The shocks on my XJR (84K miles) defaulted to the firm mode and the "CATS System Fault" was displayed. This occurred after the car had sat in the parking lot at work for the day. There were no obvious precipitating events to cause this. A check of the codes with my AutoEnginuity (AE) revealed C1457 Accelerometer Front - Circuit Short To Ground, C1437 Accelerometer Rear - Circuit Short To Ground, and, a few days later, C1893 Rear Left Height Sensor, Open Circuit/Short Circuit to Ground. I reviewed the wiring diagram and can find no reason for this combination of faults. While the front and rear accelerometers share a common sensor voltage source and sensor ground in the ASM, I can see no reason why either of these would fail. The left-rear height sensor DTC adds more mystery to the issue.

I pulled the back seat cushion and seat back, and disconnected/reconnected all WABCO/ASM connections and related harness connections, but this had no impact. Note that this is a Southern California car and all electrical connections are bone dry and like new, both inside and out.

Having spent more time unsuccessfully chasing another electrical gremlin in the car than I would like to admit, even with AE, I am inclined to go with a coil-over-shock setup without spending days trying to solve this. While I can drive the car with the shocks in firm, there is no way others would ride with me. I have not been enamored with the R Sport suspension, especially over speed bumps and dip+turn combinations, where the ride is very choppy and un-Jaglike. I also don't want another component in the air suspension to go bad when I am on a road trip. My older Jags (SIIIs, XJS, X300) had great rides, certainly better than the R. Since I have an XK8 and XK to drive for sport, I want this car to ride more in the comfort mode while having the great performance of the R that I love.

Before I throw in the towel, I thought I would check to see if any others have had experience with these types of faults.

Dan

 

I have no direct experience of these faults, fortunately, however I can make some suggestions:

Clear all the codes

Disconnect battery and touch leads together for 10 secs to drain system of power.

Have battery tested for voltage drop under load.

Drive car and see which codes return

Check wiring and connector to rear height sensor.

Check height sensor for continuity

Replace height sensor

You may have a CAN fault-disconnect,reconnect relevant wiring connectors.

Others with more knowledge will be along shortly.

 

Since it's not only electrics but also CAN-bus I would also first erase the messages and see if and so which messages return. If there's no permanent error it will also reset the CATS system back to soft.

Guus

 

I have cleared the DTCs on multiple occasions, only to have them return.

I disconnected the battery cables, touched them together, and reinstalled them. The faults/DTCs remain.

While the battery is not new (manufactured in July 2009 per the code on the battery post), there are no DTCs that would indicate low battery voltage/power and there are none of the other usual signs of a failing battery.

I don't believe the issue is related to the LR height sensor per se since the associated DTC didn't appear until well after the two accelerometer-related faults occurred. The fact that the DTCs for the accelerometers occurred simultaneously leads me to think the issue is module-related since I doubt both accelerometers would go out at the same time and then be followed by a failure of the height sensor.

Dan

 

If you clear the DTC's they immediately appear again? Does the P1110 reset to P1000?

You're right that two failing height sensors at once is very unlikely.

Guus

 

Hi Dan,

It might be worth testing the battery voltage while cranking just to rule out sagging under load. Five years is a fairly long life in a Jaguar saloon...


Even though the electrical connectors appear clean, it would be worth cleaning all associated connectors and ground points, especially the connectors and ground for the ASM behind the rear seat, and also checking the harnesses for any signs of abrasion, pinching, etc. Sorry for the shotgun suggestions...

Please keep us informed.

Don

 

Re the P 1110 code, I don't clear it. I use AE to clear only the codes for the CATS/air suspension at this time.

I agree about the age of the battery. However, rather than test it, I plan on just installing a new one. I have had too many occasions when older batteries in my former Jags and other cars failed with little or no warning.

All of the connections on this car look brand new. There is no abrasion, corrosion, etc., certainly not those to the ASM. However, there is no harm in cleaning the connections.

Yes, the big question for me is why would both accelerometers indicate a fault at the same time. I plan to check for 5V power at the rear accelerometer (readily accessible in the trunk) so determine if the ASM is providing this.

