The air suspension of my X350 seems to be faulty.
Its rear has gone down, but the instrument cluster does not show an error message.

The compressor was checked and runs fine when 12V are put on, but during driving it does not work.
The ASM or ASU seems to be in function as well, because after starting the engine, the ASM presents +13V on PIN 12 of connector CR91 (still a mystery).



But the R1 relay (air suspension relay) of the front power distribution fuse box (Reyesl published a PDF here) constantly gets +12V on PIN 3 and no current on any other PIN no matter if the engine has been started or not.



I swapped R1 and R2 and checked low beam and high beam to ensure that R1 is not the culprit.
Time to check the downside of the front power distribution fuse box.



The incoming +12V cable connector from the ASM is EC40-1.
The outgoing +12V cable connector to the compressor is EC32-2.
The problem is I cannot check them because I cannot lift up the front power distribution fuse box far enough.



The harness is too short and getting there from below could be very laborious.



Do you know how to check the lower connectors of the front power distribution fuse box ?

Maybe the ASM gets stuck in an unfinished check procedure and therefore cannot present any error code.

The vent solenoid valve of the compressor could also be the trigger of this fault.
I did not dare to put any test current to its connectors.
How would you check the vent solenoid valve and is there any way to put it back to order ?

Thanks




R1 is back in the front power distribution fuse box.

 

Peculiar !! If the system has flagged nothing, it must think the suspension is at the correct height, so suspicion must fall on the height sensors. Other thing is you maybe need the sensor values recalibrating. This is a shop job with the relevant Jaguar software on a lap-top. The laptop is plugged in to the diagnostics socket and then used to raise the car to the correct height front and rear, and the system then 'knows" what the correct height sensor outputs are.

 

Hi LeoJagger,

In addition to Fraser's good input, not that the compressor runs at start-up to pressurize the system, then it will not run again until needed, and only then when the vehicle is traveling at 25mph or faster (if I recall correctly). Once the vehicle speed drops below 18mph, the compressor is once again disabled (again, off the top of my head).

Cheers,

Don

 

Yes, Don B is right although I'm not sure about the minimum speed though My 2003.5 technical notes just says "above a pre-defined speed the compressor is used to raise the vehicle height".

Also the compressor will only run for two minutes. If the reservoir is not up to pressure in that time, a fault will be flagged. Inability to recharge the reservoir is normally an indication the compressor piston seal is starting to wear out.

I reckon a recalibration of the vehicle height is needed. Anything "funny" happen to the car recently ?

 

Thanks for your quick response. I am quite sure the compressor doesn't run during driving, the whole system seems to be 'off line' as there is no chassis error code displayed.

And yes, something funny happened to the car: After not being driven for 2 months it was towed.
Driving it again I realized that the left side was about 1 inch lower then the right side.
I released the air from the front suspension bags on a flat surface to even the chassis and expected that it would go up again after starting the engine.
But it took about 30 miles driving before an appropriate error message 'chassis too low' was displayed. Soon the compressor began to work and the front was lifted by its own struts to an even position.
The ride was soft and smooth again.
On the next morning the front was 2 inches down on both sides. The suspension was hardened but after one hour of driving everything had gone back to normal again.
That behavior was repeated two times before the whole air suspension system ceases to function at all. Since then, no chassis error code appeared.

 

What are you using to read the codes?

 

A regular OBD2 reader will not pull the chassis codes for the air suspension system. Only dealer level diagnostic software will be able to obtain them.

 

Sorry, I didn't mean OBD error code, what I wanted to say is that there was no error message displayed on the instrument cluster.

I use Ford VCM (Focom), there is an ASM section but it does not deliver any code.
As soon as I get any error codes from the workshop I will post it here.

Thanks

 

Hi Fraser,

Just got home from our son's college graduation and checked my copy of the Jaguar Service Training 2004 New Model Year New XJ Technical Introduction manual. Regarding compressor operation after the initial 2-minute run at start-up and the vehicle is in motion, page 7-13 states:

"In the majority of cases the compressor will only run when the vehicle is moving above 25mph (40 km/h) and will be inhibited when the vehicle speed is lower than 18mph (30km/h)."

I will be curious if your manual gives different speeds. I think we've noted at least one prior difference between the North America and U.K. manuals.

Cheers,

Don

 

Hi Don

All I have is a set of 2003.5 Technical Notes, not a 2004 Service Training Manual, which obviously is a later document, so yours will be correct.

 

To add to Don's wisdom here - when the compressor is running when the vehicle is traveling at speed (above 25 MPH) odds are your not going to hear it engage or run (unless you have a scanner hooked up) showing the compressor as "active".

