I realize the question is pretty broad but I need to get some useful input. My wife's 2004 XJ8 has an electronic problem that can be VERY expensive to correct and at it's age it may well be more than the car is worth despite it's otherwise great shape. Without going into details as to just what is going on I need to get information on the possibility of reprograming either one of 2 existing modules or salvage yard modules. I understand the need to match VIN #'s to specific unit part #'s as well as part # and VCATS #. Unfortunately most of the posts on this topic are pretty much into the weeds with few having actually successfully reprogramed a module, or even tried.

The car suddenly developed a communication problem between the instrument cluster module which is the gateway to the CAN system as I munderstand it and the ECM. It first flashed a CONFIG E error but still started and ran like a scalded dog even though it shouldn't have. The next day that message was gone only to be replaced with 2 more Config errors, an R and I believe an S and would no longer start. I was able to unlock the shift gate so I could get the car on a roll back and to the shop but since then there's been no agreed upon or targeted module to zero in on. We only know that the IP is NOT talking to the ECM and that there is no trace of damaged wiring, bad grounds, etc.

That leaves me with the possibility of just throwing very expensive parts at it with no certainty that one or the other will work or if in fact the real culprit......based on several erratic and repeated SDD scans.... is nothing more expensive than a poor connection at the back of the instrument cluster at what the schematic labels as IP6 where it communicates with the ECM.

So my question. Can a similar IP cluster and/or a similar but used ECM be reprogramed by way of SDD and if so who has done one or both at some point? Remember it's a 2004 XJ8 non-SC'd car built for the North American market.

 

First you need to understand the networks and what can be replaced and what cannot be a 'used' module without VID block concerns.

Much reading for you.

This a partial list of things I thought of. There is a lot of info to consider before swapping or replacing modules.

 

I appreciate the 'reading list' you linked to and had previously downloaded all but the last 2 in the list from other posts you've made on this sugject. The bottom line still remains the same and that is can it be done as I have over the past several years read all sorts of conflicting statements. Some have come from compnaies supposedly specializing in module repair/reprograming..

I went through a similar problem jusy a few months ago with a friend's 2001 XK8 when he was told that his ECM had crapped out. As it turned out in his case the real problem had been the replacement of a faulty O2 sensor with one that was incompatible with the others in the system and the mixed signals that caused was diagnosed as a bad ECM. After efforts to use 2 salvage ECM's that his shop was unable to make even start the car I was able...mostly through luck and some study of how to use my SDD ......to get the 2nd one to work even though I still had my doubts about it's complete compatabilty. It would start the car but it obviously didn't make the 02 sensor problem go away. We knew though that problem was not one related to an ECM !! A very long and time consuming run around the barn to end up where he had begun...bad 02 sensor readings. A problem that was solved by replacing the other 02 sensors with same make ones with the SAME RESISTENCE SPECS so that the ECM could make sense of the readings it was dealing with. For future reference for others who stumble here, remember that spec matching if your replacing 02 sensors as mix without match doesn't work.

If we take for a given that a person can buy a used but still working module that meets the part # and VCATS of the original part can it be reprogramed by a compotent Jaguar tecnician with 35 years of Jaguar specific experience? I'm in the dark with respect to the IP module as it appears to not have been troublesome based on the number of posts on this forum.

 

s

Motorcarman...hey don't take my earlier response as any sort of a rejection of your help. It wasn't. I have read your other posts on the topic and had previously downloaded from them many of the help topics you listed. I'm trying to come to a decision about just how much further to go with my wife's car before calling it a day and consigning it to a salvage yard. If the car was otherwise pretty used up that ould be an easy decision but it's still a solid car both inside and out and up until this started happening it was a very strong runner and a real pleasure to drive. That said there is a point where the probability of dropping anothe $2K + or even more into it makes no sense. I have my '99 XK8, a newer Genesis 5.0, and a couple of mid-60's hotrods so the XJ becomes sort of odd man out.

 

I did reprogram used ECM in my car with keeping all history from original one (that was not the cause of my problems however) My car has old generation architecture as yours with VID-blocks. But i would strongly recommend first to comprehensively diagnose your wirings and connections (high-currents as well) especially go through "christmas tree" bulletin to assure CAN-bus integrity. Modules' failures in these cars are 3-5% of causes from my experience.

PS for example my starter cable was damaged and it caused unstable performance of all electronics as battery does very important role even when car is running and relies only on alternator as could be seemed from the beginning.

 

The Jaguar cars with the VID block are much harder to diagnose and repair because of the complexity of the modules and networks.
The X308 was fairly simple compared to the X350.

