I guess this is a rite of passage for Jag owners. Please help me get through it with my wits intact

My '07 XJR is now sitting (on 4 drive on ramps) with full weight on all 4 wheels. The right rear strut is inflated; all the rest are down

Is there a way of getting all four struts to fill (without an SSD system)?

Has the ASU (air suspension control unit) possibly gone nuts?

OK - for those of you who want to join the fun:

This saga began with the rear end drooping, then the front end following suit. I measured "suspension res pressure" using a scanner and found ~7.0 bar, and therefore figured the compressor was duff (supposed to be something like 13 bar??).

So, I put the andy ring kit in (the original ring looked fine BTW, then retested and same 7.0 bar. I then removed/inspected/cleaned the compressor exhaust solenoid valve and pressure relief valve (both were in perfect condition). Same result. Cleaned compressor ground (behind LH headlight): same result

So, I isolated the compressor, and powered it with an external battery. The scanner showed 13 bar within 20 seconds. So, I don't believe the compressor capacity is at fault

I then pulled fuse 6 (40A air compressor; underhood), released air pressure, and retested; same result (this procedure from a vaguely mystical forum thread). Ditto fuse 6 and fuse 12 (trunk); same result. I believe these steps are supposed? to reset ASU? Then I swapped the compressor relay (R1); same result

I then loosened and tested the height sensors, using the scan gauge. All seems good (correct values)

Then, following another forum thread (clogged sunroof drains corrode ASU connectors, etc), I pulled the rear seat (arghhhh) and rear trim, inspected and cleaned all the ASU connectors and ground point (which is outboard RH rear seat area; 8 mm stud?). All seemed perfect

Finally (now 10 hours in), I retested, and just the RH rear corner raised. Have I scrambled up the ASU?

Appreciate any advice from forum gurus

 

Have you done what I suggested ie car on ground, run engine, drive around?

 

Hi
I disconnected the battery. Reset the suspension. Car started to inflate the suspension. Pump very noisy. After several minutes the osr deflated again, but 48 hours later and the osf is still inflated. It's going to the Jag specialist tomorrow for the Andy kit and a thorough check over...I had similar issues with my XJ8. Replaced the pump and a height sensor. Problem solved.

 

Thanks all for suggestions. I will follow and report

Meirion: Weight is on 4 wheels. Given your suggestion, I may try to (somehow) manually pressurize the struts, and take it for a drive. Right now three wheels are well up into the fender wells!

Dave: I'll disconnect battery and give that a try. Ill also recheck all three height sensors

All: Checking my scanner this AM, looks as if the system has lost some pressure overnight. So, at root, I believe there is a leak somewhere.
I did spray soapy water on all the connections I could find, and listened to the struts with a stethoscope (hence putting the car on 4 ramps so I could get underneath with weight on the wheels). No hissing to be heard
I may try to isolate each strut on turn with an 1/8" pipe cap? and see if I can isolate the leak
Also, I don't know why the ASU won't seem to command the compressor to bring pressure above 7 bar, though an archived forum thread ("Playing with SDD and Air suspension") by Xag in the Netherlands seems to indicate that this may be normal, somehow. As you may have noted above, I can manually run the compressor and it will bring system pressure up to 13 bar within 20 seconds.I say "system pressure", as the pressure sensor is in the valve block - not the res tank

 

Here are some pics:








Suspension Compressor



Stylin at Glacier Lodge last summer



Idaho Lunch Stop

Up on ramps; Suspension Drooped



Trunk Suspension Res; Control Block



Rear Seat Out; ASU Black Box

 

My next suggestion is as follows:

With ign and engine off.

Depressurise system by cracking a joint in pipework eg valve block.

disconnect batt and touch leads together for one min.

Reconnect batt.

Tighten joint in pipework.

Run engine.

This has worked before but no gaurantee it will work for you.

 

OK - Quick Update

Thanks for suggestions

Basically, I'm still stuck. Appreciate any further advice.

BTW, I am going to proceed now with disassembly, pull struts, and have all four rebuilt (they are NLA sport shocks). I will be renewing all suspension joints and bushings in the meantime, and having new tires mounted once I refinish wheels. I will reassemble with new struts and hope that i can get the car to raise sufficiently to test drive

- Hard reset per Meirion (above); drained all residual air pr all lines

- Retest; again raises RR corner only

- Sealed off feed line to LR strut; retest: no change (hoping LR strut leaking and therefore sealing would direct air to front struts

- Jack LR corner to same height as RR; retest: no change (put jack stand in place to hold height)

- Jack front end to normal road height both sides: retest: no change (front struts still not filling)

- Cannot drive vehicle to see if that would help (too low; esp front wheels cannot turn at all w/o hitting fender)

 

If only we could read the program in the ASU!

Any IT 'nerds' out there?

 

You could try taking the pipe off the valve block and some how supply air into the pipe this may raise one of the front ones if it does quickly refit the pipe to the block then do the other side might be worth a try

 

I am now proceeding with suspension rebuild

Clifton - Your idea is sound, though my monkeying around with the air suspension system indicates that an isolation valve would be required (as air pressure is high, but volume is low). Most shop air (eg, mine) is < 110 PSI (~ 7 bar), which is at the v bottom of the required pressure range

There is a forum member who devised such a set up, complete with a 250 PSI (~18 bar) gauge, and had it on loan to others a few years ago (according to an old thread I came across on this forum)

I now think that my Jag ASU somehow lost its suspension height parameters while sitting over the last year or so (while I built up the patience to tackle fixing it)