A few weeks ago I threw an air suspension fault. After resetting the faults in the computer, it has been off until now. I am getting an intermittent air suspension fault that code suggests the problem may be with the Relay. I have the owner's manual, as well as the service manual, but cannot find in either the location of the relay. I also did not see it in any other posts. Does anybody know which relay (I assume on the rear fuse panel) is for the air suspension?

 

Can you tell us what codes you get, please. The air compressor can start to fail and if it doesn't pump up the reservoir in a time defined in the suspension software, it will throw a code.

 

Yes, codes please. I have also experienced a suspension fault that was random and would come and go. After getting the codes read, it turned out that it was the right front shock. A few other members have had this same exact issue. When the fault was present, the car rode like a brick (went into dynamic mode).

 

Don't forget that the X351 only has air springs on the rear wheels.

 

Fraser, true. For some reason I had suspension fault on the brain, not air suspension. My bad.

 

Hello,

The fault code was "C1 A27-12 Compressor circuit". I could not find for Jaguar, but found this for Range Rover:, and my hand held computer (Foxwell with Jaguar software) showed the same thing. The code is:

C1A27-12 Compressor
Circuit

Compressor voltage
present when compressor
not requested

Air compressor harness
wiring short circuit to
power

Air compressor relay fault

Air suspension control
module failure

FWIW worth, the last time it did this there was 12v at the compressor, even when the vehicle was not running. The wiring diagram shows that it should not have voltage unless the relay is closed (or stuck, I suppose). As a relay is a simple electromechanical device, I thought I would start with testing it. The manual lists the NUMBER for the relay, but I do not see that the box is numbered or that there is a correlating diagram. Thanks for the help, all.

Enosgl

 

It seems a bit confusing but I only see a "Air Suspension Relay" and no "Compressor Relay"? But this relay does supply 12 VDC to the comprressor.




It is located in the rear junction box which is in the trunk.
Here is a listing of the fuse box - Can't find a picture of the layout but at least it does have numbers!




So it could be the problem and would be easy to swap with another relay for testing.
Since the compressor only has a couple of wires you could check that too.
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Thanks. Funny, as much as is documented there is no diagram saying which of the five relays in that box is "R10", as the wiring diagram and manual both say.

 

I guess the relay is F38 in the fuse box?
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Thanks. The relay is actually "R10" in the fuse box, and they ARE labeled if you get close enough. I pulled the relay and dissected and it is DEFINITELY well used, may have stuck at some point. After dressing the points, it seems to work correctly. Unfortunately, in addition to the aforementioned C1-A27-12/ code, there is a C1-36-01/ error. That correlates to an exhaust valve error. When looking at the plugs, I noticed the compressor was ambient temperature (65 degrees, but the exhaust valve very hot (180 degrees). Though compressors in this group do not seem commonly discussed, what might these symptoms point to?

Thanks for the help.

 

It's just so rare that I have never heard of a compressor problem on this model XJ? But it does point to a compressor problem.
I wonder if the compressor is the same as the previous XJ? If it is there is a TON of info about that one! I have rebuilt one using bagpipingandys great re-ring kit.
Might even contact him? He does all sorts of air compressor/air suspension repair kits now.

Air Suspension Repairs
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I rebuilt the Wabco compressor in my 2004 XJR with the same kit. The cars now use an AMK branded compressor. I found few cases involving compressor or exhaust valve (integrated with the compressor) failure, as well. Today the fault is gone, and the exhaust valve is not hot. The question is WHY.

 

Good news. I discussed with Arnott, and they agreed it was likely a compressor failure. The compressor not running when there was 12v at the plug (relay closed) confirmed it, as did the wiring diagram. About an hour job to replace (it took longer to empty the trunk, lol), clear the codes, and they have yet to return. If you run into the same thing:

1)-Arnott compressors are $400 or so, vs oem at $1,800. Added bonus is that Arnott's have a LIFETIME warranty, and good support for DIYers.

2)-Not sure on valving at the reservoir, so before disconnecting the hoses, I used my Foxwell scanner to release it's pressure. The service menu under suspension allows you to release the reservoir pressure, suspension pressure, or both. I did NOT release suspension pressure, so did not need to jack the car.

3)-The valve block is plastic and easy to cross or strip the threads. Be careful. My threads are questionable enough that I will replace it with an aftermarket piece just to be sure I do not have to touch it again.

4)-After doing the physical replacement, there are "initialize module" and "calibrate suspension" options on the scanner. I ran both, it went through several functions, and functioned correctly. I am sure that these just mirror what those with SDD have, but this is a convenient handheld device.

It seems there are not a lot of list members that have reported pump replacement, yet three companies are manufacturing and selling them. I assume there are more out there, but maybe they are just not list members. At any rate, not a big job. They strongly suggest replacing the relay at the same time, but the one they send is incorrect. There is a FORD part number on the OEM relay that you can enter on Rock Auto's web site to get a replacement made by HELLA for $5.00, plus $4.00 shipping. Locally, they are $20.00 or so, IF you can find one at Napa

 

Good to know and glad you got it fixed!
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