The DTCs beginning with a 'U' are typically communications issues between the various control units. Remember to use the Jaguar specific list of DTCs for the correct description of the faults and causes.

Has the battery been tested with a voltmeter for providing the correct voltage?

 

I did check the battery, it was 12.35. I did put a charger on it. I just checked again after driving in to town and it’s 12.55

 

The battery is marginal.

Next step is to check the wiring looms and perform a check of the CAN system. Was the vehicle ever in an accident or flooded?

 

I’m going to check connections. No accidents or floods.

Is the can check done with software? I am waiting on that from the uk.

 

Start with a visual inspection of the connections to make sure they're secure and there's no damage to the wiring looms.

 

10-4. We did check and clean the connection on the back of the transmission. It looked like there was a little tension on them/ they were twisted.

 

Brad,

I have attached a print out of the Jag manual DTC summaries for some of these codes. I ignored a few of them because they don't seem related at all. (These cars store codes for weird things all the time. If you obsess about every one of them you will lose your mind)
There seem to be 2 things going on. the U2521 is about CAN communication with the DSCM (Dynamic Stability Control Module). This wouldn't seem related to shifting issues so I would put it aside for the moment.
The other codes I circled on the attachment are all (possibly) related to TCM CAN errors. THIS is similar to what my car is showing when it blows a shift. My suggestion would be to clear all the codes and go cause a few missed shifts or gear blowouts. Then read the codes again right away so you can narrow down only the codes associated with the shifting problems. If it continues to show CAN to TCM errors it must be a failed TCM, ECM or the CAN wire between them. It's also important to note that neither of us has ANY transmission error codes. The TCM thinks everything is fine but the OTHER modules are showing communication failures with the TCM. My working theory at the moment is that the TCM has a hard internal failure, looses control of the valve body momentarily and then resets itself and gets back on track. While all that is happening it stops communicating with the other modules and they throw CAN codes. The only way to test my theory is to swap out the TCM with a good one and see -- which I will be doing to my car shortly.

What I wouldn't give to spend a few minutes talking with one of the people who developed this system.

Jeff

 

Thanks Jeff,

Have you tried manually shifting in to second, so it’s locked in gear and not trying to shift, then accelerate hard? I only ask because that’s how I got it to throw the p1643. I’d be curious to know if that does anything. When I do that it immediately goes in to restricted performance/trans fault.

 

Brad,

I thought you said this happened in 3rd, not 2nd... I will try both when I have a chance. The speeds involved are quite high so I need a long stretch of quiet highway with no troopers which is extremely rare around here. If you have it in 3rd and you are below 50 mph (or so) it's going to try and grab 2nd if you floor it. If you keep going, 3rd will come up at about 68, and then 3rd will take you to 105. It's really not easy to test.

Jeff

 

You’re right, I did both. Today was 2nd at about 50-55. No shift attempt by the car. It went to limp mode almost immediately.

 

Check your CAN, ISO and SCP buses for shorts. I do not have this problem with my car however many others. I have multiple bus shorts to B+ and ground. These cause missed messages etc. Also prevent proper programming of modules.
If you do not get a proper communication when you accelerate it will drop into default mode until you get a proper message transferred. The change back and forth may cause your symptoms.
The car will run with many shorts, but not program, and will give odd, seemingly unrelated, faults.

 

Thanks OldKarz,

Before I start ripping in to the interior and chasing connections, I plan on dropping the valve body and renewing seals/bridge seal. Mainly to make sure they’re good.

I’m betting (based on others input) that there is a hard fault in the TCM. I’m going to send it off to these guys http://g7computers.com/. They have great reviews and don’t charge if they don’t find a problem. I did find a cheaper alternative but they’re reviews were terrible.

I am also waiting on British diagnostics so I can do the adaptation clearing, reset codes etc.

Based on the forum and Facebook group I may as well keep the diagnostic computer in the trunk!

I’ll update when I do these things.

