2005 XJ8L. The air suspension seems to have developed a mind of its own over the past few weeks. It started with the entire car lifting to maximum height and staying that way. That was a rough ride home.

I used SDD to deflate the entire suspension system out of concern that it would eventually damage the air bladders in the shocks. I can inflate and deflate both front and rear axles - the car visibly goes up and down. I've attempted to use SDD to recalibrate the suspension, but it seems to just stay in an "air suspension leveling in progress" loop, although I can see front and rear changing heights. I've also pulled the battery to clear the ASM memory - if that really works?

Sometimes the rear suspension raises all the way up while I'm driving - starts out normal but by the time I get to work it's up. Lately it's decided to be elevated on the right side, low on the driver's side.

Air Suspension Fault and Vehicle Too Low warning lights are on at the moment. Briefly after attempting to level the Low warning light went off, came back after a drive around the block.

I'm sure I've got a small leak somewhere - the car loses height overnight in cold weather. Until now it's always sorted itself out after warming up. This seems more like a computer issue than a leak, since the car will raise and lower by command from the SDD, and the rear raising itself to maximum doesn't make any sense as a response to a leak in the system either. Any thoughts?

 

Just putting some ideas to start with:
- first, the car starting to lift and staying there: maybe a height indication not recognised or taken into account (defective sensor) ?
- ups and downs: maybe a corrupted ASM indeed or a leak somewhere combined to an unrecognised height?
You seem not to have successfully completed a suspension recalibration. What SDD and interface (Mongoose or VCM) did you use?
Probably more skilled members will chime in.

 

I'm using MongoosePRO with SDD v130. No, I haven't been able to do a calibration. I just came in from trying. It started off by attempting to level - I didn't even get to put in the numbers. After I aborted the session, the left side went to normal height, and the right side is still jacked up.

 

Didi you do the calibration with an adequate stabilised power supply connected?
If not, try redoing it using a power supply.
If so, maybe your MongoosePro did not fully communicate with the ASM; there are issues sometimes when not using a VCM but you may know that already, see e.g post #16 in the following thread:https://www.jaguarforums.com/forum/x...aution-164675/
But that would be unlikely with a genuine MongoosePro though...

 

Just tried again with power supply attached, no difference. I can enter the calibration routine, it displays a 'leveling in process' message, and I can hear the compressor coming on and off (and now the rubber mount has broken so I can REALLY hear it come on), but the routine doesn't complete (I gave it over half an hour) and the "Abort" command does nothing.

Interestingly, when I force close the SDD, the left side rises to about normal height, but the right side remains at maximum height. Now it's not saying "too low", but the suspension fail warning is still there, with c2303 (think that's right).

 

If you know you have a small leak somewhere, I would certainly track that down first. With so many sensors on these cars, it is too easy for one problem to effect other areas and seem like you have other problems, when you may not.

As paydase said, it could be a ride height sensor that is out. Is that the only active code showing when you plug in your Mongoose? Are there any relative stored codes?

A year ago I had my XJ suspension go stiff with a fault message in the dash. I found that a mouse had chewed through the wire connector to the air shock. That one loose wire placed all four corners in the jacked up, rough riding setting. As I mentioned earlier, track down the and remedy the known faults first. It could be a computer gone bad somewhere, but that would be my last resort. Though it is possible, especially if you've had water damage inside or something similar in the past, a corrupt computer is rare on these cars.

 

Hi Aaron,

You've received some good thoughts and questions already. I'm looking forward to knowing all the DTCs that SDD finds, even those that seem unrelated to your suspension issue. For example, if you have multiple codes that suggest a problem with circuits that all pass through the same electrical connector, or problems on the same network as the ASM, that could give you a clue.

Here are some additional random thoughts:

One possibility that comes to mind is the ground point used by the ASM. The stud is below the rear seat on the right side, and it would be worth giving it a thorough cleaning with a small brass brush and zero-residue electrical contact cleaner. The stud, wire ring/eyelet terminals and nut are all made of aluminum, and are susceptible to the formation of a microscopically-thin layer of aluminum oxide (corrosion) that is an electrical insulator that interferes with proper current flow. While you have the lower rear seat out, it would also be worth removing the seat back and cleaning all four connectors at the ASM.

It would also be worth cleaning other electrical connectors in the system: those at the valve block in the trunk, and the ones at each height sensor. Also visually inspect each height sensor for any signs of physical damage.

Let us know about DTCs and we'll try to offer more ideas.

