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Pauliebanger
Member Since: 23 Jun 2023
Location: Lincoln
Posts: 25
  
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| Suspension Fault. Only Normal Ride Height Available. |
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Hello,
Having broken my right arm 4 weeks ago my Discovery 4 2013 has been standing on my drive unused.
I managed to drive it for a few miles yesterday and during which the ‘Suspension Fault’ message appeared. Mental note ‘I’ll sort this out when my arm’s better’.
This morning, however, the car has dropped to Access Height or maybe even to bump stops as the ride is now quite ‘choppy’. So I’m trying to diagnose the problem, but restricted by my fracture to only light duty work for now.
I have a GAP tool and there are three fault codes recorded.
On the RLM-Suspension page:
C1131-92 – Air supply – Component failure - performance or incorrect operation (68)
C1A20 – 64 – Pressure increases too slow when filling reservoir – Algorithm based failure – signal plausibility failure (AB)
And on ABS-Brake Module:
U0421-68 – Invalid data received from ride level control module – Algorithm based failure – event information (2B)
I looked at some live data and noted that whilst the power supply to all four height sensors was identical, at 4.90V, their output voltages varied. Front left and rear right indicated only 1.55v and 1.43v respectively whilst front right and rear left returned 3.48v and 3.55v. Same anomalous results after driving for 400 metres.
The only physical check I’ve been able to make so far was to remove the suspension relay (R7) and short the large connectors to energise the pump circuit. The pump ran under these conditions but I can’t comment one way or other on its relative performance. No change in suspension height was observed during this brief test. To eliminate the possibility of a failed relay, I substituted the identical relay type from the adjacent heated screen circuit. This did not result in the suspension issues being removed.*
It would seem that the problem arises either in the loom or its connectors or failure of sensors or suspension control module.
I would be grateful for any insights regarding the fault codes and live data reported above and if I’m on the right track with my thinking, please.
I would also welcome suggestions/guidance as to how and where I can begin to investigate these possible causes.
Best regards,
Paul
* tonight, as it was quiet, I removed the fault codes and manipulated the suspension switch. The pump ran for 11 seconds at which point the Suspension Fault message reappeared and the pump stopped. Suspension did not move at all.
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 10th Sep 2024 8:40 pm |
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skunk38
Member Since: 05 Jan 2024
Location: South Wales
Posts: 115
  
