Getting the X350 ready to hand over to my stepson.
It has been up on a hoist in my garge while we removed the ZF and had it overhauled.
Today lowered the car to the floor while on the hoist and the back suspension looks up to max height, front is down at minimum.
Running the engine for 10 minutes did not raise the front.
Instrument cluster warns "CAR LOW"".

History: Car is early VIN 2003, just over 150,000km and was daily driver.
Over the last few years if the car is not driven for a week or so get the "CAR LOW" message for a few minutes until the suspension pumps up.
So a progressivly worse leak, and it did seem all 4 corners were low.
Now we have the front low, but rear high, and no sign of anything happening,
Looked up the sticky note on the air suspension, excellent info but lots of detail to absorb.
Before going on anybody have a "most likely" suggestion.

Stepson is champing at the bit to show off this fine car.

 

When things like that happen I 'plug-in' my IDS and command the suspension LOW and then command it back up.
Maybe disconnect the battery for a 'hard-reset'?

Not sure if letting ALL the air out of the suspension will get the compressor to get it level again?

I have no suggestions to deal with the car without WDS, IDS etc.

 

Have you tried moving the vehicle at all?
Moving the vehicle when things are setting too low.
Should start the compressor, to inflate the shocks.

 

Thanks for feedback.
First problem is the low front means the car will not clear the two front arms of the two post hoist.
No chance to get a jack under there, but looks like I can get a piece of timber under the car next to the jacking point and easit it up enough to release the arms.

Second problem is a pronounced dip at the end of the driveway where it meets the road. I cannot get it over that dip unless the suspension is about 80% up to normal, and we are a long way from 80% at the front. I have room to drive back and forth about 4 car lengths before the dip. I can give that a try to enable the compressor. I am not sure why the car must be moving for that, it makes more sense for engine running to start the compressor cycle.

I will raise the car again and make sure there iks nothing obviously wrong with height sensor wiring or location at the front. I will order a comprssor fix kit.

 

. That was my first thought. Guessing that there may be an interlock switch requiring the gear selector be in drive to activate.

 

I've just been through it. Front drops after a few days. Usually jacks up with idle in the level garage for 20 seconds, but last time did not until I drove it to the gate.

I ordered a new compressor from RMT in Florida. US-$195 plus $85 shipping. Arrived on our island off Auckland in 7 days. No GST charged, no halt at the border.

At that price, and comments from others that RMT sells a good unit, I reckoned it was a better idea than buying a rebuild kit. I was going to install it myself, but the local indy shop that Jaguar sends all their older car customers to said they could do it in an hour and they did. Since I have read about breaking mounting bolts, I figured it was better to have them do it.

There are two ways of owning old cars... fix when things break - on their schedule, or replace parts known to break on my schedule. My 2004 XJ6 went into limp mode when I was 400 km away from home on Christmas Eve morning. I found a shop in Taupo willing to stay open for me, but it was an expensive bill and a bit of a drag when the family is doing Christmas things in the mountains. Next time it went into limp mode was Easter Friday when the left rear air spring blew out. Luckily this time, it did it in town and I had a spare air spring at home, so was able to replace it the next day. Now I am moving into proactive mode, asking members of this forum about the things that tend to fail on X350s so I can find affordable parts and schedule when they get installed.

So my advice is to order the compressor from RMT and replace it without bothering to determine if it is the source of the leak or not. If it cures it, then order the repair kit, rebuild the old one and put it on the shelf.

 

Is the hood closed?

 

Here is some info from a student training guide for the air suspension that may be relevant. Bear in mind that the compressor only operates for 2 mins to protect itself from overheating. I would first start by making sure the compressor is activating when you start the car. You should be able to hear it in front of the left front wheel behind the inner fender liner when the car is first started. You may have to actually drive the car a bit if the compressor cannot completely supply the reservoir at start up.

I also do not remember off the top of my head if '03 is when they started only using one height sensor up front. If so, and if one of the front struts is struggling, it will affect how both sides look.

Should the vehicle require raising, then the system utilizes the reserve air supply contained within the reservoir if below 25 m.p.h. (40 km/h).
However if the reservoir is unable to supply demand then in extreme cases the compressor will be activated, i.e. Vehicle Too Low.
In normal circumstances the compressor only operates at vehicle speeds above 25 m.p.h. (40 km/h). Below this speed threshold the residual pressure held in the reservoir is utilized.
If reservoir pressure is insufficient then the levelling action is inhibited until the vehicle speed of 25 m.p.h. (40 km/h) is acquired.
At this point the air compressor will raise the vehicle and then the reservoir will be replenished once vehicle levelling has been completed.

