Strange one this. The EAS operates normally, or so I believe, but if I park on a slope with the left side of the vehicle lower than the right the EAS system seems to do its hourly assessment and lowers the left front suspension down a bit . . . each and every hour until it is at access height or thereabouts but never sets it all the way down onto the bump stops. It also then starts trying to level the rest of the vehicle on the hour, every hour but never lets the vehicle get down on the bump stops.

I'm convinced it's not a leak because a) it never does it if parked on the level - it remains as parked for days with n'er a movement in the suspension; b) you can hear the EAS controller operating the valve block when it does its wake up call lowering the vehicle; and c) it never does it if the right hand side is on the downsdie of a slope.

I am at a loss to explain it and can only think the front left height sensor must be playing tricks but when on the move it all operates correctly between the various ride heights!

Anyone able to shed light on this odd behaviour?

Have you got diagnostics? When the EAS self levels it lowers 3 corners to match the height of the lowest corner. So if parked on a slope so the left front is down, it should just lower the other corners and leave that one where it is. Unless of course, you have an iffy section of the track on that, or the right front, sensor.

Why the right front sensor possibly iffy? I think I understand the EAS operation but what is foxing me is that it is letting down the front left which is the one under most compression when on the downside of a slope (so should be lower than the front right). I exit the vehicle so, as expected, the right side suspension raises very slightly as my weight is taken off. Why then does it start to lower the left front as it should already be lower than the right front and continue to do so when any levelling has taken place and why does it stop its self levelling antics before the bump stops are reached?

The height reading via Nanocom all look OK when the vehicle is commanded to the various heights so I'm not seeing anything obviously iffy with any height sensor?

When sensors start to fail, they tend to under read. So with the left side down, the right side will be slightly higher but if that sensor is under reading due to a dead spot at that precise height, the system will think it is lower than it actually is. That will make it lower the other 3 corners, including the front left. Try parking it at a different height setting, High or Motorway, and see if it does the same thing. A small dead spot doesn't normally affect things as there is sufficient movement that it 'skips' over that point so the ECU ignores the brief erroneous readings.

I have parked at different height settings and it's made no difference. Copious use of soapy water on air lines and air bags has not revealed anything.

I have decided to start with the front left air bag and have disconnected the air line from both the valve block and the air bag, cut a few mm off each end, applied the pencil sharpener treatment to both ends and reinstalled. It has now been left at 'high' for two hours and precise measurement of all four corners reveals absolutely no movement of the suspension . . . .so far! I'm not convinced it is sorted but I will leave it for the rest of the day and see if there is any movement.

Next step will be the same treatment for the front right before removing the valve block and giving both front solenoids a good going over.

24 hrs later and the suspension has not moved one iota - not a single mm at any of the corners. From this I take it that neither the air bags nor the air lines to them have any leaks. It is not on level ground with a slight slope down from back to front (with the right sided sloping more) and a slight slope from left to right at the rear and a more significant slope from left to right at the front.

I unlocked the vehicle to retrieve a pair of sunglasses and on re-locking the EAS springs into action with the chattering of solenoids and exhaust noises and on completion of the exercise the right rear (which was previously the lowest) ends up 18mm lower, the right rear (which was the highest) 25mm lower, the right front has lowered 12mm and the left front lowered by 10mm!

I know from previous experience that if I leave it on level ground it sits nice and level and does not do any 'jigging' if it is unlocked/locked/opened/closed.

I cannot fathom this behaviour at all!

Further update. Vehicle has not changed height for last 2.5 hrs. I unlocked the car, opened the door, shut it and re locked and . . . nothing, it didn’t do its little dance.

When I shut down the engine at the beginning of these ‘tests’ I waited until the air tank was fully charged and the compressor had shut off. To check the air tank I fired up the engine and checked the compressor but it didn’t run at all so I let it down to ‘access’ height then banged the EAS back up to ‘High’ height and up she went immediately so no problem with air tank pressure. I conclude from this that the air tank and associated air lines are leak free and that all the valve block solenoids are OK.

Back down to ‘access’ level and then to ‘standard’ height. All OK, compressor fired up, replenished the air tank and then shut off.

It all seems to be working but I still don’t understand why it does its ‘random’ little dance occasionally and why it doesn’t just adjust to the lowest corner level when it does!

I can’t believe the control unit has self modified its programming so it must be the height sensors, must it? Or is the programming not clever enough to deal with slopes where each corner is very different?

Perhaps (once parked) replace the height sensors with resistors temporarily? See if the parked behaviour changes?Poor carbon tracks on the pots or just elderly wiring/connections could easily cause this behaviour (and the chances of the sensors/wiring being faultless must be fairly low).

The self-levelling adjusts based on sensor readings, not the actual height, so it does depend on what's programmed. Are the left-right values in the ECU Targets the same ?

The wake-up triggers are in the EAS System Info ducument.

DOOR OPEN “WAKE-UP”The system “wakes up” as soon as any door is opened. After all doors are closed, system
leveling could take place if any height sensors actual value differs from its target value by
more than ± 2 bits. The target value is determined by the lowest sensor input. If all the doors
are then closed, the delay relay will time out in twenty seconds. Height changes are inhibited
when any door (or tailgate on NRR) is open, up to a speed of 35 mph.

ENGINE RUNNING “WAKE-UP”
When the ignition key is turned to position II, the ECU wakes up again and another leveling
could be required. On New Range Rover all warning lights are illuminated to indicate power
without ECU activity, on Classic the lights illuminate at engine start. The system becomes
active when the engine is started and the ECU receives an rpm signal greater than 500 rpm.
The ECU will close the compressor relay and attempt to pressurize the reservoir. This
attempt will take place if the pressure switch is open, the thermal switch is closed and the
system is not trying to exhaust any air. Remember that air cannot enter and leave the
system at the same time.

