My 2000 XKR with 50k miles was bottoming out in dips and Jaguar service recommended replacing front coil springs and electric shocks. I agreed new coil springs needed but suspected the shocks were still okay considering the mileage and the car drove silky smoothly and did not have an faults. In my troubleshooting, I tried unplugging the front shocks and that put them into default / firm mode and Suspension Fault code came on so I knew they were working. Curiously when I plugged the shocks back in the Suspension Fault code would not go off and stayed in firm mode. At this point I decided to go with Jaguar recommendation and replaced springs and shocks with Bilstein electric shocks. Now Suspension Fault code is STILL ON! Back to Jaguar service and here are their notes:

"50658 dupl. fault. ch and clear dtc - multiple shock failures and mod. power short to grn. ch fuses - all ok. pin out mod and shocks- all readings are in spec. susp faulty (ACD susp control) module. $612.53 client declined"

I bought a used ACD module and plugged it in, left the battery disconnected overnight and this morning still getting Suspension Fault message. Suspect the used module might be bad and am considering buying a new ACD module for $400 (yikes) and plugin it in myself saving $200.

Does anyone know if the new ACD module needs to be programmed after installation or should it work out of the box?

 

You need to get the actual diagnostic code(s) so you can do a better search. Hopefully, you can call them back and ask for that information.

You can always try the "hard reset" procedure, but it is unlikely to do any better then leaving the car off the battery overnight. $0 to try it, though.

For the module, check the VCATS sticker near the spare tire well. If the module is listed on there, it means the ECU is checking for versions. If the new module has a newer version than on the sticker, your ECU will have to be told it is OK to use...

Best of luck, keep us posted.

 

Thanks fmertz! I called Jaguar and they said the diag codes printout has not been scanned into the car record yet and to call back later in the week. He said there were faults showing with 3 shocks, yet in doing a pin test he found no issues. I'll post the codes when I get them.

I checked the VCATS sticker and sure enough the ACD is there: LJA1970AB/104 the original and used modules only show LJA1970AB/XXX. Starting to feel like I'll need to bit the bullet and pay Jaguar to do this.

 

Could also be harness damage. There is documentation for these modules in the electrical guides on jagrepair.com. The pinout should be documented. You should be able to trace the continuity between the control modules and the shocks. Seeing that you have 3 shocks at fault, it seems unlikely there is damage close to each of the 3 shocks, but more likely where these harnesses meet. Has there been unusual activity or other repairs in some area of the car? Or maybe water near where the module is? If you have 2 modules and no opportunity to return them, you can possibly open one and check for evidence of damage. Folks keep referring to ASI for module repair, maybe give them a call and see if a repair is more competitive. A repaired module would not need re-programming...

Another thing: double check the part# for the new shocks, just in case you have something somehow incompatible (unlikely).

 

But the pin to pin test showed no issues so if there was harness damage wouldn't that show up?

No other work BUT when retracing my steps, the fault code first appeared when I disconnected the original shocks. I later reconnected them and the fault code disappeared. I recall doing that a 2nd time but I MAY have disconnected the shocks with the car running. I know this would be a total bonehead move and I can't believe I'd do it but I know I was rushing to take my daughter somewhere. Again, not sure but I may have done this which would have damaged the module I'm guessing. I recall the fault staying on ever since.

The replacement used module gives the same fault code but it might be for a different reason such as the version # you mentioned. I don't see any signs of water damage. Perhaps Jaguar can reprogram the ECU for this module. I might ask them to try before buying a new module.


I'm pretty certain I got the right part number. I shopped around since they are so darn expensive and everywhere recommended this model. 2000 Jaguar XK8 Bilstein Shock Absorber Bilstein MJB2140EB

 

Jaguar got back to me on the diagnostic codes. They are:

C1516
C1424
C1419
C1427

 

The last 3 are "open circuit" errors, meaning the control module thinks the shocks are not connected, or resistance is too high. BTW, errors are for both front, and right rear. I believe the fact that the control module is able to produce error codes likely means it works.

