1. Definitely checked open circuit
2. Have definitely checked short circuit
3. I have replaced the ABS module with 4 known working modules of different model numbers. Experienced the same symptoms with all of them.
4. I also tested with a replacement ECM and nothing changed during that time.


The only code that the car has produced is the P1637, and its presence does indeed turn on the check engine light.

So you are thinking it is one of the three modules in the engine bay? The ABS, TCM, or ECM? If I have replaced two of the three then logic would lead me to believe that I have a TCM issue?


Also, I thought it likely went without saying, but the ABS / TRAC warning lights are constantly on in my car.

 

I don't know how it could be the TCM, and there are 5 modules on the bus, nothing special about those in the engine compartment from the bus perspective (maybe from a corrosion perspective, but you checked this). The other modules, TCM, INST and the illumination module (passive), appear to have no role except the INST reports your ABS/TRAC problem caused by the loss of the ABS token. From experience, once the bus loses the token, the code is set. The network monitor in the ECM provides the watchdog function, I believe, when the ABS token disappears (or it thinks the token disappears).

Frankly, at this point, it seems like a CAN sniffer is your best option to determine what is happening (i.e. ABS token comes from the ABS, if it doesn't show up, but all of the other ABS messages show up, that's your problem, etc). This seems preferable to replacing modules repeatedly once you have verified connectivity. Have any options for that?

 

I agree that a CAN sniffer is likely the only way forward. I don't have access to one, I will have to purchase one and have it shipped to me.

I was hoping that I could solve this problem and avoid buying one, so I could make one by hand in the future, but I wasn't able to resolve this in time

 

@crbass

I think my biggest problem right now is not understanding the conditions for triggering this code.

You have said many times that this is a result of the ABS sending a CAN message to the ECM with a token.
If this token is missing on several of the cycles the ECM may flag this and emit the P1637. Does this sound correct?


Now the ways that this could happen is truly what I am interesting in thinking about. Let us say that I receive my can bus sniffer and open wireshark and see that the abs token message is missing often enough for the ecm to flag it and emit the P1637. What does that really tell us?

Physically we have checked that the can bus wires are sound with no shorts and no interrupts. I achieved this by testing the voltages and resistances from end to end of the network.

Alternatively, abs module could be damaged and not forming proper packets.
This doesn't seem plausible for multiple reasons: I have tried 4 different ABS modules and all act identical. Additionally all other sensor reporting of the abs system seems to be working properly, justified by a working speedometer.


The ECM could be damaged and not reading the packets properly. If this was the case then I would have a lot of other problems on my hands. Also, I have replaced the ECM with a known working module and wiped the codes and the P1637 code came back when the key was inserted into the ignition.


Once I get my can bus sniffer, realistically we are either going to notice that the packet is there reliably, or intermittently. I am not certain that observing either will really definitively tell us what is going on. Unless all of the known working replacement modules that we tested in the car are all bad in the same way when inserted into my car, and then work perfectly fine outside of my car. Something else, environmental, has to be interfering with this specific message being sent across the network?


Do these can bus modules sign their packets with a security checksum? Could it be that the software has been updated on the modules in the car and I don't have the correct software on these abs modules i am trying to install? I suspect it is something along these lines?

 

All four of the active modules (INST, ECM, TCM, ABS) send a token that is sent repeatedly and is essentially the 'heartbeat' of the modules. They are all received by each other and by the network monitor. In your case, it's the result of the ABS CAN token not being received, either because it wasn't sent, or the receiver did not recognize or receive it. So, if ABS is not sending it over the bus, and the bus has continuity, it is the ABS. If the token continues and is seen on the network, then it is some issue with the ECM. Perhaps if the bus is very noisy, it's the bus. Keep in mind, your previous measurements are static. It is possible for the bus to be too noisy, but I have been amazed how robust the bus is in the presence of noise. So, probably not that?

In your case, since it happens immediately, it should be very clear what is happening (e.g. the ABS token is never sent is one possibility), not some intermittent error that only happens once a month. This is my case where the ECM randomly turned off for about 3 seconds during a month of driving, hard to catch, which is why I did all of this. Finally, I caught it happening a while back.

