+! replace battery. 12.14V is too low. At some point below 11V while in start position the ECU will not provide ignition, and I expect that's what occurred. All those codes are a symptom of low voltage, also.

 

I replaced the battery this morning. Just for grins, I measured the resting voltage of the old battery before removing it. It measured 12.24v at rest and 11.83v when I put the ignition in Position II and turned on the headlights.


The new battery at rest measured 12.46 volts and 11.95 with the ignition in Position II and the headlights on. Not a remarkable difference.


The voltage measured at the new battery when the engine is running is 14.18v, so the alternator appears to be working. The new battery was manufactured in January of 2015 so had some shelf time and may improve a bit once the car has a chance to charge it to its maximum.


So now, I will drive the XJR to see what happens. Most likely there is more of a difference between the old and new batteries than just voltage.


I will keep the forum posted. Thanks for all your input.

 

Did you charge the new one for 12+ hours first? They usually come part charged only.

 

No, I didn't. The seller said that it wasn't necessary, but to be sure, I will pop it on one.

 

You did not say that the codes came before you tried to crank, but you implied they did not, meaning your battery might just be the culprit. And the leaving the cables connected for a time is also a red herring (but who knows!). I don't know what the dual switch connection is with the issue at hand, but it has been reported to be the magic elixer, so I suppose it would be worth trying.

BTW, a poor, but better than nothing, way to test the battery under load is to turn on the headlights and watch them or the cabin light for dimming as you crank. Get used to "normal" and you will spot a difference as the battery is failing.

I suspect you are either going to have to get the equipment to diagnose the CAN bus (a scope would be a good start) or begin changing CAN bus components. I assume you have inspected and cleaned all of the CAN connectors by now, right?

 

The instrument pack messages appeared before a crank was attempted.
I was waiting for the System Check to complete and then received the messages:

• ASC Not Available
• Trac Not Available
• Engine Failure
• Wrong Part Fitted, and
• The Climate Control beeped at me 6 times, I think it was 6, and displayed 'Err'.

Once the messages above were displayed, the car was a brick. It would not crank.

The P1797 codes were read after the hard reset. I was not able to establish communication with the ECM for OBDII codes after the instrument pack messages were displayed. I was able to read the P1797 code after the hard reset.

I have cleaned all the CAN Bus connectors and checked for bent pins and sprung/distorted pin sockets and performed the Jaguar Service Training CAN Network Integrity Check without WDS. The readings on my CAN Network are reasonably close to those documented in that article.

I do have a spare BPM and TCM that have the same VCATS number as what is installed, but have not made that leap as of yet. For instance, if the spare TCM that I have has the exact same VCATS number, is it an exact swap. Is voodoo or reprogramming required?

Also, I would not know how to analyze the CAN with a scope. Can you point me to that procedure?

Thanks for your input.

 

I am pretty sure the TCM does not need a configuration. The BPM will be a different story due to it's mileage integrity functions, but I think there is a pretty simple way to get it up to speed enough to test with it. Look for archives from motorcarman and other Jag techs.

There are at least three ways to see what the CAN bus is doing. High end auto scopes like my Picoscope 5000 can decode most of the CAN protocols in a sniff kind of mode. I have not actually used it on any of my Jags yet, though, but I assume it can decode the protocol Jag uses.

Another way with a general purpose memory scope would be to look at the waveforms of the bus traffic and notice if any signals look "defective". Since your problem is somewhat intermittent, it might be that you will spot packets from a deteriorating module, then disconnect modules until you ID the offending one.

Probably the easiest way to find the problem would be to use on of the dealer level scanners to read CAN bus errors from each of the modules and determine a pattern from that. While the bus is faulted, attempting to connect with each module would probably give a good indication of what is happening. One thing a scope and a scanner will determine is if the whole bus has gone haywire or if it is just a single module. AutoEnginuity with Jag extensions will set you back about $600. and will read the CAN bus errors. Better would probably be the IDS software with a Mongoose interface module- I don't know the cheapest / best way to get into that right now, but I suspect it will cost about the same as AE. Look to the archives for dealer level software.

Good luck. And keep us posted.

 

It has been almost 9 days since I replaced the battery in my XJR. I am not ready to declare victory, but the no-crank issue has not reoccurred since the battery replacement. Yay!


If replacing the battery is the final fix, all the other effort was not in vain. All my grounds and positive cable termination points are now clean. The CAN Bus connectors are all clean and I have learned a ton about the XJR and where everything is located. The XJR is a bit less mysterious now.


I will cautiously continue to drive the XJR and report back to the forum.


Thanks.

 

It has been two and two third weeks since I replaced the battery. All has been good until this morning. After cranking normally, starting and a very short drive to the bank (< .5 mile), the car would not crank on the first attempt. It showed the usual messages (ASC Not Avail, TRAC Not Avail, Engine Fail, etc). This time, the Climate Control did not beep and give an error.


In the time it took me to get my 10mm wrench and prepare for a hard reset, I tried to start the car one more time. It cranked and fired right up and left me a nifty check engine light. I am sure it is the P1797 code, but I have not checked it just yet.


