So, an update...

Just ran over to the shop to see what was up as they have had the truck for a week and not told me anything!

So, it seems for the most part I have managed to stump all of LR with this one.
The little indi shop got Land Rover Birmingham involved and they looked at it for a day or two, and were stumped.
They suggested getting LR North America involved... So they call them up, send them logs and data snaps and wait. They are baffled and tell them to call England.
So, first he calls a friend of his who is a LR tech in England and he's stumped as well and tells them to call LR England.
So, they call LR england, send them the logs and data last week. Just heard back this morning, and they are at a loss as well...

They think they have narrowed it down to 3 potential items, BUT, the part that none of them get, is why it will start after you let it sit and it pulls up the transmission fault.

The options are, the transfer case ECU, the transmission ECU (just WONDERFUL) or my personal favorite, the thermostat.
LR NA and England both said they really couldn't narrow it down further until they got rid of the thermostat code, so they are supposed to get the new thermostat in today and see...

Nobody really has much hope of that fixing it, but the most interesting thing to me is that none of them are certain enough of that to say that they think it stands little to no chance of fixing it.

Anybody know how much a transmission controller should run? He's throwing out numbers like $2600 to $3800... Which sounds a bit high, but unfortunately not out of the question for our wonderful cars!

Also, what do you guys think the odds on which of those three being the real source of the problem?
Never had any issues with the transmission that I can tell, always seen it respond very well both mechanically and electronically (at least as far as shifting and sport mode and so on) although I just rolled over 223k miles...
The transfer case controller, looks to be in pretty good shape, I pulled it out the other day and didn't see any obvious issues either wiring or case wise...
And the thermostat, would think that I would have seen some issues with either actual engine temp or reported temp and wouldn't think it would just stop working one day?

 

Regarding the thermostat, oddly enough, I had another car where it went bad and the car wouldn't start in cold weather. It would just crank and crank and crank. Replaced it and the problem went away. So it can cause the car to behave oddly, probably messing with fuel mixture and such. But yeah usually you notice when it never reaches normal temperature or if the temperature drops on the highway.

Anecdotally, these LR3's tend to throw a transmission fault message whenever anything goes wrong, transmission related or not, so hopefully there's nothing wrong there.

As for the transfer case ECU, there are a few stories of how water ingress has caused all kinds of electrical nightmares with it, so it is very possible. Usually triggered by washing the engine bay or maybe in your case, heavy downpours. Have you checked your windshield cowling for bowing or gaps?

 

Unless the cowling is stupidly bad, the water that runs between the bowed cowling and the glass typically flows into a channel under the wipers that contains the HVAC intake, which may get some water into it. The transfer case ECU is behind the fuse and battery box, and is protected by the sheet metal channel.

If the battery box is missing its lid or the bonnet is left open, water can drip into the area behind the lid/battery/fuse box. Mine was destroyed when a dealer wash crew decided to remove my battery box cover and hose down the entire engine bay. Kid you not, the techs had to immediately remove my fuse box and most of the ECU's in that area, dry them, and couldn't save the TC ECU.

 

While you are doing thermostat things, look at the wiring going to the oil temperature sensor located down near the oil filter.

The oil temp sensor and the water temp sensor are somehow tied together via the Engine computer. Apparently a failure or odd readings from the coolant temp sensor are checked against oil temperature readings by the engine computer.

Also a wiring problem, (ie, the mice ate the wires), to the coolant sensor can cause odd problems - no start and the like.

Also, is the engine temperature gauge reading oddly or intermittent?

The big connector feeding into the rear of the instrument panel printed circuit board can come loose, (not off, just loose). That affects the signal into the backup memory chip located on the instrument panel pcb. The only visible indication of a loose connector other than weird problems can be that the temperature gauge does not seem to read correctly or is intermittent.

And as said in a post above, weird non tranny problems seem to end up affecting the transmission and making it look sick.

 

Yeah, I'm really hoping for some sensor somewhere to be out and causing the problem...
Really can't afford to put a transmission controller in the stupid thing.

The guys at the shop are supposed to be putting the new thermostat and everything on this morning and resetting everything and seeing what they get.
If that doesn't just take care of it by it self, I'll get them to check the oil temp sensor too.
Assuming that's not an issue as well I think I'm going to get them to just try and reflash the ECM and transmission controller and see what happens...
Not like it could break it much worse at this point.

 

Check this...

https://landroverforums.com/forum/lr...re-deux-81641/