I would expect a re-flash of the TCM to replace the firmware. So it not only clears the adaptions in volatile working memory, it also replaces the software image and any standard map files in the permanent flash memory. It's like reinstalling the OS on your computer. But the TCM only has 440kB of flash memory, so it should only take a few minutes.

Disconnecting the battery or pulling the TCM fuse will clear volatile memory, but it won't help with anything related to the software or maps in flash.

 

I've heard that disconnecting the battery does not clear the TCM adaptations.

 

Since the TCM is built by ZF, it may have a different approach to storing working parameters than the Jag modules, i.e it may well store those in flash too:

I took the 'vehicle-specific' data to be model-related maps, but it could also be adaptations specific to the individual car.

 

Fair point and good find - the term "flash memory" would imply non-volatile memory so not likely to be cleared by removing power.

I'm starting to feel like finding a ZF specialist or authorised service center and getting them to take a look at it, not sure I trust my local Jag dealer...

 

That doesn't mean it doesn't have normal RAM as well - it has to, in order to be able to do working calculations; flash is too slow. The question is: where does it store adaptations, i.e. changes to standard parameters due to individual gearbox characteristics, individual engine power & torque characteristics and (possibly) driving style? I dunno...

 

Had my car out for a drive on Saturday morning, it was fine until I'd been going about 1.5 hours, then I noticed it had stopped blipping the throttle on downshifts (I was using the paddles in S for the most part). I found a safe place to pull over, switched the car off and searched for fault codes (didn't find anything related to this), then when I started the car again it was fine.

Prior to that, the car hadn't been driven for almost a full week. Starting to wonder if my battery is maybe showing early signs of fatigue, but then the transmission was fine to start off with, it was only after I'd been driving for a while.... Any progress with yours?

 

For me, this seems to be a cold weather issue. The battery seems to hold charge better in the summer!

 

8bit, if it was working fine initially and then stopped working, that doesn't sound like battery - 1.5 hours driving should leave the battery in a pretty good state. And, in any case, the car will be running on alternator power. It's only at startup that low battery is an issue, because it stops some of the modules from booting up properly.

 

Thanks guys. Hopefully your issue has gone away, amcdonal86

Ngarara, yeah it doesn't seem to totally add up to me either. Last time it happened it did so right from when I switched the car on. The last few drives before that I'd done had been quite short. The difference this time as you say is that it had had about 1.5 hours of working fine beforehand. I read that others have attributed this symptom to duff batteries, I guess it could be that the battery is struggling to charge and more load is being placed on the alternator while the car is running maybe?

I have had a few other minor electrical gremlins over the (almost) year since I've had the car so I'm happy to change the battery anyway. I'm planning on changing the tranny oil and filter/sump assembly soon too so hopefully that'll help. I'm sure I read somewhere else that changing the shift mech solenoids would be the next step...

 

If electrical problems start after driving a distance, one possibility is that the alternator is not putting out sufficient power, so the car is partly running on battery and thus draining it (had that problem on a Mini years ago). However, you said it went away with a restart, so that doesn't seem likely.

The systems on these cars are so complex and interrelated that a glitch in one area can have effects all over the place. It's the old IT game all over again: "Switch it off & on again".

 

In winter 2012-2013, before I had an AGM battery (just had a standard lead acid) the problem would come back repeatedly, even after restarts. I would restart, and it would go again briefly. Then it would come back after maybe 20-30 minutes. Sooner if I had the seat warmers on.

I do wonder if it has to do with the alternator.

I often wondered what this sound was:


Nobody else on the forums seems to have had this sound. It sounds similar to a rear alternator bearing noise on an F150 which is well documented. I never got around to fixing it, because it only happens in cold weather when idling, and only when the engine is cold.

 

OK thanks to both of you.

So it's feasible that the battery, alternator or combination of both could be causing electrical supply dips that may have upset the running adaptions in the transmission control memory. I have had other electrical gremlins from time to time (wing mirror memory position recall not always working, occasional touch screen stuck on Jaguar logo etc) and my car is often not used for days at a time so I think I'll try an AGM battery first and leave it for a while and see what's what.

Ngarara, I'm in the IT business also but I'm a UNIX and Storage analyst so "switch it off and on again" is a last resort to me

 

Yeah, if you're having gremlins, a battery replacement is a good place to start. And you might want to consider a battery maintainer or solar panel to keep things topped up.

I'm in IT too; solution owner, mostly networks & security (though I did design a 25 Petabyte storage array once). But that's a sales role, so it's all cost models and diagrams with fluffy clouds. I don't actually have to make it work.

 

FYI, getting an AGM battery did help reduce my electrical gremlins, but did not eliminate them completely. To really nip them in the bud, you will need a battery maintainer!