And yes, there is a checksum on all of the CAN messages.

But taking a step back, are all of the modules you have installed the correct module for the car? That is, the VCATS number is the same as yours?

In any case, for reference, here's the thread with my basic attempt to decode all of the messages from the XK8-2001 CAN. Should be very similar to yours, and the ABS heartbeat token should be the same, I think.

https://www.jaguarforums.com/forum/x...-sc-so-222041/

 

Here is my VCATS label




ECM




TCM



ABS




ABS PUMP







My VCATS label is relatively useless to discover whether or not I have the correct modules installed on the car.

I just went into the engine bay while I was taking these pictures and checked the CAN BUS connectivity between the ABS -> TCM and TCM -> ECM and everything looked good, again.


Am I correct in believing that the vehicle speed information comes purely from the ABS module, and that the speedo would not work without ABS can bus connectivity? Bizarre that I have a working speedometer, but an error indicating that the abs heartbeat is failing, if that is the case.

 

Okay, but all of the modules at least have the same part number, if not the VCATS revision? There was an interesting posting on your ABS part number a while back by motorcarman (#2 in the thread below) discussing the part number your have on your car for the ABS module

https://www.jaguarforums.com/forum/x...2210ah-184883/

As for the system, ff a given token is lost, the other modules have default settings/behavior they adopt so that the system 'gracefully fails'. So, I don't know if speedo would fail to do something, it could depending on what's happening.

By the way, are you hard resetting the system every time you change modules (battery terminals negative removed, touch on positive for a few seconds) and resetting the code?

 

I am working with someone who rebuilds these ABS Modules.

The ABS module that came on the car appeared to be the incorrect model #.
It took me some time to get the repair company to send me a test module of the correct model #, he kept sending me other modules that he said "should work" with my car.

All in all, I have tested all of the modules that had ABS and TRAC, and I believe I have the model number installed in the car currently that the car was supposed to have in it originally.


I am removing the positive cable and touching that to the negative for minutes to hours between each time I work on anything electrical. Have had a bad experience with starting a fire when I didn't remove a battery lead and something randomly shorted.

 

@crbass Maybe you could give me some help with this as you are far more knowledgeable than I am on this.

I pasted the first 500 lines of my log here: https://pastebin.com/QXa90N4q

This is the log of the car with the key in the on position, but motor off.


The duration of the whole log is 30.5s.

The heartbeat messages were as follows:

ECM
Found 152 messages
Message structured as: 7d0 Rx d 1 14


TCM
Found 141 messages
Message structured as: 7d1 Rx d 1 14


INST
Found 154 messages
Message structured as: 7d2 Rx d 1 14


ABS
Found 245 messages
Message structured as: 7d3 Rx d 1 c4


Considering how the data being sent by the ECM, TCM, and INST are all "14", and the ABS module is sending the data "c4" for its heartbeat, I feel as though I may be dealing with a software incompatibility problem here?

Am I on the right track? I think I have stretched my limits of understanding the can bus data log that I have captured. I am just reaching at the moment.

The amount of heartbeat messages that the ABS module sent out was significantly higher than the other modules as well.

 

This could be your problem, hex 14 is your model number and revision. Hex 14 = binary 10100 - Jaguar Xk8 (leading 1), rest is revision (X100). Hex c4 = binary 11000100, not sure what the network monitor or the other modules do with that, but perhaps don't see that as a valid token, hence P1637.

Two of three of the 'regular' ABS CAN IDs show up in your stream. Not 0x480h (i.e. 480), which is the speed sensors, but the motor is not on. And the tokens appear to show up as often as needed so that the car doesn't think any of the the modules are off.

For grins, I'd check to see if you get ABS ID 0x480h when the motor is on,

I attach your data filtered with just the module tokens and ABS messages that I put into excel just to make it easier for me to filter individual messages.