 

[QUOTE=jluvzcarz;2388533]Here is some info from a student training guide for the air suspension that may be relevant. Bear in mind that the compressor only operates for 2 mins to protect itself from overheating. I would first start by making sure the compressor is activating when you start the car. You should be able to hear it in front of the left front wheel behind the inner fender liner when the car is first started. You may have to actually drive the car a bit if the compressor cannot completely supply the reservoir at start up.

I also do not remember off the top of my head if '03 is when they started only using one height sensor up front. If so, and if one of the front struts is struggling, it will affect how both sides look.

Thanks for info
Plan of attack for today:
Raise car on hoist again and check front suspension sensor wiring and brackets etc. are good.
( No reason they should not be, but will make sure ).
Lower car again and hopefully get it off the two front hoist arms.
Then I can drive it back out of the garage.
Now we may have a problem, because the front suspension bottomed out will probably chew up the front of the car as I drive it over the dip at the end of the driveway
In the driveway + garage space I only have 4 car lengths to reach 25mph.

Before trying that maybe starting the car and running in drive while raised slightly on the hoist will fool the system into thinking we are at 25mph.
That does not tick all the boxes this complex system might require. The fact that the car body is not compressing the suspension might befuddle the software.

I am still baffled at the low front suspension problem. Over the last 4 months the car has been up on the hoist for many weeks on end 2 or 3 times while we dealt with the ZF overhaul.
On lowering from the hoist up until now we had a "low car" message but still enough height to get out of the driveway. What changed ?

 

When you lower the car don't let it sit completely flat on the floor. Let the the tire touch but stop at a height that the car would look normal if it were full. Then start the car.

There is no reason for this thought process other than if you go to Bilsteins website and look up the process for installing new struts this is actually how they tell you to do it. They have specific measurements that I did non technically with a tape measure when I changed front struts last year. I don't have a lift but I did the process with floor jacks and it worked for me.

 

Back again.
Checked under car, it has height sensors on both front lower arms, so as mentoned it is an early car.
Lowered car on the hoist with back wheels just off the deck.
Ran engine and with ZF in drive ran at 40 to 50kmh for 5 minutes.
I was in the driver's seat so could not get out of car and hold 40kmh at same time to hear for compressor sound.
However, no sign of front risng at all.
Took very close look at dip at end of driveway. Not possible to get over it with front suspension so low.

I have the X350 pdf manuals, and this is from suspension section:
------------------------------------------------------------------
Static, parked with engine running Stance mode
· Lifting with reservoir
· Lowering permitted
· Compressor unpowered unless reservoir pressure is below a preset minimum and the
vehicle is below the compressor activation height.
------------------------------------------------------------------------
So the compressor should have run unless:
a) The reservoir was full and at max pressure. b) The compressor itself or system control failed.
Next step:
c) Maybe reservoir is full but sytem control is faulty and not raising front.
Seeing there are independent height sensors with individual solenoids for each wheel not likely both sides would fail at same time.
That points more to a control system fault.
d) Motorcarman suggested battery disconnect for hard reset. You never know, I will try that now.

e) I have not found any wiring or air system diagrams for the suspension in my pdf files.
Are they there somewhere ? Or is there a download ?

 

This is where you have to not overthink it. If the system was working when you started the transmission project then it seems hard to believe something went tragically wrong just sitting. The first place to start is to confirm that the compressor runs. The rest doesn't matter if you can't build air.

Running the car at speed off the ground has all of the height sensors hanging. The car is going to think the struts are full.

 

I claim this 25mph stuff is being misinterpreted.
It also says "in normal circumstances" and "below which residual pressure is utililized". It doesn't say about abnormal circumstances, or no residual pressure in the reservoir.

I am certain I have heard my compressor running, parked with engine running. I can only hear it with my old ear up close to the front bumper, and I didn't do that at 25mph...
(This is without any "vehicle too low" message, but with the reservoir depleted, due to very slow leakage)

 

Running on from jluvzcarz, what could have been disturbed by having it on a hoist? Like, broke a sensor or something.

 

Hi Richard,

Sorry to join your thread late. I haven't had time to ponder your situation, but my first guess is that you may have a combination of at least two issues. One is leaking front air springs. The other is that the Air Suspension Control Module (ASM or ASU) is in Jacking Mode. Here's what the Training Manual has to say about it:

Jacking Mode: The system recognizes customer vehicle jacking and vehicle ramp operation.The result of detecting either condition is to inhibit any corrective action from height changes where no response is detected. System inhibit is to prevent problems occurring with the vehicle lowering and a possibility of the jack or vehicle becoming stuck.The system monitors height changes at the corner being jacked up. If the system lowers the air suspension but no reduction in height is achieved, the system will time out at approximate 10 seconds.If all four height sensors change by preset values, the system will recognize the vehicle is being lifted on a hoist and initializes the inhibit function. Inhibit mode will continue to exist unless the vehicle height returns to normal or a wheel speed signal 2 m.p.h. (3 km/h) is detected. The above events are triggered by either the height sensor arm change in position or a wheel speed message on the CAN bus.