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Is the Battery voltage ok?
I had similar codes on my D3 recently when the weather got wetter and lower temp, only to find the exhaust valve on the compressor (AMK) was sticking due to being 'furred' up with white alloy corrosion and moisture behind it.
I stripped it all down, fitted new seals and desiccant and now it works as it should.
It could be a different issue on yours, but an idea to start with maybe? 
I hope you're arm is feeling better soon. Volunteer driver with 4x4 Response South East Wales
Volunteer Rider for Blood Bikes Wales
Land Rovers owned -
Disco 1 - 300 Tdi - dead
Disco 1 - 200 series - 3.5 V8 on LPG - dead
Disco 2 - TD5 - sold
Disco 1 - 300 series - 3.9 V8 on LPG - sold
Disco 3 - TDV6 HSE - current
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| 11th Sep 2024 8:38 am |
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Pauliebanger
Member Since: 23 Jun 2023
Location: Lincoln
Posts: 25
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Just back from a consultation at the fracture clinic - arm is healing quicker than expected, so that's good news.
The verticle distance from wheel centres to wheel arch is only 410mm at each wheel, so it's sitting much lower than Access Height.
The vehicle battery is only 3 months old and I have confirmed that is fully charged.
I don't yet know which type of pump is fitted to my vehicle (can I get that info from the VIN?) but the suggestion of a sticking valve would fit the fault code criteria so I'll be checking that out, thank you.
Unfortunately, there are quite a few valves in the whole suspension circuit. Anyone know if it's possible to narrow the possibilities down using data from the GAP tool? If so, any guidance on what's required would be gratefull received.
Paul
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| 11th Sep 2024 5:34 pm |
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Pauliebanger
Member Since: 23 Jun 2023
Location: Lincoln
Posts: 25
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Following suggestions in another thread of mine, I decided to replace the air supply unt (compressor).
I found that AMK type was appropraite for my VIN, but had a peek inside the cover to confirm.
Removal of the old unit and subsequent fitting of the new was very straightforward.
Suspension now adjusts from 'Bump' to 'super extended' and the system is holding air.
I've cleared all DTCs and none have returned.
I am using the car in Normal ride height which is fine, for now.
BUT, there is a residual problem.
When lowering the suspension from Off Road to Normal, or Normal to Access mode, the front suspension drops quickly to the correct height whilst the rear drops more gently.
As the rear gets to the correct height, the message 'Extended Mode Engaged (or something similar) and the suspension raises to the extended mode and I am advised to select an appropriate ride height once the obstruction is cleared. There is no obstuction - clear air underneath on a tarmac driveway.
If stationary, this up/down nonsense continues. If the vehicle is moving within the respective speed ranges when a lower height is requested Access, Normal or Off Road modes are successfully selected and the suspension self levels as it should.
There are no DTCs revealed by the IID tool.
In order to access the compressor for removal and replacement, I jacked up the car quite high at the rear and placed axle stands under the chassis.
When the new compresssor was in place and with the engine running I got the 'extended' message. I put my foot on the brake whilst holding the EAS botton in the Up position for more than 3 seconds to get to the super extended height and I was able to remove the axle stands without further jacking required.
On selecting normal height, the down/up saga began.
I understand how the extended/additional height (super extended) system operates and its purpose, but I don't know how to 'convince' the suspension that when the vehicle is actually at normal ride height the message 'extended height' in the dash screen is incorrect.
My initial thoughts suggest that maybe one or more of the the height sensors is operating out of range, but there are no DTCs showing. Selecting and maintaining normal ride height when moving is possible too.
Anyone offer any relevant thoughts or suggestions on what my next action should be to resolve this anomaly, please?
Best regards,
Paul
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| 27th Sep 2024 9:15 pm |
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greydisco
Member Since: 23 Dec 2021
Location: mon
Posts: 2
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front moving down first is normal to avoid blinding people with headlights. if the problem crops up when the rear starts to go down it could be the car detecting an obstruction. this is intended to stop the vehicle landing on a rock. happened on mine when the rubber gaitor on one of the rear units trapped itself under the metal outer sheath of the air suspension unit. it was an absolute pig to remove and ended with cutting away piece by piece and repalcing with new.
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| 3rd Oct 2024 6:45 am |
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itsaguything
Member Since: 20 Dec 2023
Location: Manotick, On
Posts: 256
  
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Firstly, do you have a copy of the workshop manual?
Secondly, please provide empirical data. What do you mean by “battery is fully charged”?
With the maintenance procedures, we could merely be in a situation where a “calibration” is required.
But frankly, I would be following the established procedures for identifying root cause: the pinpoint tests.
First pinpoint test in these matters is confirming the good condition of the electrical source.
Once we have passed that hurdle, only then are we on to the next test. 2015 LR4 HSE Lux Aintree Green
2013 LR2 HSE Radiance Red
2007 XKR Jaguar Racing Green
2005 XJR Jaguar Racing Green
2002 S-Type R British Racing Green
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| 3rd Oct 2024 10:46 am |
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Pauliebanger
Member Since: 23 Jun 2023
Location: Lincoln
Posts: 25
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greydisco wrote:front moving down first is normal to avoid blinding people with headlights. if the problem crops up when the rear starts to go down it could be the car detecting an obstruction. this is intended to stop the vehicle landing on a rock. happened on mine when the rubber gaitor on one of the rear units trapped itself under the metal outer sheath of the air suspension unit. it was an absolute pig to remove and ended with cutting away piece by piece and repalcing with new.
Greydisco,
Thank you for your response.
In the light of your experience I just checked these gaitors. They are positioned correctly and are operating normally.
That's at least eliminated one of the possible causes in my case, so thanks for telling about the cause of your problem.
Best regards
Paul
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| 3rd Oct 2024 12:16 pm |
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