Dan

 

And do the mentioned code clear okay or not and if they do clear do they appear again straight away?

Guus

 

They clear, but reset as soon as the car is restarted.

Dan

 

Dan,

What I've noticed on connectors on our '04 is not typical rust, but a thin whitish film, especially on the aluminum ground nuts and wire eyelet/ring terminals. Since some systems rely on fairly precise resistance/voltage measurements, any resistance can affect performance, and the resistances of multiple connectors in a circuit are cumulative. I'm not convinced that this is your problem, it's just something you can rule out so you might as well. Use a good zero-residue electrical contact cleaner spray to flush your connectors, and take care not to overtighten the nuts on the ground studs since several members have snapped their studs off.

Please keep us informed.

Don

 

Good news, bad news.

Good: I drove the car to work this morning and on my lunch hour. Drove like a buckboard. I hopped in the car to drive home - no CATS warning and shocks are back to normal.

Bad news: I don't know why. The only tangible thing I did yesterday was the battery-cable contact exercise.

Path forward: I cleared the codes and will drive the car as usual tomorrow. One stop will be to pick up a new battery for later installation. If the problem reappears, I'll post to this thread again. If it doesn't pop up again in a week, I'll post this as well.

Thanks for the input from all.

Dan

 

To close the loop on my experience, the ASM faults have not reappeared in ~10 days and the car rides normally. I continue to assume that it was clearing of the ASM memory that resolved the issue.

Dan

 

I have a 2004 x350 that also has a very hard ride.. The compressor comes on and goes back off as it should. The car does not loose air even if not driven for a week. Do the fault codes you all speak of appear in the dash message center or do they need to be read by a plug in code reader? The stiff ride is the only thing I really don't like about this car. Battery is new, but no hard reset has been done by me yet. Brandon

 

The DTCs do not appear in the message display area. You need to have the codes pulled by a dealer, Jag independent, or someone who has a reader for Jaguar-specific codes. Without these, it is shots in the dark trying to figure out your problem.

I will be curious to hear about what you find.

Dan

 

Hi Brandon,

Dan's right - you need to have the codes read with Jaguar-specific scanning equipment. You might search this forum for Mongoose and JLR SDD to read up on how you can set up a laptop at home to scan the codes yourself.

My impression is that your ECATS system is not operating properly, but it is possible that it is operating correctly but you don't care for its firmness under certain situations. I notice that ours can be harsh going over speed bumbs and potholes at speed. But I think this is normal.

As I understand the CATS or ECATS adaptive damping system, the default mode is Firm. The adaptive damping ride control, or Adaptive Damping Control Module (ADCM) is part of the Air Suspension Control Module (ASM or ASCM). The ADCM references signals from two vertical accelerometers, one at the front left corner inside the wheel arch liner, and the other in the rear luggage compartment (trunk/boot) "to the right of the Telematic stack." The ADCM receives lateral acceleration information from the Teves Mk25 braking control module over the CAN bus network. To switch the shocks to Soft mode, the ADCM sends a 400Hz Pulse Width Modulation (PWM) signal to the shocks.

You can download the Air Suspension section from the '04 XJ New Model Introduction Dealer Training manual at the link below. It won't make any of us experts on the air suspension, but it's the best explanation of the system I'm aware of.

http://www.mediafire.com/view/7rdkgg...on_Section.pdf

If your ECATS system is malfunctioning, it could be an accelerometer out of alignment, an electrical problem, or some other issue. Some problems trigger the CATS System Fault warning on the dash. I assume others may trigger a DTC.

Please keep us informed.

Cheers,

Don

 

Thanks for the info. My impression is the car rides like a wine cork on a rough sea... I was used to a fantastic ride in my 02 VDP and just assume this new ride is the direction Jaguar was headed for. The car will see very limited use in the future so it will be more important that it just looks good cruising around town in the SF Bay Area no real need to try to improve it at this point, I may get it scanned just for laughs though ;-))