So, my next step is to continue driving it. I can always do a hard reset if I have to, and to either have my local Indy see if he can read any error codes from the CAN Bus modules or put that money toward my own scanner that can do the same.


Was there ever a consensus in the forum as to which scanner is the best for a X308 owner to buy? Autoenginuity? Other?


Thanks for your input.

 

I think i got the same code on my 98Xjr the cause was a bad transmission plug adapter. Super common for them to leak internally on the 722.6 and throw codes. Very easy fix, very cheap part. I reset my trans codes a few time before they stayed, replaced the connector (that was definitely leaking internally) all became well. I believe bad conductor plates (also very common for the 722.6) can cause the same code.

 

MVirgil: Thanks for the information. Can you tell me what the 'conductor plates' are that you refer to on the 722.6?




Thanks.

 

Cyberg,

When i responded to your post it was way past my bed time. I re-read through it tonight and i don't think my suggestion of trans electronics is correct. I have had communication error codes, but i was pulling the codes directly off the trans not from gen OBD2 (i have a scanner with access).

Below is the reply to your question.

The conductor plate is the PCM board mounted to the bottom of the transmission valve body. Typically conductor plates throw input and output speed sensor codes but i have read of a failure causing communication issues as well. i would think a leaking adapter plug could be a more likely culprit. In Mercedes the plug will leak and fluid will wick up the wires and fry the TCM (i dont know if it can get to the TCM in a jaguar but i do know the connector leaking internally will throw codes from first hand experience). Another code you mentioned of info makes me suspect something with the trans electronics is the "part not recognized" code. I read about something similar on a different forum when a jaguar owner some how had the wrong 722.6 installed when he orded a re-man trans. Our cars have a 722.650 and he put in a 722.605. on attempted start up "transmission not recognized" was the fault code. I hypothesize corrupted communication between the TCM and transmission could cause the transmission not to be recognized. Again the adapter plug and transmission conductor plate are very common issues on the 722.6. You can see if the plug is any good by unplugging the wires at the adapter if they have fluid on them then the plug has gone bad. On our cars there is a heat shield that must be unbolted and i found removing the cat to transmission bracket helps gain access.

Conductor plate:
00 2000 Mercedes E55 AMG Automatic Transmission Conductor Plate - Transmission - Beck Arnley, Original Equipment - PartsGeek
Plug:
00 2000 Mercedes E55 AMG Automatic Transmission Plug Adapter - Transmission - APA/URO Parts, Beck Arnley, Dorman, Original Equipment, Replacement - PartsGeek

MB forum 722.6 FAQ
Mercedes-Benz 722.6 Transmission FAQ - Mercedes-Benz Forum

 

Thanks for the detailed information. It definitely furthers my education.
When you had the xmission fluid leak into the interface cable socket, did your car not crank at times or did it just throw error codes?

 

just error codes and odd shifting.

 

Thanks for the clarification. I will definitely add checking the transmission pin connector for leakage to my list.

 

I want to specifically thank BlackX300VDP for his post alerting me to his experience with a failing diode in the Engine Compartment Fuse box. That tip altered my thinking a bit and led to the following discovery.
Pulling the Ignition Positive Relay (Gnd provided thru the diode) located in the Engine Compartment Fuse Box causes:

• ASC Not Avail
• Trac Not Avail
• Brake Fluid Low

This is the error condition remembered by BlackX300VDP.
** Pulling the EMS Relay (Gnd provided thru a diode by the ECM) located in the Engine Management Fuse Box duplicates the error! **
I replaced the Engine Management Fuse Box with a used one acquired from eBAY. I tested the diode on it before installing. The old fuse box tested the same as its replacement. But I replaced it anyway.
After replacing the Engine Manage Fuse Box all was well for about 5 days then the problem returned. When the No-Crank occurred, I noticed that the EMS Relay had not tripped. Lightly thumping the relay would cause it to trip. I replaced the relay with another one that I had and it behaved in the same way. It would trip most of the time but when it failed, it would trip when thumped. This may indicate that the ground provided by the ECM was not sufficient to provide enough voltage to trip the relays.
Tutorial - The EMS relay controls a second +12v bus in the Engine Management Fuse Box that provides voltages to:

• Additional ports on the ECM
• EGR
• MAF
• Throttle Motor Power Relay
• Ignition Coil Relay
• O2 Sensor Heaters Relay
• Etc.

So, based on the above, it is easy to see why a problem is caused when the EMS Relay does not trip.
Possible causes are:

• Flakey relays
• Bad wire providing ground from ECM to Engine Management Fuse Box Fuse box
• Bad connection at ECM
• Bad connection at Engine Management Fuse Box
• Flakey ECM

So, I verified continuity of the wire that runs from the Engine Management Fuse Box connector (EM20-6) and the ECM connector (EM81-03). The wire from pin to pin had continuity. I wiggled and shook the wiring within the ECM enclosure and at the Engine Management Fuse Box. Continuity was maintained. I visually inspected the EM20-6 female connection used by the ECM. It appeared to be lined up just like its siblings, not bent and was shiny. I gave it a shot of electronic contact cleaner just for good measure.
I then cleaned the Engine Management Fuse Box pins with a dental scaler until they were reasonably shiny and cleaned them with electronic contact cleaner. I also replaced the relay with a younger one that I had. I plan to purchase a new relay and put it into service in its place.
So far, the car has cranked each time for the past 24 hours. The time is too short to prove a fix and it has done this before.
If the problem reoccurs, my next step will be to splice another wire from the ECM to the Engine Management Fuse Box to eliminate any continuity issues with that one wire. If that effort does not fix the problem, then I will suspect the ECM and have it checked out by one of the rebuilders.

