Good Morning,


I have pulled up several threads on this which suggest using a diagnostic tool in order to obtain a fault code. I have a scanner, but my problem is that when I scan the adaptive suspension system, the scanner tells me that it can't communicate with the ECU. It is, however, able to communicate with the car's other systems. Would this suggest that the ADCM module in the trunk is bad? I may bite the bullet and try another one to see if this fixes the problem.

I have confirmed that the fuses are good, the module is connected, and at least the front shock wires are connected.

Pulling the fuse gets rid of the code but of course the car is in stiff mode (wish there was a way to default it to normal mode).

Thanks for any suggestions.


Rob

 

More likely a scanner issue, especially if you are using one of the iCarsoft units. My i930 can be unpredictable, sometimes able to connect with certain modules and sometimes not. While it has been helpful during the 3+ years I have owned it, I always warn others to be prepared to return it to the seller if they opt to purchase one....

And your scanner simply may not have the ability to connect to your adaptive suspension system. When you run the unit's automatic test on your vehicle, what modules are listed on the screen?

 

Dang ; I just bought an i930 mainly for this issue (and for future use). I don't have it with me now, but quite a few systems come up with the automatic scan, but the adaptive suspension will not come up with the automatic scan. To find and scan that system, I have to perform a manual scan.

 

Also, my dad has a wrecked 2002 XK8 with 17k miles that we use for parts. If needed, any reason why I couldn't replace the electronic shocks with the ones from that car and just unplug the control unit?

 

Jon 89, the following systems come up with the automatic scan:

Engine control module
Transmission control module
Instrument pack
Driver's door module
Driver's seat module
Passenger door module
Passenger seat module
Passenger head restraint
Driver's head restraint
Security locking module
Restraints control module
Key transponder module


Does this seem about right? I bought this scanner primarily to scan the adaptive suspension for now, but unfortunately it's not coming up.

 

Yes, putting standard non adaptive shocks and unplugging the module is a common solution, especially considering the cost of the adaptive shocks.

I’m not sure I would go to all that trouble and use 20 year old shocks though. A set of standard shocks is not all that expensive, considering.

 

But what is the "code" you are getting?

To default the shocks to soft mode they need a constant 12v supply - on = soft, off = hard.

AFAIK the adaptive suspension module is a standalone unit and isn't connected to any of the data busses on the car - this would explain why the module isn't recognised - it physically isn't connected.

The warning message on the instrument pack is triggered by a dedicated fault wire from the module - this is why if you unplug it the message goes away and the shocks default to OV hard.

 

Dibbit, I am not getting a code. From the scanner menu, I can manually find the adaptive suspension system, but when I try to scan it, I get the message "unable to connect to the ECU".

Great explanation on the system. If there was a tweak I could make to put the system back into soft mode, that would be great.


Rob

 

When I purchased the scanner, I was under the impression from the description that it could give me a code for the adaptive suspension. But maybe I am mistaken if it is a standalone unit.

 

I don't think that my i930 has ever displayed the adaptive shocks module as something it can detect and read when it goes through the automatic scan function....

 

That's correct ; my scanner doesn't detect the system automatically, which I thought that it would. So where should I start to find out what the problem is....the dealer or an independent shop? My next step at home is to check the wires going to the rear shocks.

 

The suspension module is connected to a communication bus, it is just on the old SCP bus rather than CAN like a lot of the other modules. I can say that it is fiddly to connect to even with SDD.

 

Thanks for the replies. I'll look into it, but I may just get 4 new non adaptive Bilstein's and be done with it. One of the best things I did to an XJ that I used to own was replace the air shocks with springs.

 

Are you getting the "suspension fault" message (or whatever it says) on the dashboard? How do you know there is a fault?

 

Yes, "suspension fault" message on the instrument cluster. It's also riding notably stiffer.

 

If you look at the electrical guide it shows what values to expect at the different sensor connections at the adaptive damping module - you could test those.

I think I would be checking all the connections between the sensors and the adaptive damper module as it could just be a bad or missing connection. You've got nothing to lose if you are thinking of just ditching the system anyway. Otherwise you could just wire up a switch direct to the shock absorbers, and switch them manually - again nothing to lose if you are thinking of junking them.

My 2001 XKR has CATS, so I will be following this with interest.

 

The module is documented as being on the old ISO-9141 serial bus:



From memory, there were posts recently about this system and the eventual conclusion was a set of frayed wires to a rear shock, causing a short circuit. With the help of the documentation, maybe you can check resistance to each shock from the control module end of the harness and see if anything obvious comes up. That system seems to be generally reliable, and these shocks generally durable. It is probably worth putting in a bit more investigation time before writing it off.

From the electrical guide, Fig 06.3:

 

Thank you for the replies ; I will check the wiring and connections first.


Rob

 

Does anyone know how I access the connectors to the rear shocks? I wasn't sure whether go to under the car or from the inside.


Thanks,

Rob

 

Well, to answer my question above, unfortunately access to the connectors appears to be only possible with the shock removed.

One other question. Dibbit, you mentioned a switch to supply a 12 volt supply directly to the shocks keeping them in soft mode. Would the best way to do this be splicing into the shock wires at the harness coming from the ADCM module and then connecting to the battery?


Rob