tank was pressurised which it wasn't before.
All fuses are ok and I've cleaned all the connector blocks with switch cleaner but Lexia says no power supply to sensors and there may be intermittent communication problems with the abs ecu, bsi reset may have corrected these.
I don't have a wiring diagram so rather at a loss where to start looking now.

If it helps the earlier symptoms were a couple of weeks ago the directional headlights stopped working for a few days then started again of their own accord.

On the day of the failure the wife was driving on her own, the suspension fault warning came up three times briefly, each time was when the steering was being turned, don't know if this is significant, the last time was as she was turning into the drive so perhaps we were lucky in that respect.

Many thanks in advance for suggestions.
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Re: C5 height sensors

Post by GiveMeABreak »

First things first - you have Lexia, so when you have run a global test, what are the actual fault codes showing - this is essential information.

The Directional element of the headlights are dependent upon the Suspension ECU getting correct and coherent data from the height sensors. The fact that you have a suspension warning tells us there is an issue. It will of triggered a fault code as a consequence. Your headlamps will continue to work perfectly well - just without the directional function whilst there is a fault.

Pop the code (s) up and I'll take a look, along with your VIN so I know exactly what options you have.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi Marc,
I'll have to check for fault codes again in the morning, weather permitting, from memory the only one that came up was P05E0.

Dave
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Re: C5 height sensors

Post by Hell Razor5543 »

There is a clue in what you have said, in that the warning came up when the steering was operated. The LDS system is used by both the suspension and the power steering (if my memory is correct).

How is the LDS level (with the suspension fully bottomed out)? There are some slots in the neck grating in the reservoir, and the LDS level should be between the lower and upper slots (these are obvious when you take the cap off). If it is below these it could be worth topping the LDS back up.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi Hell,

Yes that was my thinking but the levels seem ok, I'll probably check again in the morning.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Just found this on youtube:



If the weather's not too bad will try in the morning and report back.
Last edited by myglaren on 14 Feb 2020, 23:31, edited 1 time in total.
Reason: video link
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi again,
Marc the vin is: VF7**************[VIN obfuscated, can be read by forum staff] rpo 10816
Faults are: P05D2 No comm. with steering angle sensor (Fault caused by another ecu)
PO5EO
In the lexia height correction field Height selector says high but dash screen will only show low.
Sensor supply 5v present.
The actuator tests wouldn't raise front or rear.

Have dismantled the engine bay fusebox as in video, no burning or corrosion, cleaned all the small fuse contacts and multi pin plugs but still no joy.
I am inclining towards a dodgy connection somewhere, too much to hope it could be a simple bad earth?, but the weather is starting to deteriorate so will have to leave it for now.
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Re: C5 height sensors

Post by GiveMeABreak »

Ok, so you can generally ignore the first fault - P05D2 or U1205 is caused when the suspension ECU is interrogated, as long as there is no warning on the dash and no other related fault code.

P05E0 is a permanent Fault: No communication with the steering wheel angle sensor incorrect value received.

So you need to ascertain if the electric pump is operating or not (but be careful not to operate it for too long so it doesn't overheat. How has this come about - just from driving? Has any work been done on the system lately? If the vehicle has had the hydraulic fluid drained and refilled then the tank needs a little pressure 0.5 Bar to help it get going. But this would not normally happen on it's own unless there is or has been a hydraulic fluid leak.

Check to make sure there is no puddle of hydraulic oil anywhere under the car if possible - but if it's stuck in low this may now be difficult - but don't get under without it being independently supported - as there is a risk of it rapidly depressurising completely and therefore a very real crush risk.

Check the fluid level as the car is currently at lowest setting I assume - it should be between 'A' and 'B':
LDS MK II.PNG
So if the pump is operating, there is fluid and you have applied a little pressure to the tank and it is still not raising, then we have to suspect the BHI (Basic Hydraulic Interface) as being faulty or the front / rear or both rigidity regulators:
C5 II Rigidity Blocks.PNG
Although I would think it highly unlikely for both of these to go at the same time (which would cause the fluid to return directly back to the LDS tank).