Cheers,

Don

 

I have seen others comment on the car jacking up. My car has a leaking strut. Think it is the drivers side rear. That corner is low after sitting for four to five days. The air compressor runs a lot the first 15 - 20 minutes of driving.
Drove home yesterday and see the XJR sitting level on my sloping driveway. The rear is six inches above the tires. The front is down. Looked again this morning still sitting level. Looks wicked with a dropped front and jacked up rear.

 

OK, I may be blind - I have the rear seat boittom out and see the ASM behind the seat back, but where is the grounding stud?

 

Well, this is what I've got. Still doesn't make sense for the right side to raise up and the left side not. I still haven't found the ground post to the ASU. SDD isn't letting me complete a leveling cycle.

Related DTC:
C2302 ASU Levelling plausibility error

Unrelated events:
C2780 ASU ECU in manufacturersub-state
B1671 ASU Battery module voltage out of range
C2302 ASU Levelling plausibility error
B1676 DDM Battery voltage out of range
P1000 ECM System check not completed since last memory clear
P1582 ECM Throttle monitor data available
B2414 FEM Headlamp washer relay circuit short circuit ground (not fitted?)
C1742 PAM Rear sounder circuit failure (yep, went out the other day)
B1221 REM Left seat heater output open load (because the seat is out)
B1222 REM right seat heater output open load

 

Not an expert but I see that you have voltage issues in the ASM and in the REM.
Is your battery in good order? (that could that affect the way the modules work)
The causes could be also bad groundings of the ASM and of the REM

 

Here's a snip of the ground location diagram from the Electrical Guide, which you can download here:

2005 XJ X350 Electrical Guide




For Jaguar's definitions and possible causes of each DTC, you can download the DTC Summaries Guide from this forum at this link:

2004 X350 DTC Summaries Guide

I wouldn't worry about the C2302 just yet - that's a common code when the piston ring in the compressor is worn and can't charge the system as quickly as the ASM expects. Easily rectified with bagpipingandy's new piston ring, and probably not the cause of your weird system behavior.

Just to pick a couple of relevant codes, the guide says that C2780 means the ASM requires configuration. That can be done with a dealer-level system like WDS or SDD, and you may very well need to follow through on that.

B1671 ASU (Air Suspension Unit = Air Suspension Control Module or ASM) Battery module voltage out of range: Possible causes given are "Charging system low/high voltage fault, Battery power supply circuit: high resistance (for example, corrosion on battery power connections and/or grounds).

Note that the Driver's Door Module (DDM) is also reporting battery voltage out of range (B1676). It might be worth checking the schematics to see if the ASM and DDM share the same power feed upstream.

I have to run but will continue to follow your progress.

Cheers,

Don

 

The battery isn't even two years old, but that could still be a problem. I kept it connected to the charger while doing the tests - I wonder if this is responsible for the "out of range" errors.

If anyone has a picture of the ASM ground post or a detailed description of its specific location in relation to the ASM, that would be great.

I agree that electrical connectivity could be the issue - that or possibly a bad ride height sensor.

To me the right side consistently going high and the left side low seems like a clue.

There was some dampness under the rear passenger side seat - not sure how water could get there???

C2780 ASM requires configuration - I'm having an issue with SDD not completing a calibration. It will stay half an hour or longer at "leveling in progress". Does this relate to C2780?

 

If you have moisture under the rear seat, a blocked or kinked sunroof drain is likely the culprit. Corroded connectors under the seat can cause a lack of communication with the ASM. As Don said, check and clean the grounding stud. Also check and clean the electrical connectors under there.

Here's a thread, check post #5. A member thought he needed to replace suspension components due to it riding uneven, when it was water from a blocked sunroof drain tube that caused corrosion to the electrical connectors under the rear seat.

https://www.jaguarforums.com/forum/x...nection-77665/

The sunroof has four drain tubes, one at each corner. Members have been successful at feeding nylon/plastic weed whacker string down the tubes to clear them out. Others have used compressed air, though I've heard you can blow the connectors apart if not careful. I would steer clear of metal wire, as you could cause damage.

Here's a helpful thread with pictures, courtesy of Magmedia. He shows plenty of pictures of the electrical connectors under the rear seat that can be cleaned.

https://www.jaguarforums.com/forum/x...-c1893-150514/

 

Thanks. I see that in that second thread he couldn't find a ground stud for the ASM either (post #6)! https://www.jaguarforums.com/forum/x...-c1893-150514/

 

Update:
At this point I no longer have the "air suspension fault", but I still have a "ride height too low" warning and red light. The right side is higher than the left, although the left side looks almost correct.

I cleaned the connectors under the rear passenger seat. One had some noticeable corrosion, the other looked fine. Other connectors in the area looked fine.

