Fault code C2302 - Levelling plausibility error

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iRS
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Fault code C2302 - Levelling plausibility error

Postby iRS » Thu Feb 15, 2018 11:48 am

My car has turned into a dragster. The front ride height has dropped and the rear has stayed normal. Its reporting error code C2302 - Levelling plausibility error - Its not wrong there, but I'm perplexed why. Also, its not reporting a ride height error, air pressure error or any other error as far as I can see. Can anyone suggest where to start looking?
Last edited by iRS on Thu Feb 15, 2018 5:00 pm, edited 1 time in total.
Roger S
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Re: Fault code C2302

Postby J44EAG » Thu Feb 15, 2018 1:41 pm

I had this code after I rebuilt the compressor, Roger.

I couldn`t clear it with the diagnostic tool. I got on the internet and found that one guy had locked his car and walked away for just over twelve hours. Returning, he started the car, it rose back to height and back up the car came. I copied that and it worked for me also. Might be worth a try.

I also had a low rider when the N/S suspension sensor got knocked off when the car had a ride on a tow truck. Documented in my "What goes down must come back up"article in the magazine. Cable tied it back on as the clip was broken and all has been well since then.

Best I can do, I`m afraid, Roger.

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Re: Fault code C2302

Postby iRS » Thu Feb 15, 2018 3:40 pm

Mike
Thanks for the quick response. This happened yesterday and I was hoping for the overnight fix, but I drove it around the block this morning and it still low at the front. I drove the car into Aberdeen yesterday in snowy and icy conditions, it reported an CCS fault on the way in (I think that was snow on the cruise control distance sensor and have seen it before), then on a short journey within Aberdeen the CCS fault had fixed itself, but the phone went completely faulty and gave me messages that I had never seen before and then on the journey home the phone problem had fixed itself, but the suspension problem made itself known. So I was rather hoping that would fix itself too, but not yet.........Its good to have a car that fixes itself at least some of the time! This time I might need to get under it and pressure check the airlines.
Cheers
Roger
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Re: Fault code C2302 - Levelling plausibility error

Postby iRS » Sat Feb 17, 2018 8:15 pm

Here what the car looks like at the moment:
IMG_20180215_100508.jpg
and here's the code:
IMG_20180215_100306.jpg
so far, I have checked that the front's level sensor is intact - it is; and disconnected the battery for half an hour. I've also loosened off one of the air connections in the boot. No pressure. So my line of thought now is that the air pump is not generating pressure for some reason.
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Re: Fault code C2302 - Levelling plausibility error

Postby davidr » Sat Feb 17, 2018 8:31 pm

Roger - I've seen something similar before where one of the air lines was split.
The plausibility error usually comes up because the pressure doesn't come up quick enough which the system interprets as a leak. The normal actual cause of that is the compressor piston ring has worn. Mike has comprehensively written that up both on here and in the magazine.
It could be, of course, that you actually do have an implausibility error and your air system is compromised somewhere?
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Re: Fault code C2302 - Levelling plausibility error

Postby J44EAG » Sat Feb 17, 2018 9:34 pm

It does indeed have the droops, Roger! This can happen if `Orrible Rob drives your car. Then he tries to buy it from you, cheap!!

Mine would sometimes do a half droop overnight before I overhauled the compressor. Re-ringed, then no further issues in that respect.

Then the N/S sensor got knocked off the drop arm when loaded onto a tow truck. That`s when we discovered that issue. Tied the sensor back on to the arm and up came the suspension again!

The near side sensor on cars of the period controls the suspension height at the near side and the off side. On earlier cars, the two front sensors controlled both front air spring units. Thereafter, Jaguar used just the near side sensor but left the off side sensor in place presumably because it was quicker and cheaper to do so rather than rework the suspension ecu....As a result, the off side unit is pretty much a dummy.