If it was one or more of the height correctors, I would expect a fault to say the data is invalid.

So check the fluid levels so we can determine if there is a leak and then look near the power steering electro pump to see if there is a leak anywhere.

Just to confirm - you say you replaced the rear height corrector - was it only the rear not rising or the front and rear?
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Hi,
No work has been done recently and as far as I can see there are no leaks, when I jacked the car up to change the rear corrector and then lowered it again this filled the reservoir up to the top so no shortage of fluid, I had hoped to change the front one as well but that will have to wait until the weather improves, not sure if this will make a difference anyway.
When the wife arrived home she told me the suspension warning had come up three times, each time when turning the steering, but had then gone off and the car drove ok. I went out to have a look and started it to try and raise or lower it on the buttons but it would only go flat to the bottom and not rise.
The pump doesn't run when opening the driver's door nor would either end rise with lexia function test.
It seems to me that the suspension ecu isn't getting a signal to tell it what to do, or if is it isn't acting upon it, why not is the question.

Just a thought, when it stops raining I'll check there is a voltage on the supply to the F8 maxi fuse.
Dave
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Re: C5 height sensors

Post by GiveMeABreak »

The motor only operates when it needs to so it won’t always operate when the door opens. It depends on what the height is as to whether it needs to pressurise any.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Just a quick update, checked and there is 13v on the purple wire to the pump so not the problem, the pump sounded quite smooth when run from the lexia.
The laptop I use for lexia is an ancient Toshiba run from the charger but today it would only start and shut down repeatedly so have ordered a new battery but won't be able to do any diagnostics until it arrives.
Previously when I tried the actuator tests neither front or rear would rise, I don't think the hard /soft change worked either (couldn't hear the valves moving) but the light came on/off, took the console switch out and cleaned it, seems ok, the dash display flickered when the buttons were pressed.
In view of this will now try and get the front as high as I can with a jack and stands to change the front height corrector, if no joy then it will probably be a case of draining lds and removing the tank to get to the ecu. Watch this space.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Continuing this saga, I managed to get the front on axle stands with a bit of a struggle and put the new corrector on, which raises another question: how to get the dog bone clipped on with the setting pin in place? Do you slacken off the clamp on the anti roll bar or clip the link on before bolting the corrector in place, tried this but then almost impossible to get the positioning lug into the hole in the cross member with the securing bolt slackened, too dark to work now so will have another go in the morning.

As the corrector was connected electrically with the setting pin in place I started the car with the same result as before so it's looking like the ecu is at fault.
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Re: C5 height sensors

Post by C5 and P2 2-8-2 fan »

Just checked the Haynes manual seems the locking pin is removed to connect the dogbone link,doh.
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Re: C5 height sensors

Post by lcwin »

hi when you replace the height sensor did you removed or lossen the link to the anti roll bar?
I fiddle with the height corrector before and when I start the car the up down height adjustment cannot function. What I did is use Lexia to depressurise the suspension and then it works fine. Give it a try.
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Re: C5 height sensors

Post by GiveMeABreak »

Don't move or adjust the clamp on the ARB / fixing or you will muck up the height settings when you do resolve the issue later. The slightest movement of the clamp will result in a height adjustment - but there should be no need to move these as they are set at the factory.

Best to leave it until you get your Lexia and then run a full Global Test and report back with the codes.

Depressurising the system doesn't have anything to do with the height correctors apart from move the lever connected to the potentiometer as the car raises and lowers. The depressurisation will just operate the hydraulic block valves.

When you said previously that after lowering the car after changing the rear corrector that the LDS tank was full to the top - what height was the car at? The fluid should only be between those marks in my diagram on the lowest height setting / when depressurised. If it was full at any other height then the system has been over-filled.