C2302 - Fault - ongoing investigation

[njepson394]

Hi All,

I've an intermittent Air suspension fault currently on my 2003 XJR, similar to KBS's thread:

viewtopic.php?f=290&t=14109

So far I have had the system fully mechanically checked out (at the annual service). No leaks, no compressor or airbag faults, and ride height checked out.

Using a scan tool i was able to identify a C2302 level plausibility error. I cleared the code, but it returns. The fault shows the amber light and air suspension fault warning. In addition the suspension feels firmer and less compliant, I'm assuming that this is because the ASM is no longer actively controlling the ride height, and adopts a default or "safe" mode?

A stop and restart always clears the dash fault.

This week I had the car up on the two post lift at work. I checked the wiring and connection to the 4 ride height sensors on the suspension arms. No evidence of any damage. I took the 2 rear sensors out to examine them they seem fine, though offside had more play in the sensor, put some connector cleaner on and refitted. The suspension dropped to minimum height. I started up and the ride height quickly returned to normal and stayed there. No re-occurrence of the fault on the return home.

Unfortunately the problem has returned and is now occurring on every journey.

My feeling, based on the fact the ride height is always normal, is that it's likely one of the ride height or accelerometer sensors giving an implausible signal to the ASM, or the ASM itself.

• Is there a way to narrow down the fault to a particular sensor? - Does this require a full Jag spec diagnostic tool, or are there afternarket scan tools that would give that level of information? (I used an ICarsoft i930 to diagnose the C2302 fault).
  
  Could it be damaging to the system to drive the car when the fault is on? does it put extra stress on the compressor or airbags in that mode?
  
  Does anyone have any recommendations about where to get replacement sensors?
  
  Is it worth disconnecting the battery or removing the ASM to give it a full reset?
  
  I'm concerned about taking it to an independent specialist (I've not built up a relationship yet with any in my area), as the starting point is usually the compressor (which is expensive) and I beleive to be in good working order. Does anyone have any advice on this?

Thanks guys

[davidr]

As you say, the starting point here is usually the compressor. Whilst it may be working it may be less effective due to the common issue of piston ring wear. This makes it take longer than the optimum (I think 40 seconds?) to achieve the required pressure. The computer interprets this as a leak and hence the plausibility error.
New pumps are expensive but there is a kit for changing the piston ring that only costs around £25.
If you don't mind getting a spanner out then this has got to be worth a try. It's not very difficult if you're careful. There are threads on here with more details and there was an article in the Club magazine a while ago where Mike Kennedy refurbished his.

[njepson394]

Thanks for your reply davidr,

You are absolutely right that's where I'd start, normally, however..

Here's why I don't beleive it's compressor related:

• When I'd had the car up on the lift last week it only took a very short time to return to normal ride height 20-30 seconds.
  
  1month previously the garage which did my annual service gave the whole system a thorough check including the compressor operation.
  
  The ride height is always normal
  
  There has not been a low system pressure or leak fault
  
  Error usually occurs between 5-30mins into a journey suggesting an intermittent fault

Can anyone suggest some next steps in identifying possible sensor issues?

Is there a way to check the ride height sensor operation, such as with a multimeter?

Is there a good specialist in the Midlands area who could help identify the issue?

[njepson394]

Update -

Using the record feature of the Icarsoft scan tool i've been able to get some more information on the error:

See attached 2 photos -

The data suggests that there is a rear left damper firmness Error.

For the logs leading up to the C2302 plausibility error the Rear left damper solenoid valve output control is open (all others are closed).

The ride heights of all 4 dampers at the point the error occured was normal.

I will repeat the recording tonight to ensure the same mechanism triggers the fault.

Does anyone have any suggestions as to what this could be or how to fix it?

[PaulGover]

If one valve is open, and it says there's a) implausible levelling and b) damper firmness error, it appears that either the control is desperately trying to raise the rear left damper, without result.

I'd suspect either a failed ride height sensor giving incorrect readings, so the control box thinks the suspension isn't moving even when it is, or possibly the damper firmness error means the damper is seized or the air pipe is blocked/flattened/leaking, which of course would also mean the suspension doesn't level when it should.

[njepson394]

Hi Paul,

I'll have a look at the hose to the left rear damper tonight.

It could be the sensor. They look quite easy to change over, however do they require re-calibrating once installed? Does this need to be done by a Jag specialist?

[njepson394]

This afternoon I got the car up on the ramps, for a seperate issue.

I also took the time to inspect the air pipe to the rear left damper, nothing to suggest it's not working normally. - Thanks Paul

Once dropped the car returned to its normal ride height very quickly as is should.

