I don't have any problems (he says, knocking on a piece of wood close by) but a question on how the air suspension works. Like most people I drive the same route every day, and part of that route involves stopping a a light for a fair amount of time (2-3 minutes). The ground is very level and I have noticed that if I put that car in neutral, and take my foot off the brake (the car doesn't roll) then after about 4 seconds the rear of the car rises 1-2" followed by the front rising a similiar amount. The car doesn't do this if I keep my foot on the brake or it is in gear. Is this the suspension calibrating itself or a sign of something else? Just an idle question....

Thanks

- Tim

 

Just to add to that, I have a 2004 VDP, and in the owners manual it says to place the shifter in neutral when stopped at a redlight or in traffic, etc... does anybody do that?

 

It really says that, i don't think that sounds too safe

 

I always put mine in neutral when I am stopped as I was told it lessens the strain on the torque converter. Countering that, some people say the wear and tear on the gearbox is higher if you keep taking it in and out of gear. YMMV

- Tim

 

I always thought that the air suspension had an attachment that sucked money out of your wallet.

 

While the below information relates to the XK series of vehicles, the same principles should apply. Hopefully this will answer your questions. This is copied out of the JTIS for a 2003 XK. The only difference that I can see is the XK uses a dampener, where the VDP is going to be using air adjustable shocks. The two can be thought of as the same parts.

Adaptive Damping

SystemDescription

The Adaptive Damping System available as an option, matches damping effect with vehicle driving forces, to provide optimum ride and handling performance.The system which is completely automatic and requires no drive input, comprises the following components:Four adaptive damping units installed in the normal shock absorber positions. These are identified by a harness connector incorporated in the top of each unit.An adaptive damping control module (ADCM) installed in the trunk adjacent to the battery.Two vertical movement sensors (accelerometers), one installed on the bulkhead below the air conditioning unit, the other in the trunk below the fuel tank.A lateral movement sensor (accelerometer) installed within the RH side false bulkhead.

Operation

The four adaptive damping units are simultaneously switched to either firm or soft setting to suit circumstances. When the vehicle is stationary, the system adopts the firm setting to minimize vehicle pitch during initial acceleration. From 8km/h (5mph) upwards, the system reverts to the soft setting until otherwise switched by the ADCM.On detecting cornering forces, the lateral sensor transits signals to the ADCM, which in turn switches the damping units to the firm setting, reducing vehicle roll-rate and improving wheel control.

On detection of a bump or depression in the road, the vertical sensors transmit signals to the ADCM, which in turn switches the damping units to the firm setting to minimize vehicle body movement.Under braking conditions, the ACDM, on receipt of a signal, commences calculation of vehicle deceleration. When deceleration exceeds a pre-determined threshold, the ADCM switches the damping units to the firm setting, reducing vehicle pitch rate and improving wheel control.Following completion of a cornering manoeuvre, negotiation of road surface undulations, or heavy braking, that has necessitated switching to the firm setting, the ADCM always returns the damping units to the soft setting.In the event of failure of the Adaptive Damping System, the damping units automatically revert to the Firm setting, ensuring that the vehicle remains safe to drive under all circumstances. The driver will be alerted to such a failure by illumination of a 'SUSPENSION FAULT' warning on the fascia message center and the amber warning light in the instrument cluster.

 

Hi I am new here,
Hawing problem with low milage 2000 Jaguar XKr - The adaptive suspension control keeps Locked all time in firm position - will not come off above 5Mph as it is supposed to do. No code - But suspension warning appair in the dash warning module after I driving a little. I believe all the shocks & their wirings/connectors are fine - have measured each shock valve resistance at the control unit connector (ADCM) in the trunk. Abot the same sesistance for all 4ea shocks. Module get +12v at both pins as per ref wiring dia, One stby and other is SW 12v. Brake SW pin works fine, got 12v when Off and 0v when brake is pressed. Ground is fine - no resistance.
Took the plastic cover off the (ADCM) - all dry & and nice there.
Is possible that the Accelerometers are bad? Do not know how to measure them. But this car had some side impact 2 yrs ago and was repaired.
In Ref to the speed signal - from where does the Adaptive control get the speed signal. Do not know how I can verify for presents of > 5Mph signal.
Anyway, any suggjestions what I should look at next.
Many thanks,
H. Tomasson

 

This is the info for the 2004 XJ taken from JTIS:-

The vehicle dynamic suspension is a passive air suspension system providing vehicle levelling independent of load. The system also improves the drag coefficiency by automatically lowering the vehicle for high speed driving.When driving at high speeds, the air suspension system will lower the vehicle to improve aerodynamics and vehicle stability. The suspension will automatically return the vehicle to the normal ride height when the vehicle slows.