Using SDD to scan modules and setting the car to customer mode seems to clear the "air suspension fault" warning. I can drive it around and it doesn't come back.

If I attempt to do anything that initiates a leveling routine (ie. calibrating or geometry), the "air suspension fault" comes back. It won't complete the leveling, at least given 30 minutes. Attempting to abort doesn't seem to work, so I wind up back where I started, with ASF and ride height warning both on.

So, after scanning modules again and setting the car to customer mode, leaving me only the ride height warning, I've still got a lopsided car.

No related DTCs, Unrelated DTCs all 0%:
B1895 DDM Driver's/passenger's door ajar output - circuit failure (temp)
P1000
P1582 ECM Throttle monitor data available (perm)
B2414 FECM Headlamp washer relay short circuit ground (perm)
C1742 PAM Rear sounder circuit failure
U3FF6 REM No description available (perm)

 

I think I'm recalling that the first time I tried to perform a suspension calibration with SDD it hung up, so it may take multiple attempts to get it to complete. The fact that you can deflate the suspension with your SDD would seem to indicate that it's communicating properly with the ASM.

If you're using a reliable interface cable like a genuine Ford VCM or Drew Technologies Mongoose, one thought is that it might be worth reflashing the ASM before trying another suspension calibration. If you decide to try this, read up on all the warnings. You need a good high-current power supply for your battery (Jaguar specifies the Midtronics PS-550), and your laptop must be plugged into its power supply for the entire procedure. And be prepared to need a new ASM....

Cheers,

Don

 

When I put the car in "customer mode", the air suspension fault goes away. The compressor raises it so that the "low ride height" goes away. So, no error codes, but the ride height is still uneven. Right side is too high, left front about right, left rear too low.

I've tried re-flashing the ASM, but every time the car gets the signal from the software to run the self-levelling routine, it throws the Air Suspension Fault and stays in "levelling in progress" for as long as I'll let it run. This happens when attempting calibration as well. I have a battery maintainer on the car, and the laptop plugged in.

Also, I've noticed that while I don't get a fault when commanding the car to inflate or deflate the front and rear axles, it isn't inflating them to maximum capacity. If I say "inflate", should it raise the suspension all the way up?

I have followed the suggestion to manually deflate the suspension and touch the battery cables together to force the car to enter its own self leveling routine. No effect.

I am using a British Diagnostics Mongoose Pro with SDD v 130. I have been able to program other modules, but ASM seems to be a problem. Per this thread, https://www.jaguarforums.com/forum/x...ke-xjr-140197/, user @Naso--Literatus reports that SDD can have problems with flashing the ASM, and the solution was to use IDS to load "asbuilt" conditions to overwrite a corrupted VID block. So, I've contacted British Diagnostics to see about that. If you know how to do that with SDD, I'm all ears.

 

Mr lovt
This is a little routine which I have suggested in the past and it worked!

With the key out of the ign. find the compressor fuse and remove it.

Depressurise system completely by cracking open a joint eg on the ballast tank.

When system depressed replace compressor fuse.

Start engine and if necessary drive it around for up to 20 mins.

 

Thanks, Merion1. I did exactly that procedure this evening, but the ride height remains uneven. I did the equivalent earlier by disconnecting the battery and cracking open the air system, but it was worth trying again.

At this point, these issues are outstanding:
1. The ride height remains uneven - right consistently higher than the left by about 1.5 inches.
2. Left rear raises and lowers at idle. (I replaced this one with an Arnott last year, so I'm skeptical that it's leaking. Once I get the proper fittings, I'll be testing this shock for leaks.)
3. Cannot complete a leveling routine with SDD. It hangs at any self leveling. Waiting to hear back from British Diagnostics about using/getting IDS to re-flash the air suspension module.
4. Moisture got into the cabin, but I have not been able to replicate this. The sunroof appears to drain correctly. Possible extremely heavy rain was more than the drainage could handle? Possible a clog cleared under pressure? I'm still investigating, as this appears to be the source of the problems.
5. Ground post for air suspension module - I believe G17 has been identified as under the trim at the RH rear foot well. There is a bolt there, but not a stud as with other grounding locations. Nothing is tied to this, it just holds down a wiring harness. I don't see the ASM actually grounded to anything, other than being riveted to the trunk wall.

And these issues were resolved by cleaning the connector in the passenger rear footwell and resetting the system:
1. Air Suspension Fault cleared by putting the car in "customer mode".
2. Ride height warning cleared by putting the car in "customer mode" and giving it enough time to raise the car to an appropriate height.

Thank you to everyone - all your suggestions are welcome.