 

I am happy to help when I can. It's been many years since I've thought about those no start issues. I'm glad that you have the wherewithal and energy to chase after the issue. I remembered a little what we were doing at my dealer during the stalling concerns before the throttle body recall came out. We were replacing the EMS relay and engine controlled relay (I believe you have them pinpointed). There were date codes on the relay boxes that alerted us to inferior parts and to replace them. Even if it had an acceptable date code, we would replace them. Relays were always a little shoddy. There is a bulletin for this on early cars (AJ26) that we used as a guideline for later cars that exhibited similar concerns. We also replaced the fuel pump relay at that time. In addition, we were told to check as many grounds as we could. This sometimes included removing the radio and there was a big ground under it that had a number of wires attached. We went over the positive feeds as well. The bulkhead junction being the biggest contributor of no starts. The X100 cars had a positive feed going through the body at the trans tunnel and would produce no starts as well.

I am amazed at all the work and specific information you have learned from this adventure.

The original wiring diagrams, as the story goes, were printed up and a fellow in the UK would go after every circuit to see what that circuit did. The diagram included an active and inactive bit of information. These were incredible to use since sometimes you didn't have the same car to compare to in the shop. I hope you have been able to use that information for you car. It is invaluable.

I'm sorry I haven't been on here as much to check progress. I'm at BMW now and working harder for less money. HAHAHA. I still have a strong passion for Jaguars and help when I can. Thanks!

 

I think I am nearing the end of my problem. At least I hope that.


I am replacing the EMS controlled Relay located in the Engine Management Fuse Box and the Ignition Positive Relay located in the Engine Compartment Fuse Box with new OEM Jaguar relays. I hope that they are not a part of the flakey batch that BlackX300VPD talks about.


Inline with the experience of BlackX300VPD, I will also be replacing both fuel pump relays with new OEM Jaguar relays. I know that those two relays are not a part of this problem but replacement is a good preventative measure, because it is likely that most of the relays in my XJR are the original factory installed units.


BlackX300VDP:
You talked about wiring diagrams that you used at the Jag dealer that had been marked up (active and inactive bits of info) by a chap in the UK. I don't have that version and used the non marked-up wiring diagram provided on this site. Can you direct me on how to get the marked-up version? Any additional notes concerning wiring circuits and just what they do and impact would be a great asset now and for the problems that are sure to come in the future.


I will be installing the new OEM relays later this week after they arrive. I am not ready to declare this problem corrected, but through all the aggravation, mystery, despair and study I find myself no longer intimidated by my XJR. Much of the mystery is now dissolved and at the end of the day, it is just a car; a machine to be dealt with.


I still have a healthy respect/fear of the computer modules. Anything with software logic can be a pain and a mystery at times and will make repairs more intricate.


I will keep the forum updated and hopefully we can all rejoice when this problem is resolved, because I will not be the only one to experience it. Guaranteed.

 

I had replaced the Engine Management Fuse Box with a used one acquired from eBay prior to discovering that pulling the EMS relay would duplicate my problem. All was good at first then the XJR just stopped running twice while driving. It had not done that before, but had stopped idling in the driveway once prior to replacing the fuse box. Having the car shut down while driving is not a fun experience.

Each time the car shut down, I turned off the ignition, then put the ignition in Position II and then tapped on the EMS Relay. The Relay would click and the XJR would then crank and start.

My problem is probably not a relay issue. It is a fuse box or connection issue:

• Flakey diode connection to the EMS Relay
• Hairline cracks in the fuse box PC board
• Loose/sprung relay connectors on the fuse box
• Old solder joints in the fuse box

Continuity to the ECM has been checked and is good. If the ECM was failing to provide ground to the EMS Relay, then tapping the relay would not cause it to trip.

I have decided that enough is enough! I is time for a NEW Engine Management Fuse Box. I ordered a new Engine Management Fuse Box from SNG Barratt for $135. This new box will eliminate failures due to:

• Faulty Diode feed to the EMS Relay
• Possible loose/sprung connectors at the EMS Relay
• Time and heat weakened solder joints
• Hairline cracks in the PC board within the fuse box

I am returning the eBay acquired fuse box and have reinstalled my original while waiting for its replacement to arrive. I will also be using NEW OEM relays for the EMS relay and the Ignition + relay to eliminate another known variable.

I will keep the forum updated.

 

Did changing the fuse box help? I have a xj8 with the same problem. I also get code u 2500 out of abs module. The fuse box you are talying about is that the small one with the one relay?