The fault again re-occured on the return journey, again with a c2032 and damper firm error.

in addition the rear left ride height appeared slightly low once I returned home (after fault had occurred) this was backed up by the data log from the rear ride height sensor. It also felt overly firm on left right.

I feel now that it is likely it is a rear left air spring which needs replacing.


Please if anyone thinks it could be something else, let me know.

I'm in a quandry:

• Do I ask a garage to replace
  
  Do I swap it myself

What's the feeling amongst members?

How much is it likely to cost either way? should I go with OEM or aftermaket? (I'm looking to keep the air suspension system not to swap to coils)

Any other advice out there for replacing left rear damper? Are there any special tools required (press, ball joint splitter etc...)

Will I need to have it calibrated once it's fitted?

Any garages in the midlands people would recommend for suspension issues? Any friendly to the JEC?

Thanks for your help and advice.

[J44EAG]

Jaguar OE is Bilstein in a Jag box. You can buy from Bilstein direct. That could save money.

Initially, I`d also contact Eurojag who are likely to be able to supply a good warranted replacement for very reasonable money.This could well provide an economical fix for a fraction of the as new prices.

You could contact Vince at Air Dominance at Cheam in Surrey. AD offer a reasonably priced reconditioning service. I`d advise reworking both rear dampers to the same spec to keep wear rates across the car uniform. Google their web site for more details.

If you go to the suspension section of the X350 section, you will find my write up and appraisal of the various options. AD figures in the thread.

Mike K

[njepson394]

Hi Mike,

Thanks for the info. I'm having a look now at the options.

Keen to keep it as OE as possible so I'm thinking Bilstein. Their website only suggests one part number for all X350 variants. Is that your understanding.

Are there any mechanical differences in the Jaguar Green dot (comfort) and red dot (sport) springs?

Aerosus and AD are attractive options, for the cost though.

[J44EAG]

Green and Red dot specs seem to confuse suppliers. It is something of a dark secret. Obviously you will want the correct spec for your VIN. I would seem prudent to speak direct with any new or used part supplier BEFORE buying any replacement part. The mechanical differences are held within the damper unit but I believe the firmer Red sport units have smaller air bags fitted.

Steve Howard replaced all his air spring units with a conventional American coil over Arnott damper kit. A bridge out unit was fitted to cut out the air suspension control ECU. I believe the kit was well over £1200....about the same as one new Bilstein air spring! Steve wrote an article about the kit installation in one of our X350 magazine pages within the last 18mths or so. Worth having a look for that edition in the past magazine section on this site.

Hope that helps.

Mike

[PaulGover]

Another possibility occurred to me is that it might be a failing air valve. That would explain why the electronics was holding the valve open but no movement was happening, which of course would give a plausibility error.

[njepson394]

Hi Paul,

I've ordered an OE Air spring from british parts. £666.32 delivered.

The valve did occur to me too, However there was a loud (air) leaking noise when I jacked the left side up, convinced me sufficiently to get my wallet out.

I'm hoping to fit it as soon as I receive it. I will keep you updated on progress.

[J44EAG]

Ah! Sorry, I forgot that "test".

With the car on the ground on all four wheels, if you turn with your back to the car and grab and lift each wheel arch in turn, any leak from an offending air spring can be found as a hissing of escaping air! I understand that in such cases, the internal damper air bag is the culprit.

Sorry I`d not mentioned that previously. Matter locked in the back recesses of the brain!

Mike K

[njepson394]

Mike,

I think I'd read that nugget of information on one of the previous posts, hence the spending spree.

Cheers

Nick

[njepson394]

I believe problem is now resolved.

Replaced the old unit with a Bilstein damper.

Quite straightforward, to swap over, The most difficult bit was navigating the strut out of the wheel arch. I managed to swap them by taking the wheel arch lining out rather than the tie bar, as per the video below.

The bilstein video is a useful reference on how to change it. here: https://www.youtube.com/watch?v=u_p6ciSeTbM

Test drove earlier and no re-occurrence of the fault. I will drive it to work a couple of times (extended motorway driving) this week to confirm for sure.

The left rear ride height is as it should be.

Interestingly both British Parts.co.uk and Bilstein said that the comfort rear struts are for both sport and standard, it's only the ride heights that are different. That could be simply due to a lack of the sports dampers??

Either way the car feels much better with the new strut. I'm not sure i'll be doing the sort of driving that would be able to discern between sport and comfort.

I also wanted to sing the praises of British parts.co.uk as, although there was some delay's in getting me this part, Jack and Vicky (who I am now on first name terms with) were really pro-active in ensuring I got the part by today. They had an international courier collect it straight from Germany for me.

They were also significantly cheaper than either SNG Barrett or Bilstein themselves.

Thanks to everyone for their input and advice.