Roger, I wonder if you have tried this idea. If you start the car and run the compressor to level the car, if you go to each air spring, stand with your back to the car at each wheel arch putting your hands under each wheel arch, try lifting each corner of the car in turn. If on doing so, you hear air escaping from any one of the four dampers, the leaking air implies a shot air bag in the air spring unit. That isn`t repairable as a DIY jobbie.

A heads up on air spring units. I`ve heard that Jaguar no longer have these in stock. Quite incredible. As a result even Eurojag are having difficulty sourcing enough second hand units. The answer may be is to contact Vince at Air Dominance in Cheam, Surrey. He can rebuild any clapped out units. See my suspension article in the magazine within about the last eighteen months.

Good advice from our David above.

Sorry. I`ve run out of ideas again.

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Re: Fault code C2302 - Levelling plausibility error

Postby iRS » Sun Feb 18, 2018 10:26 am

Dave/Mike,
Thanks both for your input. I'll let you know what I find. I've seen something on another forum about checking a relay and associated fuse, so that's what I'll do next. I'll then get the car in the air and have a look at the airlines. And may be bumper off, yet again........
Thanks for now,
Roger
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Re: Fault code C2302 - Levelling plausibility error

Postby iRS » Wed Feb 28, 2018 11:17 am

I'm still struggling to fix this problem two weeks on. However, I do believe I have found the source of the problem, but now have another to contend with. I have also learned a few things along the way, so will list them here for future reference.

On going back and checking over everything, I found that the front sensor was seized. It appeared mechanically intact and was reading something according to the icarsoft, but suspension movement was flexing the brackets and the sensor not actually moving. I ordered a replacement from Eurojag that unfortunately took from the Wednesday until the Monday to arrive. On the upside, they sent it complete with both brackets, linkage etc, so I was able to replace the strained clip that goes around the wishbone.The suspension now needs the height calibrating to account for a different sensor.

As luck would have it (there's no Indie within 100 miles of me) a local JEC member actually has the full Jaguar IDS. We attempted to calibrate the suspension height, but the routine was timing out. We think it may be because the pressure in the system is not high enough. The air compressor was replaced with a new one last spring and we can hear it cutting in, but cutting out shortly afterwards with the pressure at around 8 bar. The car is still sitting low at the moment. I have driven it about half a mile to see if that would do anything.

So the question is, does anyone know how much pressure it takes to raise the car? If its greater than 8 bar, then our diagnosis may be correct.

I have found out the following, mostly from the manual.

- System pressure 15bar (217psi) - not sure if this is working pressure or max design pressure
- Reservoir capacity 4.5 litres.
- The pipes are colour coded: blue, white, yellow, red, brown and pink. The 2 x 6mm pipes go to the front and the 4mm ones got to the pump, tank and the rears.
- The pump is controlled by relay R1 (right hand relay in the fuse box in the engine bay)
- Fuse 6 (40 amp) feeds the pump - also in the engine bay fuse box

Blue - Left rear
Brown - Left front
Red - Right rear
Yellow - Right front
pink - reservoir
white - compressor

The only air connectors that have been backed off were the one to the reservoir and at the pump. I can't hear any leaking air and the compressor isn't running for long durations trying to pressurise the system. It would be handy to know the normal pressure in the system.

Is there anything I'm missing here and does anyone have any further ideas?
Last edited by iRS on Thu Mar 22, 2018 4:53 pm, edited 3 times in total.
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Re: Fault code C2302 - Levelling plausibility error

Postby irishjag » Wed Feb 28, 2018 5:21 pm

Roger
I have a Jaguar training manual for the air suspension system that states normal running pressure is 7-9bar.
There's lots of other stuff in there that might be useful in solving your problem.
Send me an e-mail and I'll send you a copy of it if would help.
All the best
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Re: Fault code C2302 - Levelling plausibility error

Postby iRS » Mon Mar 12, 2018 9:58 am

I've finally fixed this problem - thankfully! Its been nearly 4 weeks since the problem first occurred.

