Morning Gentlemen.

I have a very good friend with a 2010 UK spec X351 3.0 diesel. He was driving as usual the other day when he heard what he described as a thumb accompanied by a weird smell. Hey presto the rear is dragging on the ground.
There are NO fault codes using an AUTEL MaxiSys scan tool. I went through a number of tests that led me absolutely nowhere. I can say that the front is - as you all know - separate in all but the ride height sensors. The front is inflated as it should be. Front sensor rear correct ride height and respond to bouncing. The rear sensors read -91mm and -86mm but also respond to bouncing. The compressor works and does pressurize the tank. Tank pressure reaches 16bar. All the while the valve body sits there humming and gently squeaking. Even with commands send to raise a corner, nothing happens. If I put the suspension into build mode, the dash responds with "Not in Consumer Mode". Of course nothing happens. Take the car out of build mode and the consumer warning goes away and still nothing happens. Running height calibration tests will start the compressor and it will run until pressure reaches threshold but the suspension does not move. With the pipes removed from the valve body I can raise and lower the car myself using an air compressor. I capped off both sides and this morning the car is still raised so I know there is nothing wrong with the air bags on the rear struts. I am currently airing - no pun intended - on believing the valve body is the failure. I removed it and gave a couple of whack with the rubber mallet and well as blowing compressed air into it. All valves are shut so no air gets blown in. I have yet to find anything that smells in the boot (trunk) I rang Jaguar who told me the car MUST not be driven ever with no air in the bags.

Anyone got any ideas. really want to solve this. Thank you

 

The X351 only has air springs on the rear wheels, the fronts are coil springs. The previous model (X350/X358) had air springs all round. If the compressor runs and charges the reservoir, and the height sensors transmit level data, then the problem must lie in the valve block and/or the Air Suspension Module.

Are there any warnings on the dash display. On the old model, one would get "Air suspension fault", or "Vehicle too low". If you're getting nothing it implies the ASM thinks all is well. However this assumes your code reader can read all the Jaguar codes.

 

Thank you Fraser. Understood. So there are ride height sensors at the front but no air. Only had rear wheels off looking for damage when first I got the car. So the height of the fronts are used to calculate the target height of the rear. It would appear from the schematic that the valve block is not on the CAN BUS itself so there is likely a PWM signal from the ASM to the VB. I am going to back probe the data line on the VB and see if it is being spoke to. However I wonder as I only see one data line if the VB is dumb in as much as it doesn’t confirm commands back to the ASM. I am concluding the pressure sensors on top of the struts are the only feedback the ASM gets as it whether or not air is under pressure. So the ASM could be commanding a pressure increase to a faulty valve block and not seeing a change at the strut, then stopping. No commands from the 40 or so diagnostic options my Autel offers make any difference to the compressor. If I say open reservoir valve I do so the pressure drop in the tank. But if I say open RR valve nothing happens.

No air in the system at all currently as I was pressure testing the vessel and compressor yesterday. They are both fine. However when the engine is started, the ASM should see the rear is on the floor and immediately start the compressor to charge the vessel, then close the reservoir valve and open both strut valves. None of this happens. The lack of fault codes is annoying.

Thank you for assisting.

 

Edit: Yes there is a warning on the dash, sometimes. It is a RED triangle and the message "Air Suspension"

 

Greetings.

An update. With an oscilloscope on the data pin of the valve body, only commands that show up are "exhaust tank valve". I definitely have the required power and ground on the ASM. I have the 5v reference on the valve body from the ASM and I see 12v on the valve body feed. With both wheels off and both ride height sensor free, I can "see" their supply voltage change on their sense O/Ps. However with both reattached and the car back on terrafirma, I get -73mm on the right and +91mm on the left, when looking at live again again. Am beginning to think I have a partially open carbon track on the LHR ride height sensor. If I run the compressor relay manually the pump runs and I see gallery pressure rising. The fault service manual suggests one cause can be, but does not indicate it to be ***, is the front right wheel ride height sensor. ***Both front ride height sensors report voltages within a 10th of each other and heights within 3mm so I shall discount that for now.

Running a purge test to exhaust all air works as I pressurised one bag with my airline and quickly plumbed it back in. However when the refill command is sent from the test module the compressor only runs for two seconds at a time repeatedly, which suggests to me it is hitting a deadend pressure wise. I am airing, again no pun intended, on the valve body being the issue but I am not being presented with definitive data and only have the "gut feelings and experience" on 88 - 01 BMW.

Help me Obi Wan......................

 

Is anyone familiar with the logic used by the Continental ASM in the X351?