NOTE:-
Speed lowering is disabled when towing. Only Jaguar approved towing equipment will inhibit this feature.

The air suspension system ensures that the vehicle is always at the correct ride height for varying load conditions.
The air suspension system automatically adjusts the amount of air in the air springs to level the vehicle. Air is supplied either from an air reservoir or a compressor. The compressor will run periodically to fill the air reservoir.
The air suspension module (ASM) controls the operation of the solenoids in the valve block. The front air springs are operated as a pair, the rear air springs are operated independently of each other. The ASM adjusts one axle at a time, for example, when lifting the vehicle the rear axle is controlled first; when lowering the vehicle the front axle is controlled first. This reduces headlamp glare during leveling operations.

The ASM uses two different filter rates. When stationery, a 'fast' filter allows the system to react quickly to payload changes. Whilst driving a 'slow' filter allows for compensation of the fuel level change but does not react to road inputs for example pot holes and speed bumps.

Suspension Height Sensors
Four suspension height sensors are provided which are mounted on the front and rear subframe assemblies. The suspension height sensors are linked to the suspension arms by drop link connections and secured by means of a spring clip.

NOTE:-
Suspension height sensors require calibration if removed/refitted or replaced.

Air Springs
Two derivatives of the air spring are available, comfort and sport, the sport having slightly smaller working volumes for higher spring rates.The air springs are complemented by two versions of damper assembly, passive and active.

CAUTION:
When removing and refitting the air spring and damper assemblys care must be taken to avoid damage to the internal seal assembly.

CAUTION:
When working on the air spring and damper assembly, ensure that no twisting occurs between the air spring top mounting and damper body. Twisting may result in damage to the air spring inner components.

A pressure retaining valve (PRV) is located in each air spring which retains sufficient pressure to protect the air spring membrane during service and handling.

NOTE:-
De-pressurization and re-pressurization of the air suspension system should be performed using the Jaguar approved diagnostic system prior to, and after, any work being carried out.

Solenoid Valve Block
The solenoid valve block contains five individual solenoid valves consisting of one per air spring and one for the vehicle reservoir. A pressure sensor is incorporated into the solenoid valve block and monitors air spring and reservoir pressure. The solenoid valve block is mounted on isolators to reduce valve operation noise. Pipe connections are provided for the front and rear air spring assemblies and also the reservoir and compressor. The compressor to valve block port and the rear air spring ports are 4 mm in diameter with the front air spring ports being 6 mm in diameter. Each of the solenoid valve block ports and air pipes are color coded (pink, blue, white, yellow, red and brown) for correct connection.

Reservoir
The reservoir has a volume of 4.5 liters with a maximum design pressure of 15 bar (218 psi). Dependent on load conditions this store of reserve air is sufficient for two full lifts. The system automatically replenishes the reservoir by way of the compressor.

Air Suspension Module
The air suspension module (ASM) is accessed from the right-hand side of the vehicle, behind the back of the rear seat. The ASM can be recognized by the 4 individually colored connectors (gold, grey, yellow and pink) and the WABCO emblazoned logo on the front of the module. ASM calibration is required when either a replacement module is fitted, or if any height sensors have been removed/refitted or replaced.

NOTE:-
If installing a new air suspension module it will be necessary to set the (ASM) into the customer mode using the Jaguar approved diagnostic system.

Compressor
The air compressor is located in the left-hand front wheel arch behind the bumper beam assembly. It contains an air filter, an integral regenerative air drier element plus an air exhaust solenoid valve. The compressor is isolated from the main body structure by 3 mounts, each incorporating a rubber bush and metal spring. The maximum pressure developed by the system is 15 bar (218 psi) with a compressor pressure relief valve fitted, set to relieve pressures above 17 Bar (247 psi). The compressor only operates whilst the engine is running. To guard against the compressor overheating the (ASM) may shut down the compressor to allow cooling to take place. Re-activation of the compressor depends on vehicle activity and is generally no longer than 120 seconds.

 

BuckMR2 - nice info/descriptive - thx.

 

If it is really a 2000 XKR than you don't have air suspension. My '98 XJR has just had the occasional fault occurring. I had the code read and it pointed to the vertical accelerometer. My friendly mechanic switched it with one of the other ones on the car as they have the same part number and, so far, the problem has gone away. I would recommend getting the codes read by a dealer to save you time.

Anyway, here is some info from the JTIS for the 2000 XKR that might be of use:

Three accelerometers sense vehicle body movement and generate an analogue voltage (+5V max.) output, which is proportional to the vehicle body movement.