Even when starting the car (if the compressor needs to re-pressurize the struts) you should hardly hear it run (unless your listening for it)

 

Yesterday I found 04 XJR Front End Suspension On The Ground - No Codes!
Maybe this is a similar case and the rear power fuse box can't deliver error codes any more.
I'll re-check the ASM again.

Thanks

 

Peter Brecklinghaus of british car service, Essen found a workaround:
R7, which contains SSP4 (Switched System Power 4) relay, should trigger the ASM to stance mode over fuse 12.
But there were no +12V on fuse 12, so the ASM stayed asleep.



He carefully gave 12V B+ to fuse 12 for a second when the ignition was on.
(If you plan to DIY better know what you are doing and use a cable protection fuse under 10 Ampere.)



The ASM began to initialize and check. Next thing he did was to start the engine.
The compressor behind the left front bumper gnarled and soon the car was lifted onto its normal position.
A short test drive showed no functional disorders.
Unfortunately this procedure has to be repeated after the car was parked for more than 30 minutes and the ASM has fallen into sleep mode again.

So a defective relay (R7) kept the ASM in its koma.
Because it cannot be replaced Jaguar calls it a 'Non serviceable PCB relay'.
That means a new rear power fuse box is needed.



But who is responsible for the death of R7 ?
A loose connection of a defective clamp on the minus pole is under suspicion.



It was not possible to tighten this tinny looking clamp any more, so it was exchanged for a more solid model.



What else can we do to protect the poorly buffered controllers in the Jaguar electric circuit ?
We plan to install a capacitor.
There are some available at Amazon which are suited for the support of stereo equipment:

US: Robot Check

UK : Amazon.co.uk: capacitor farad

I will buy a simple one with 1 plus and 1 minus terminal.
Thanks to Leedsman for pointing that out.
What is your opinion on that ?

Thanks to the contributors !

 

Hi LeoJagger,

Good work tracking down the defective R7! If you can access the solder terminals of that relay, you may be able to find a suitable replacement from an electronics supplier such as Mouser or DigiKey - I'm not sure what the equivalent supplier would be in Germany, but I'm sure there is at least one.


There is quite a bit of information online about adding one or more super capacitors to an automotive electrical system (or even replacing the battery entirely). Here's just one example:


I have not tried this myself, but it is certainly intriguing. Please keep us informed!

Cheers,

Don

 

Huh? I have compressors running all the time sitting still, slow speed in parking lot etc.... Do tell
even if it has a asm section in ford software, it doesnt meen it will talk to jaguar software. Hell sometimes jag software wont talk to jag software

 

Hi Brutal, nice to see you are still with us !

 

"That means a new rear power fuse box is needed."


A number of x350's are being scrapped in the UK and the parts are for sale on E bay.

This is one of the cheaper breakers:Jag-dna

 

Hi all,

thanks for your feedback.
For the X350 there are two different rear power distribution fuse boxes available :

2W93-14N023-BC
2W93-14N025-BC

Could you please tell me which one is appropriate for a XJR build in 10/2003 ?
______________________

Brutal, I learned that the X350 is more or less a Ford.
The sections of Focom that throw error codes are :

Steuereinheit Fehler
---------------------------------------------------------------------- -------
EPB - Elektronische Parkbremse 0
RCM - Airbag Steuergerät 0
GEM - Allgemeines Elektromodul (nur ISO9141) 13
DSM - Fahrersitz Modul 1
PAM - Parkassistent Modul II 4
REM - Hinten Elektronikmodul 10
DDM - Fahrertür Modul 4
RAD - Radio / Audio System-Modul 0
NAV - Navigation (nur CAN-BUS) 0
ASM - Was still in sleep mode
------------------------------------------------------------------------------

Thanks

 

These circuits do not work when SSP relay 4 (inside non serviceable PCB relay R7 of the rear power distribution fuse box) is defective:

94 LH REAR FOOTWELL LAMP
95 RH REAR FOOTWELL LAMP
96 LH REAR ASSIST HANDLE (MAP LAMP, COURTESY LAMP)
97 RH REAR ASSIST HANDLE (MAP LAMP, COURTESY LAMP)
98 Air Suspension System
99 Rear Seat Heaters
100 Rear Seat Heaters

 

Hi guys i have been reading this with great intrest and wondered if anyone else used the "rear boot" fusebox replacement with success?
i have the symtoms of "fault light on" but cannot pull any code.
symptom, morning start and drive car no problem, about an hour later light on?
but no code coming up on scanner, no hight differance, just to add ythe car has sat from the previouse morning or even two days before i use it, and the above looks like the only solution i have comee accross, any aadditions or advice would be more than welcome.
And a big thank you to all who contributed to this subject