Fix? My opinion, either replace with one that sends the correct token or reprogram ABS module, if that's possible. On reprogramming, I think there is an option in IDS for this, but it is not at all clear it will fix your problem, seems like it's just a procedure to reset the ABS parameters. It appears there have been many, many replacements of the ABS without any programming as long as the module was the correct part number. If it was me, I'd worry that the module is either fundamentally incompatible or fundamentally corrupted. I'd replace.

 

Just to add that the parts catalog (from this forum) shows only two abs module options for that car:-

JLM20129 without traction control
JLM20130 with traction control

you need to cross reference those part numbers with what you have in the car.

 

For programming, there is the thread below which both outlines the modules for various models (same information as dibbit above, just for more models), but seems to indicate that for brand new modules there may be some programming needed, for the proper used modules, not needed. Perhaps this means that programming as a new module (using IDS) is an option, however, if you have the right part.

https://www.jaguarforums.com/forum/x...y-x308-126341/

The unfortunate part about this thread is that the programming procedure is not outlined, but may simply be the new module procedure for ABS in IDS. If you have access to something with SDD/IDS, it hardly seems like a risk to try it.

But thinking outside the box (thinking about this too much today), it may be that all you need is that token correctly sent. A 'clever' solution is just to permanently attach wireshark to the OBD port and send the correct token periodically. I'd bet it would ignore the other 'bad' one since it may be ignoring it now. How clever this is depends on 1. whether it works, 2. whether the ABS is working properly apart from this, and 3. whether you can just get a relatively cheap replacement. If 3, ignore all of the above.

 

@crbass Thanks for the additional knowledge added to the conversation. I agree and I suspect that they are checking that model and revision to see if it is the correct part in the car. This P1637 being the erroneous error being thrown instead of incorrect part fitted.

@dibbit Yessir, I had previously taken that information, added on that my car came with traction control, contacted a dealer to get the information of what module part # came on my car and that is what is installed in the vehicle at the present.

While we are speaking about module part #'s I have two different versions of this abs module sitting here in the garage. The one that the dealer claims should be on my car, and the one that came on the car when i got it ( used so unknown history ).

The model # of the part that the dealer claimed should be on my car: LJA2210AH
The model # of the part that the car came with when i bought it used: LNC2210AD

 

So, you currently have two modules, which one is on the car now? And have you attached the other module to the car (perhaps without removing the first one) and seen if the behavior changes? Since you don't need ABS and you may be able to do this without removing the module or moving the car, it seems like it might take minutes to check.

 

@crbass Was getting ready to go swap them out and take another can bus log and compare them.

I also had thought about creating a CAN transmitter to send that hearbeat token and call it a day, but I want to fix this right, and the OBD2 port has to be open for the smog testing it needs to do ASAP. I think that is a viable way to solve the problem if i build one inline, but not the correct solution to the problem.


I also just called the local jag repair shop that has IDS and he basically told me to stop talking to him because he was too busy, and that the car was unable to be repaired and that I should take i should just tow it to the junkyard.

Now I have to go call around and find someone that has IDS that wants to repair cars and make money, instead of severely insulting their clientele.

I guess I also have to go find a shop willing to do the other work I was going to have them to do my XJ6 as well.

 

Hmmm. Wonder who peed in his cornflakes today?

 

He was screaming about how no one would ever try to "put their neck in a noose" in regards to offering to program a module for a customer with IDS. And good luck finding anyone in this area with IDS because they were the only ones with it.
Also screaming about how can bus was magic and the car wasn't worth him spending months on it to try and diagnose it. blah blah blah.

Not the kind of person I would want touching any of those magical electrical noodles in any car of mine for sure, in fear I might burn to the ground.

 

Good lord.

 

Just went and plugged in the other ABS module into the car and did the same engine off log that i did before.

First 500 lines are here: https://pastebin.com/zMLsh3KP

The ABS heartbeat still reporting c4.

 

Well that's both encouraging and discouraging. Encouraging that it seems that that is likely your problem since both are doing this. Discouraging that you have no module reporting 14 instead of c4.