I had a good long think about what the problem actually was and what I had done. I concluded that the problem wasn't necessarily in the calibration routine, but that the car would not rise or drop. Also, I decided to go back and check everything that I had initially checked, in case I had caused the secondary problem. It turned out to be so. When reattaching the air compressor, I had inadvertently trapped the rubber pipe that exhausts and takes in air from the bumper void. This would seem that it wasn't allowing the system to vent and that must have been stopping the fall and rise routine. To further confuse things, the system was actually showing pressure. I decided to swap the air compressor out with one that I rebuilt last summer with Bagpiping Andy's piston, cylinder and drying material. It will be interesting to see how this one gets on. I now have a nearly new compressor sitting spare, but at leastI have a working car again at long last.

For now, I have calibrated the suspension height to factory spec, but I might recalibrate it and set it just a bit lower.
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Re: Fault code C2302 - Levelling plausibility error

Postby davidr » Mon Mar 12, 2018 2:31 pm

Well done Roger! Isn't it a great feeling when you've been scratching your head for a while and then it rises majestically from the ground?!!
I had the same thing with my wife's Discovery whose back end was scraping along the ground (the car - not the wife!). I'd replaced a broken height sensor and it just wouldn't pump up again. When I thought about it I realised I'd not put the height sensor back on properly and, in effect, it was upside down! Fixed that in 2 minutes and then up she came!
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Re: Fault code C2302 - Levelling plausibility error

Postby J44EAG » Tue Mar 13, 2018 9:00 am

Sometimes the learning curve can be a bit steep. We live and learn.

For Rogers interest, my car was electronically lowered by 15mm all round. In actual fact, another 5mm at the back would not come amiss. Lowering slightly stops some of the body roll. Roger, you in fact drove my car in the 15mm lowered state when we hooked up at Fareham last year.

As regards sensors, you might remember my short magazine piece, "What goes down, must come back up" when I described how a sensor got knocked off the near side drop arm when my car had a ride on a tow truck. These things happen from time to time.

Well done, Pal.

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Re: Fault code C2302 - Levelling plausibility error

Postby jagmar » Wed Dec 05, 2018 2:39 am

Roger
I have a Jaguar training manual for the air suspension system that states normal running pressure is 7-9bar.
There's lots of other stuff in there that might be useful in solving your problem.
Send me an e-mail and I'll send you a copy of it if would help.
Hi irishjag, habing issues with my air suspension. Could i ask you for a copy of the manual you mentioned?

Tx

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Re: Fault code C2302 - Levelling plausibility error

Postby J44EAG » Wed Dec 05, 2018 8:48 am

This might interest everyone.

After I rebuilt the compressor, I drove the car for a couple of miles. The suspension suddenly stiffened and on came the MIL and an error message. As I only had the blue-tooth and Android diagnostic combo with me, I let it loose on the problem. I recall that plausibility code. It wouldn`t clear. I drove the car home and turning into the boat yard, there was a loud "pop" from the near side front of the car, exactly where the air compressor is located. The sound was as if I had driven over a full coke can. The code would still not clear so I disconnected the battery for half an hour. Still no joy. In exasperation, I locked the car up and shoved off to the pub to discuss the issue with my very experienced ex-motor mechanic friend. The car stayed un-moved and un-loved over-night without being un-locked. Next day, I un-locked, started up, the MIL was out and the message centre, clear. The car drove normally and the Torque app on the Android could no longer see the code. Seemingly, job fixed and no re-occurrence of the issue.

Sometimes there would appear to be no rhyme or reason for some of these issues and they end up being classified as a glitch and remain un-solved and something of a mystery. Nothing like electronics and low voltage systems to baffle and befuddle brains.

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Re: Fault code C2302 - Levelling plausibility error

Postby iRS » Thu Dec 06, 2018 1:53 pm

jagmar, I can send you the instructions that Irishjag sent me. Just let me know how to get them to you - email address etc.?
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