These voltages are supplied to the Adaptive Damping Control Module (ADCM).

At 0g. (no movement of the body) each vertical accelerometer outputs approximately 2.5V steady voltage.

The lateral accelerometer outputs approximately 1.5V.

The voltage output due to body movement is proportional to acceleration in the acceleration axis, up to approximately 4.5V and down to approximately 0.5V.

The ADCM is hardwired to the Instrument Cluster. Should a fault occur, the ADCM grounds the System Error line which switches on the amber warning lamp and displays the message SUSPENSION FAILURE on the message centre.

Basic Checks

Before changing any component, refer to the circuit diagrams of the manual and check the continuity of relevant harness circuits; in some instances, the PDU will not differentiate between a faulty component and a damaged connection or wiring.

Check the System Error line from the ADCM to the Instrument Cluster - Fascia Harness pin FC025/006.

Check the Road Speed Output from the Instrument Cluster to the ADCM - Fascia Harness pin FC026/007.

Check any relevant connections to confirm that the connection is electrically sound and that a terminal pin has not been pushed back into the connector shell, ie. not making a connection to its mating pin / socket.

Check the following fuses in the luggage compartment fusebox: Fuse No. 2 (20A) and Fuse No. 4 (5A).

Regards

Richard

 

The six speed ZF 6HP26 transmission used in the 2004-2009 XJ is supposed to automatically decouple the engine from the transmission at a stop. This is supposed to save fuel. I would imagine it achieves the exact same thing as the driver shifting into neutral. In other words, don't bother, although I have a habit of doing it anyway. I really wouldn't worry about wear and tear -- the friction materials undergo a thousand times more heat and wear when, for example, you kickdown from 2nd gear to first under throttle.

This transmission is used in many different vehicles. More recently, Hyundai (!!!) started putting it their cars as well. Read all about it...
http://www.audiworld.com/news/00/zf/content.shtml

Mike

 

Good details here, Thank you Much !
Correct the 2000 kxr does not have air suspension - But very good detils on the air system by BuckMR2.

Thnx u102768/Richard for very good details on the Adaptive Damping system.
I suspect problem with the vertical accelerometers as the car had some impact/damage to the L/H side few yrs back
then for parked in garage for some time - until repaired.
From your details - Will do som excersixe on the accelerometers them tonight. Try to measure their voltage output.
I believe the front vertical accelerometer is located somwhere at the firewall - front of the radio.
I have already been looking at the rear one - under the gas tank.
Strange - not been able to extract fail code Using OTC Genisys System 2 Scanner - At least not related to this problem.
Car/shocks just stuck in the firm mode (default mode) and stay there no matter what.

H. Tomasson

 

High speed lowering does not occur until a speed of 105mph is reached. At speeds above 105mph the car will be lowered 15mm.

 

It looks like your scanner is a generic OBD-II scanner. You need a Jaguar specific one to pull other codes which is why I recommended going to a dealer. The Auto Enginuity Scan Tool is an after market one that can read the codes but it is not cheap!

 

My Scanner has specific OTC Jaguar Software loaded, I can, I can for example go into each and every engine
sensors, verify their functionality and look at their individual output at real time. (Scope)
But Yes, I wish could find someone up here that have proper dealer type scanner for the Jag.

Start to think there is a problem with the speed/sense signal input to the ADCM
But it appear that the cruse control is also not fully functional either.
Have not yet reviewed the wiring diagram to see if the ADCM & Cruse shares the same speed signal input.
How I understand the manual. The Adaptive shock system stays in firm mode below 8Kmh (5Mph)
Above the 8Kmh the ADCM switches to soft mode, and start modulating by on/off-ing the shock solenoids based on the accelerometers signal inputs.
H. Tomasson

 

Problem found - Rear Vertical Accellerometer fault with steady 0.6V output
Hence the front Vertical Accelerometer measure 1.5V..

 

I have a 2004 XJR and it seems that this air suspension is more trouble than it is worth. Is there a company making replacement suspension for the 2004 XJR ? Something like a coil over shock replacement system?

 

I don't. It will kill the transmission.

 

Indeed they do put the ZF 6HP26 on some Hyundai; my wife has it on her Genesis 4.6. The Tau engine knocks out 385hp in the 4.6 and 429hp on the 5 litre, all with natural aspiration no less! I have noticed that the gear changes in the Hyundai are not as silky smooth as my XJ, but the car is pretty amazing given its about half the cost of my VDP.

 

There are about 3 companies making spring/shocks for the 2004 - 2008 models.

Arnott and Blackdog are two, will post the other name on Monday.