 

I have the ECM com fault also. So far here is what I have found. I do have module faults but it is not the ECM. In my case the DSCM has partial internal shorts on each of the CAN bus lines. Also the same with my TCM. These are basically partially shorting out the ECM CAN bus. Jag indicates the car may run with many bus faults however programming any module will have errors or not be possible.
The pinpoint tests for the CAN bus will quickly diagnose these problems - although it will not show you which modules. The tests require 10k ohms to pass. In actual fact I think a good system will be in the meg ohm range - I do not have a good system to test that out on
I verified the shorts on the modules pins so it is not wiring or connector related.
Since you have the ECM com fail check the CAN+ and CAN- short to ground and then B+ at the Diagnostic connector - OBD port.. If you have a fail, disconnect the DSCM and see if the problem goes away. This disconnects the DSCM. ECU and TCM.
Check this far to begin - I will go a little further if you find a fault doing this,

 

The 2004 XJ8 is at a specialty shop that has been operating for years almost soley on high end European Jaguars, Mercedes, Porsches, etc. and their lead Jag tech has some 35 years with the brand. I'm sure he'd agree with motorcarman's statement about the 350's difficult programing regime and its compexity. One of the bit of info they've passd to me is that in trying to locate the cause of my problem one of the tests of the CAN system is the ohms resitance across the network. In my cars case that resitance is TOO LOW but they've been unable to find a cause that would lead them to suspect other than the ECM whichg evidently is one of the terminating ends. Perhaps motorcarman can shed some light on that.They say they checked as best they can short of disassembling half the car the connectors and grounds with no problems or obvious faults found.

One of the documents posted by motorcarman states pretty emphatically "In the event communications to the Engine Control Module (ECM) cannot be established or an error occurred durining programming and the ECM will no longer communicate with the WDS, DO NOT replace the ECM. (emphasis theirs) This argues against , at least initially, removing the ECM and sending off to be 'reprogramed by some distant outfit that may or may not be legit and nothing but a outfit that will charge you for an unnecessary 'rebuild' or sale of a "refurbushed unit".

They go on to describe in some detail as to how the in car "rectification" procedure should be carried out. That line makes me wonder how may module 'reprograming' companies aren't in fact doing exactly that.

 

All of the above is true! However the rectification process will not work with a bad bus. What is often missed is that the termination resistor compounds a problem with shorts in the other modules. Since the modules are in parallel this adds another path around the short. In my case adding the ECU to the DSCM reduces the bus resistance from 22K TO 11K. This happens because the 120 Ohm resistor goes across CAN+ and CAN-. It ties the two shorts in the DSCM together and reduces the resistance by 1/2. Also this happens in my TCM as well so my overall resistance drops to 5k.
When measuring the shorts in my modules they were both very close for the CAN+ and CAN- to ground. However they are not the same and are actually different paths. Therefore they add when measuring overall resistance.
Check the resistance on the actual DSCM pins. CAN+ to CAN- should be almost infinite and each to ground should be over 100K. Do the same for the TCM. Can also check your ECM if you want however my bet is that is just fine.
EXTRA INFO: My problem started when I went to update the ECM. Crapped out part way through and would not communicate, Also would not work with recovery mode. I did not consider bad buses, before programming, because the car was running fine. It was only after the fail that I started to check the buses. Tore the car apart to check everything before narrowing it down to the DSCM and TCM.

 

The shop finally came to the conclusion that it was the ECM that was the problem. They snt it to a shop they've used before named Module Experts which I believe is in Jacksonville, FL., and they got bad news. Yes, they did find a failure in the ECM but are unable to repair whatever that fault is and they have no refurbished unit available.

I'm totally lost as to why on the one hand we're told an ECM can not be programed to a car it did originally come from while at the same time being offerd refurbished unitws programed to work with our car. How does that work?

Jag techs on this very site have told us repeatedly that the VID blocks are the key. I assume that VID stands for vehicle identification since the stumbling block to reprograming appears to be the immobilizing function that acts as an anti-theft feature.

So 2 questions. First what other companies have memebers used to repair ECM's for the older cars which in my case is a 2004 XJ8? I need names to pass along to the shop working on my car. The second question is just what options do I have relative to finding a good ECM from a 2004 XJ8 that has all the same part #'s, etc.? Can such a unit be reprogramed or "refurbished" in some way?

 

With a good bus they can be reprogrammed. It looks like programming is possible as long as the shorts leave the bus over the 10k ohm minimum - even though this is meg ohms below where it should be.
The VID block is not lost/changed when updates are done to a module even when it craps out. However when programming a new module the other modules retrieve VID block info from the ECU. The ECU, on the other hand, queries all of the other modules to rebuild the VID block. So the buses and all their modules need to be functional.
As noted in my previous post a failed update made my ECU totally non reachable. My DSCM and TCM both have shorts. Rectification would not work. However I disconnected the DSCM and jumpered the CAN bus wires, made sure I had 14.2v at the OBD connector, and reprogrammed the update to get to the rectification procedure. The programming failed as expected BUT THE RECTIFICATION WORKED. My ECU is back fully functional. Jaguar indicates this is the only way to revive the ECU. It apparently can not be done out of the car. Therefore a rebuilder would see it as an non repairable module.