Doesn't it all point to an ECM related problem? It was replaced, messed about with, the dealer had problems programming it and the technicians will hardly be familiar with the car and its idiosyncrasies. I assume the thing about needing the old one to program the new one was because they needed the old firmware to load onto the new one but if the new one was slightly different in hardware terms whose to say the firmware would actually work reliably? Well, Jaguar of course but it's what 20+ years old technology? They probably lost the guys who really knew it years ago.

As a side question the control units are Jaguar made not subbed out to Lucas I assume? I ask as I know a guy who was very technical and senior in Lucas 20+ years ago and has a long memory.

 

Thanks for the heads up, Michael.

I think I have repaired the links - please see if they work now.

Cheers,

Don

 

Call me dumb,,, others have and for good reason, BUT,,,
Is this info and are these files available, somewhere?
And if so, would/could you link me to it?
​​​​​​

 

Thanks, Don - yes they do now.
Should X105 read X103 or have I missed something on the model # increments?

@Jay - Use Don's links or they're both in the relevant forum stickies:- this one and X350/X358

 

Thanks, Michael. I fixed that too. That's what I get for trying to post quickly during my lunch break!

 

What happens if the engine starts and the alternator fails immediately and voltage drops under 12v say? A friend suggested that if that happened when the engine starts the ECU might think the engine didn't start and shut everything down - a bit fuzzy but could it?

 

See! Dumb!
Thank you, Mike...

My experience with alternators is that if there is a failure or some kind of catastrophic alt failure mid drive, the car will continue to run on the battery power,,, until the battery no longer has the power to support the cars systems. I've never had a car that just died or shut itself down due to an alternator failure... But again, MeDumb,,, lol. And ain't afraid to admit it 😂

 

LOL - I doubt it. More likely somewhat scatterbrained, which I can totally identify with

Doc, the modules are all Denso and, IMO, nicely engineered. A car isn't the friendliest environment for any electronic stuff.

I've been pondering (invariably dangerous) about the ECM relay mentioned by Don (in our cars, the one in the engine management fusebox). The ECM controls some of the power to itself (to allow certain actions after ignition switch off), and also to some of the engine management electrickery. This is how it is able to shut things down - for example, the injectors - when the inertia switch trips.

 

So it's completely possible that the ECM shuts its own power off after 2 seconds.

Does anyone know how frequently it polls the inertia switches for example. I'd assume (as an example) it wouldn't look at the inertia switches as a priority at start or while stationary but might do so by defaults every so often moving or not.

What might the ECM look at that could cause a shut down?

Personally I think the fact that it's a new ECM with old software could be a root cause. I have no idea what can be done about this but I have enough experience of computers to know that subtle hardware differences can play merry hell with software even though 'they shouldn't'. I recall the server that would reboot when you copied a large file - there was no way you'd expect this and that server controlled a steel mill. I wasn't terribly popular that day. They might have mentioned it.

 

My musing again, but it's possible. The delayed action after start makes sense as it gives time for everything to settle down after startup. (P035x codes, for instance, aren't thrown immediately after startup if there's an issue with the coil/feedback circuits).

It's a grounding signal from the inertia switch, so my guess is that will raise a processor interrupt rather than being polled, since an immediate response is required.

I can't think of any reason why you'd want the motor to shut down immediately other than if the car thinks it's involved in an accident. Certainly wouldn't want that on a busy motorway...

Could still be an ECM issue, I suppose. Module config got a lot more involved for the 4.2. Have a look at the two posts from motorcarman here:
https://www.jaguarforums.com/forum/x...5/#post2495007


P.S. Don't ya' just love computers? Your story reminds me of an 'incident' in my younger days when using an early incarnation of MS software. I managed to copy the contents of a blank table over a populated one rather than the other way round. Happy days...

 

Hmm, just read that VID stuff from the link and I'm assuming the Jaguar tech guys wanted to read the configuration stuff from the old ECM rather than as I thought the firmware which it seems will be taken from a library of possibilities based on the VIN number.

I can't recall if we were told but is the new ECM the same code number as the old one? It must be or the Jaguar techs would have mentioned it. Using the word superseded would imply to me that if X supersedes Y then you can use X in place of Y and lose no functionality but I wonder if that's what was really meant in this context?

It also sounds fairly straightforward and non-destructive if stuff goes wrong in the various transfers.

I take your point about an interrupt rather than a poll - I think a little bit of CANBUS trawling is required, are there any messages that request an immediate shutdown? I guess there will be. There's some guy on the forum who knows a lot about CANBUS and wanted to hack it, I wonder if he is reading?

I was somewhat surprised to read that the display control module was a repository of data that other modules referred to. Also talk of weak batteries.

Where do you guys get all this deep technical knowledge?

 

Well the jag technicians do a 4 year apprenticeship taking government set exams and also attend the Jaguar training school for specific courses and when new models come out.

 

i’ve heard x103 won’t transfer immo id unless you use a virgin ecm. if that’s the case i guess grab a ktm from the same donor car

if it was immobilized it would have a starter inhibit and a p1260

 

daro31,

I found an even more detailed summary of P1611 in an AJ27 DTC Summaries manual which may also be applicable to the AJ33:




Also, you might want to read the training manual section on the Denso 32-bit Engine Management System in the EMS training manual at this link (thanks to motorcarman and Gus):

Jaguar Engine Management Systems and Advanced EMS Diagnostics - Book B

Cheers,

Don

 

I'm looking at two drives cycles with roughly a second each which makes 2 seconds. In both cases there is a reference to throttle motor - so what happens if the software senses a failure there? It can't be good but it wouldn't actually stop the engine of itself but the ECM might say hold on boys this engine's not going anywhere?

From an earlier document there was some rule about checking communications between modules and data errors. If the data between modules was found to be corrupt it would request 4 tries to get good data with about half a second between each cycle. It wasn't clear what would happen if that failed but it can't be good if for example the temperature control module fails that test or teh security fails the test. If the car knows it's not moving it can also work out it can safely stop the engine.

The more I look the more I realise the car runs on software.

 

The 2 drive cycles means the MIL won't come on the first time this happens, it only comes on the second time - in other words its the warning light, not the fault.

We are certainly all learning an awful lot about this fault - I wonder if the OP is still here?

 

Thank you.

Well I'm certainly learning a lot. You definitely don't want corroded pins in any of the modules or other connectors although the CAN bus seems quite a robust system in terms of managing data failures.

 

Thanks, Don.

The EMS diagnostics document makes it clear that the engine shutoff on high temps is the V6 as there are extra sensors (cyl. head temp), so that rules it out here.

 

THe car can be immediately restarted for 2 second time and time again.

 

hook up a pressure gauge. sounds like the fuel pump driver is authorized to prime and then never turned back on when it cranks