Can you check the resistance on the shocks? Do you still have the old ones to compare? The forum seems to suggest good shocks have a resistance of a few Ohms (6). If the shocks read OK, you might have to do the same measurement at the harness at the side of the control module. If the shock resistance reads too high, they would likely be the problem.

 

Fmertz is right,
I would install the old control module, clear the codes and see what happens.......................

 

I measured the original fronts at 5.5 ohms and the new Bilsteins at 5.3 ohms which seems close enough to not pose a problem. If the module is ok then I think that leaves the harness (or several broken wires) but Jaguar said they did a pin to pin test that passed within spec. I'm going to take the car back to Jaguar with the used replacement module and see if they get any new clues. Desparate to fix as the car is not nearly as fun to drive always in firm mode.

I greatly appreciate your help!

 

Its curious, till you unplugged the shocks all worked fine.................................

 

Update: Jaguar went through entire wiring and found no problems from ACD module, harnesses up to and including the front shocks. @fmertz, they said the ACD is working properly just as you surmised. They found an open circuit to the right rear shock and checked the wiring as high up into the cavity as they can and it's ok. They suspect the shock is bad. They have no explanation for the open circuit faults on the front shocks as they are certain the shocks and wiring are good -- but they did say its possible the module is confused by the right rear open circuit. Of course if I only replace 1 shock the car may not balance so looking at both. After doing some quick research it looks like replacing the rear shocks is much more difficult than the fronts so I'm hesitant to do this myself. My costs on this are approaching 1/3 the car's value...but dammit I love the car!

Has anyone heard of the ACM giving a fault in error? I'd hate to replace the rear shocks only to still have this problem.

 

Indeed... I unplugged the front shocks with car running (which unfortunately is a possibility), maybe a burst of extra voltage went to rear shocks and blew one out. That's all I can guess. Otherwise, it could be just a coincidence on timing.

 

According to your header information, you may live in North Carolina. Tell me where and I may be able to point you to a great indie repair shop that will be less costly than the dealership and more thorough as well....

 

Hmm, if you are willing to go through the trouble, you could probably test this. Identify the pins on the harness (control module side) going to the rear shock identified as open circuit, and work out a home made wiring to one of the old shocks so the control module sees the 6 Ohms it expects.

Separately, double check the harness connection to the control module for bent pins, or even consider bending the pins a bit for better contact.

It is also possible the module is functional from a digital standpoint (it can "talk" over the data bus and run it's diagnostic), but is somehow burnt in terms of shock control circuits (consequence of unplugging it live). As you have a spare module, you might want to reach out to a repair service like ASI to see if they can come up with a repair/pricing strategy that works for everyone. Even consider sending them both modules at once so the best one can be identified.

 

Have you cleared the codes?

 

I live in Cary and would greatly appreciate a referral.

 

Great suggestion!

Per Jaguar, my original and the 2nd used module are behaving the same -- give same codes and Jaguar has ruled that out as a problem. But will keep this in mind.

 

Yes, Jaguar cleared DTC

 

Sure?

 

I have not darkened the door of Jaguar Cary (formerly Leith Jaguar) in years. They simply do not have the master techs who know our older vehicles and have the experience to work on them properly. Like most Jaguar dealerships these days, they are staffed and geared for the Tata-era vehicles. Jaguar Greensboro still has a couple of master techs with more than 30 years of experience (Nhao Haboon and Georgiy Koshelev) and on the rare occasions when I need a dealership's assistance, that is where I go. Nhao and Georgiy make it well worth the drive....

The best local Jaguar indie shop in our area is Flying Circus English Cars in Durham, owned by Toby Briggs. Toby is one of the kindest, most knowledgeable British car enthusiasts I have ever met. He has given me free advice over the phone many times during the past six or seven years and whenever I reach my DIY limit on a repair that stumps me on either of our Jaguars, I take them to him. His prices are very fair and he will take the time to explain to you exactly what he found and the various courses of action that you should consider....

Call him at (919) 596-4250. His customer service skills and diagnostic capabilities for our older Jaguars blow Jaguar Cary away....