Thanks

 

Update 13/10 @ 1234 GMT

I am almost certain the issue is the NSR ride height sensor. The left was moving, I am certain, as in the diagnostics showed it changing value. However it was miles away from what the OSR was showing. It doesn't do anything now. This led me a merry dance of course. I have done end to end continuity tests on the loom and am 100% satisfied it is fine and yes I shock it bent it twisted it etc. With the car jacked up, I can move the RH sensor from say -73mm to +50mm but the LH moves without affect. So based on the inhibit rules of the ASM this is enough to knock the system offline. New sensors coming. Always best to change in pairs so that is what I have ordered. I will post back in 5 days when they arrive as Jag doesn't have any locally.

 

An update for those interested.

Turns out the N/S/R RHS was intermittent! If we assume in this example that its usable range is 0° - 90° it worked between 20° and 40° but not between 0° and 19° or 41° and 90°. Highly unusual for a hall effect device but there is quite a bit going on inside. I opened one up. Anyway as they are cheap, I replaced both and took the car out of build mode and the compressor started for about 5 seconds. The ASM could obviously see the RHS were "in range" so the compressor ran for 5 seconds, paused then ran up to full pressure. Whilst this was happening I could see data going to the valve body and noticed that the car was rising. It got to a ride height deemed as normal. I ran the calibration sequence and now the entire car is within +/- 2mm on flat ground.

Dead easy to get off if you simply set fire to the RHS as I did, as there was no way the - rusted to f... - T25's were coming off conventionally. Replaced them with 4mm A4 stainless and grease (NOT copper grease!)

Part Number is C2D16582. Total replacement time including raising and lowering the car was about an hour. Calibration about 10 minutes.

 

Great troubleshooting and thanks much for filling us in on the repair!
The good thing is we don't see much if any air suspension problems on the X351 after jaguar dropped the front air bags and just kept the rear set.
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Hi every one
I have a 2011 xj
and while driving tester day the rear suspension stopped working and not it’s dragging it’s **** on the rear
After a while I had a “dynamic suspension fault” show up on the dash

as I understand it these are the main areas to look at
compresser (can’t here it running from underneath)
dynamic suspension sensor (not sure where it is)
ride height sensor “rear left side)
rear struts (can here air escaping but then I can hear the compressor running so may not be them.

anyone give me any advise as where to start?
I have a cheap obd code scanner ordered but not here yet

thanks in advance

rob

 

jasperpilchards, welcome to the Forums. Lots of good information here. But, we do ask one thing from you. Please stop by the New Member section and tell us a litlte bit about yourself and your car and why you got into jaguar. This will give you a chance to meet those that make this place what it is. We believe in being more of a family here and are willing ot help each other out as much as possible. This is not something that you find in a lot of car groups. We pride ourselves in being that little bit better.

As for your problem, it can be a number of things causing the error that you are seeing. For that code to show up, it could be a problem in the steering, with the body yaw sensors, the shocks, etc. There is like 30 parts to the dynamic suspension setup. The dynamic suspension system doesn't really look at the compressor and the ride height of the car. It is more interested in how the car is leaning side to side for what the steering input is, how fast he car is going, amount of braking, and what sort of road surface that it thinks you have (as taken from the 4 ride height sensors, measuring how bumpy the surface is). The system then is adjusting how stiff the shock needs to be to match the conditions to firmness to give maximum driving experience. When you get the fault, you should notice that the car gets really stiff and bumpy. This is because the system defaults to maximum stiffness in the shocks leading to the rougher ride.

I have had this issue and in my research, I found one other person to have had the same issue. I think it more by chance than anything, we both had the same fault. The right front shock was bad. If you get a higher end code reader, you need to get into the C-codes of the car and that should tell you which component in the system the vehicle is seeing as the problem.

I am a little confused to hear you say that you can hear air escaping, but the rear end is not dragging. If you park your car for say an hour and then come back out to it, is the back end of the car sitting low? If so, then I would be looking at your rear air bags as you may have popped a hole in one of them and this is causing what you are seeing. If the rear remains at a proper height, then the air bags are good and would go back to finding which C-code you have that is related to the dynamic suspension system.

 

If working on the air suspension you will need a code reader that will read very deep into the Jaguar only codes.
What codes does your car currently have? If none then I don't think you have a scanner that can read what you need. There are dozens of codes associated with the rear air suspension and we must start with those.

Are you familiar with SDD? It's the factory diagnostic software and sometimes that is needed to unravel your cars problems.
Also do you have a service manual for your car? They are huge so I can't post it to the forum.
I think that is also mandatory for your problem plus it will be useful for other stuff too.
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