Remember that air cannot enter and leave the
system at the same time.

Yep, I have to hold my breath to fart as well

Thanks for the info. Where might I find the EAS System Info document you speak of?

There are further clues in the RAVE Electrical Troubleshooting Manual under section S1 where it states:

" To compensate for any changes in load after parking (e.g. driver or passenger getting out), the EAS system will lower the vehicle to the height of the lowest corner after the last door is closed. Furthermore, if the vehicle should develop a lean due to temperature effects or air leakage whilst parked, the EAS system is automatically re-powered every few hours to allow limited corrections to the height to be achieved."

This explains the little dance it does when I exit the vehicle. I suppose it is feasible that the actual settings in the system are quite different at each corner to achieve the same actual suspension height and why the supposed lowest corner is not the lowest value in the system! I should get Nanocom out and check what the settings in the EAS at each corner actually are! The temperature effects could also explain why, with no leaks, it does regular little dances when parked - probably more common if the sun is out and warming up one side of the vehicle more than the other!

This damn system is far too clever for its own good!

'Tis here https://drive.google.com/file/d/1eHSEP_2OsOFxYZh-MgevIVRsDg5Tel2u/view?usp=drive_link

This one is also useful https://drive.google.com/file/d/1PK5oMkoJ89oDyhTkzcw9dbcL3ObFBVfQ/view?usp=drive_link

Ideally the left-right targets for each height setting should be within 2 bits of each other. Otherwise the front tends to dance when you stop at traffic lights !! Front-Rear doesn't need to match, but they should be sensible for each height so the car is level when empty of people & luggage with doors closed.

The saga continues . . .

I took Rangie to Dorset for a few days getaway. On a local journey the EAS faulted with quite a coarse rumbling sound but still had air in the bags so a swift stop and removal of the under seat control relay froze the system and enabled the trip to continue with no more rumbling and return home.

Cleared the fault (a non descriptive fault on NanoCom!), fired up the system and it was clear the compressor was in trouble. Swapped it out for spare (which still worked but had yet to refurbished) and normality was restored. Disassembled the compressor to find that it had broken the con rod. This is the second compressor that has done this, both having been refurbished a number of times. From this I conclude that the compressors only withstand a couple of rebuilds before they truly life expire. I bit the bullet and bought a new compressor and fitted it so I still have one to refurbish. All OK.

I have just returned from the Lake District after another getaway and half way home, over 1000 miles since the last EAS problem, the EAS hard faulted without any notice and immediately dropped onto the bump stops. I feared the new compressor had gone AWOL and had to nurse Rangie some 100 miles home on the bump stops - good job I replaced them all a few years ago! Anyway it was an ‘interesting’ journey and managed over 20mpg for that (or any) journey the first time ever. I thought the bump stops would be trashed but they remained in very good order!

I broke out the NanoCom again and, yet again, it just gave a non description of invalid fault or some such. I cleared it and the compressor fired up and filled the reservoir in a very short period of time so no compressor problem, indeed there must still have been air in the reservoir! The suspension went up and down on command and, in short, I cannot identify a problem. There appears to be no leaks and I have conducted a couple of journeys involving height changes including extended and lowering to access height and back up. It all seems to be working OK - I am perplexed to say the least.

I am beginning to suspect a dodgy height sensor - could that possibly be the cause? Any help appreciated.

I would too. Use the Nanocom to display the live readings from the height sensors then switch between heights while watching the readings. You are looking for one that doesn't rise and fall progressively but jumps.

I think that it's likely down to poor handling of error conditions by the EAS ECU. It gets a glitch with a height sensor giving an impossible reading & so loses its marbles which is why there is a fault with no valid error code. You can get a similar phenomenon with the ABS ECU when a wheel speed sensor throws an out of range reading. If the error handling was more robust it would be able to ignore the odd spurious reading.

So, I have been switching heights up and down, and down and up, and up and down etc., etc. whilst watching the actual readings like the proverbial hawk. There are no glitches/jumps, it all looks smooth and progressive! I dare say I have now expired 50% of the compressor life!

I have been driving around with zero problems for the last few days as well.

I am now reduced to ‘gut feeling’ and I am ‘blaming’ the front near side height sensor as I once, some time ago, registered an out of range fault on that sensor and it seems to be the most jittery when I exit the vehicle and it attempts to re-level.

Next question - best place/make to procure a front height sensor?’

I would go for a used original, front ones are easy to remove without damage so there should be plenty about. Don't get a Eurospares one, I bought two and both had failed within 3 weeks and 800 miles. There another brand that has recently appeared, ProEvo+, but no idea what they are like.

I'm not convinced used original is the way to go - risk of frying pan and fire seems high!

Two further questions for those more knowledgeable than I:

1. The front height sensors are not handed so if they are swapped do they then 'wipe' a different part of the internal resistance track or is swapping fraught with other problems?

2. I have come across Aerosus who seem to be pretty comprehensive across the automotive air suspension spares supply who do have the front height sensors listed. Does anyone have any knowledge about this outfit and its products?

I work on the principle that they wear out with use, so any used ones will have had less use than mine (553,000 miles and counting)! However, yes, you can swap them side to side and use a different part of the track. What you may find though is that is the dodgy part of the track coincided with the car at Standard height, it will now be at Motorway height or vice versa.

I have also seen the Aerosus units but don't know of anyone that has tried them so have no idea if they are any good or not.