One would think that by running the car in Drive on the lift, the computer would think the vehicle had exceeded a road speed of 2 m.p.h., but perhaps the ASM needs to see all four wheels exceeding that speed and not just one or both rear wheels.

I think Bob's idea of a hard reset may be your best next steps under the circumstances, followed by letting all of the air out of the system and then seeing if it will reinflate on a restart.

There is a lot of confusion about system operation, even among members who have studied the Training Manual. The manual clearly states that with the engine started and the transmission in Park, the compressor may run for up to 120 seconds to repressurize the reservoir. After the 120-second cycle has ended, the compressor will not run again until the vehicle speed exceeds 25 mph, OR, the engine is shut off, the compressor is given at least 45 seconds to cool, then the engine is started again. But the compressor will not run at all if the ASM is in Jacking Mode.

A hard reset may work to clear the ASM from Jacking Mode. Disconnect the negative battery cable and touch it to the positive cable (which can remain connected to the battery) for 2 minutes or more to drain the keep-alive memory capacitors. It may help to have the key in position II (Ignition ON) when you perform the reset, but try it first with the key out of the ignition.

Cheers,

Don

 

Thanks for all the feedback.
The jacking mode is a new one on me, but makes sense.
There has been a slow leak somewhere for a while because it takes a few mintes to clear the "car low" message if the car is not driven for a week.
From member's comments that is most likely leaking struts, probably at the front too.
I do not think the slow leak has suddenly become catastrophic unless it bleeds all the air stored in the reservoir.

a) Tried a hard reset, but only had the battery off for 5 minutes. Will try 2nd time and discharge stay alive caps as suggested. Might work.
b) Over the years had this car up on hoist many times to change oil and do sundry fixes.
Usually not up for more than a few days, and never had the problem I now have.
Last few months car has been up for to 2 or 3 weeks at a time on 3 occasions without trouble.
Fouth time unlucky.

c) Removed compressor which had shown no sign of running on the car.
Noted there was release of air when removing outlet pipe, so if there is no "non-return" valve in reservoir I guess that is air from reservoir.
Must say it did not feel like 4.5L of 15psi air.
Connected 12V battery charger to compressor and it runs. Finger over outlet shows it pumps air, hard to tell if it is 15psi.
d) Compressor working ( well maybe not at 100% ) is a bummer. If not working would be 99% certain a new compressor would fix things.
I think I will order a rebuilt unit anyway, or perhaps just pull it apart and see if replacing the teflon seal looks a good bet.

e) Assuming compressor was good and reservoir full why 2 front struts low ?
Since an early car with separate height sensors and individual solenoids to adjust I suspect either a total solenoid block fail ( fuse ? ) or a fail in the ASM.
Could be:
Height sensor input to ASM is faulty.
Hardware or software glitch means ASM does not compute correct action to take with regards to inputs.
ASM output drive to compressor is faulty.
Compressor does run but system has a pressure control sensor that is faulty and inhibits compressor.

f) Anybody tried this ?
I could jury rig the compressor by connecting it to the oulet pipe and run the compressor on my battery charger for 120 secs.
If there is a pressure relief valve should be safe.
If a functioning ASM monitoring a pressure sensor is normally used to limit pressure that will not be safe.
Any comment ?

 

Pulled the compressor apart.
Bore looks good, no obvious problem even the teflon seal looks reasonable.
Bagpipingandy will get an order for a kit.
About 10 days from now should have the compressor back in action, then on to troubleshooting.
Small chance compressor was the issue, more likely a need to go further.
If hard reset produces no result it would be good to have a diagram of wiring and air system.

 

It seems to me (just guessing), that a worn-out compressor wears out the compressing parts; the compressor motor should still run when commanded.

Are you sure you want to pass onto your stepson? Fairly standard issue, but I have a policy of not passing on used cars, or houses, onto family because of implied warranty...Not Worth It !!!
(not that I've been caught out, but I ensure that I won't be-advice for sure but no deals to family for my own "crates")

 

[QUOTE=ChrisMills;2388899]It seems to me (just guessing), that a worn-out compressor wears out the compressing parts; the compressor motor should still run when commanded.

think so too, and it seems the compressor was not commanded to run.
Like I said, I will replace the seal but I doubt it will cure my problem.

 

JUMP THE RELAY and see if the compressor runs?