 

For the basic tests, you do not need to take anything apart. It can be done from the OBD connector. From there you can tell if your buses are terminated correctly and continuous. Also it will show shorts to ground and B+. Also shows if the signal is riding at the correct voltage level.

 

That is good to know! Is it done with the IDS/SSD software?

 

That is why I made my own setup with IDS/SDD. The Computer repairs to diagnose first that my ECM was defective was $149 at the dealer, after I had already narrowed it down to the ECM in the first place using normal troubleshooting. Then after the dealer verified a defective ECM they had no option but a Jaguar solution that was no longer available without some very high cost in the Thousands of $$$$.
After some searching and calls I found Foreign Auto Computer Repair Inc. and for $250 they quick turnaround repaired or replaced the ECM or TCM including transferring the security / key and warranted it for 5 years. It was literally Plug-n-play. My local JLR service manager asked me for their information and they use them now for older vehicles where JLR no longer supports parts.

So for a little more than that amount of diag and repair investment, I now have IDS/SDD and can do it myself so I can pinpoint test and verify.

 

The tests are done with a DVOM and you can follow the pinpoint tests in the workshop manual. They are all in the network testing section for each of the buses. It can be hard to get the DVOM clipped on to the appropriate pins so I made an extender with much larger connections for the DVOM clips. It was worth the effort.

 

In my case SDD could lead one astray. It showed ECM Com faults from a number of modules. I figured the ECM needed replacing. However when I tested further. Using the DVOM and OBD connector my resistance to ground and also B+ was 5k Ohms. The minimum should be 10k. I believe an actual good system will show 400k+. The easiest module to disconnect and test is the DSCM/ABS. It showed 16k to each of ground and B+ on the module pins. Each was a separate path so the bus resistance was 32k. There are two shorts in that module. Next in line measured from the DSCM/ABS connector's pins have the TCM and ECU in parallel. The resistance was 8k. So there was another short in one or more of those. Going further it turned out there were 2 11k shorts in the TCM. The ECU did not have any shorts! However every time the ECU was connected the resistance would drop from 22k to 8k, The CAN is terminated in the ECU with a 120 ohm resistor across CAN+ and CAN-. Being in parallel with the TCM and DSCM/ABS this joined the shorts in the other modules. The result gave the 5k Ohms.
I do not think there is anything wrong with the ECU however cannot update/program it with SDD due to the other shorts. Jaguar points this out in their manual that the buses can make the car run with many bus problems. However they say programming will not be possible or faults will occur. That is how I got into my mess to begin with. I did not check the buses before programming!

 

I’m going to need more wine and to reread that a few more times!

I hope I don’t have to get in that deep!

We did drop the valve body today. As I expected the bridge seal was fine. Nothing looked obvious. Mechatronic is on its way to get checked. I didn’t want to spend more money but I went ahead and ordered the solenoids and zip kit. My money is on the mechatronic after talking to Jeff and reading other threads.

On another note there is a power steering drip at the clamp on the pump.

trans lines have hose clamps around the metal to rubber connection.

On a positive note i discovered that the head rest is electric which made me chuckle. Oh! My grease gun hose was leaking and I happened to have one laying around...so I did fix/accomplish **something** today 😂

 

So a little update and more confusion. I’ve been blowing up JCalhoun’s inbox daily.

We have gone through the valve body, seals, etc. Double checked fluid, re gapped spark plugs (they’re fairly new and the factory gap was larger than spec). The only thing I haven’t done is coils, none were oil soaked.

There are no codes in the TCM, we reset adaptations and did the drives.

We did some data logging of the solenoids. The input output speed sensor values drop out.

Here are some video links to this angry cats behavior. Ignore the air fault, I swapped a strut while it was in the air (right front was leaking down) and it never cane up. Compressor sounds weak, that’s next.

 

Brad, i purchased a 2005 xjr back in Sept. with about the same mileage. Overall a great car. I'll be following your post and hope its something small.

It's a long shot... i realize they are sealed, but has anyone checked the transmission fluid level? I have a Dodge diesel truck and low fluid can cause all sorts of shifting issues. Usually a shop can verify the correct level.