There have been further developments.....
Lately, it has been "occasionally" telling me the license plate bulb is out. Taillights are ok
The really odd one is the trailer indicator (Symbol of a trailer) has been flashing along with the LH turn indicator.
But not all the time, and maybe just a few blinks when it does do it.
Does that bit of information jog anyone's memory? Am I perhaps chasing a bad underbonnet fusebox?
Fuel gauge is still a bit out of whack. It ran out of fuel in 35 miles after it went to <50 miles. (I had spare petrol with me)
I don't mind it being a bit nuts at 3/4 and above, but I like to know when I am at the bottom, that I really am!
Which pots were calibration for that again?

Granted, this site is blessedly "Brit-Centric" in nature, however there are still a lot of owners all over the world, including, YES! here in the former colony AKA the USA.
Tragically, here, I have seen over a hundred very nice, mostly under 150k miles (I have had great luck in jumping in a small battery and reading the Becm for mileage) clean examples in breakers yards with unknown issues.
No way to know what the final straw was with most of them, but due to the lack of real mechanics over here who are willing to even look at one of "Those things" and the sad fact that there is no shortage of unethical charlatans who are perfectly willing to take enormous sums of money to fix something, only to get it wrong, at best and make things worse usually.
As with everywhere I am aware of, the old skilled trained experienced guys are getting pretty thin on the ground.
I suspect most of them on your side of the ditch are on this forum!
So, to answer your question:
I have tested this with all 3 of my P-38s, and if I intentionally immobilise the BECM I can immediately start the vehicle, and, strangely, there are no messages in the console, and everything works as usual.
The only indication that appears is the red led on the dash will be flashing to indicate it thinks the alarm is on.
Having disconnected the alarm horn long ago, I don't know that it would not be bleating like Shaun the Sheep!
So, if the S-chip is a method of keeping people from getting immobilised due to their lack of knowledge of the proper maintenance procedures for the locking system, then I say, sell one to everyone who has had immobiliser issues!
Remember, they may be capable of learning to fix things in time if they don't get so pissed off and disgusted that they torch, or trash a perfectly serviceable vehicle. The fact that they ask questions (Over and over again) about issues they are having shows at least a willingness to give it a go.
Who has the sign off: "Land Rover, making mechanics out of drivers since 1945"
Never were more true words spoken!
Stepping down from soap box now......

The door latch or Nano and EKA tricks might work, but I am assuming that this one has been annoyed until it has gone into what I think of as "Secondary lockdown"" The only way out of that is for the BECM to take a trip to someone with full BBS setup or testbook for unlocking.....$$$$$$
OR the Psidoc solution is quicker, cheaper, and foolproof. (and forever)
NO I do not work for, or in any way receive compensation from Simon.
I just love his product and want to keep as many P-38s out of the breakers yard due to immobilisation issues as possible.

Someone needs to get one of Psidoc's chipped unlocked ECU units and go plug it in and drive it off.
About a 5 minute job!
I would love to see the look on the seller's face!

Was going to attack this issue this morning, but it seems to have miraculously healed itself.....For now......

Of course, this is the '99 with the randomly wonky fuel gauge as well.....That seems stable for the moment too......

OK,
I have sussed the problem(s)
First and foremost is that when it comes to the recirculation flap motors, the Nano, or at least mine. IS Dyslectic!!
It has been pointing to the LEFT recirc motor, when it was the RIGHT motor all along.
Since these motors seem to be a rare failure, it's possible this is not a well known bug?
To find this, I just looked down the pollen filter holes, and observed the Left flap moves just fine, whilst the Right flap is a non player!
Pulled the kick panel, unplugged RH motor, and tested. It came up Open circuit instead of shorted.
Putting a motor only from a blend motor on the RH side cleared that fault, and only then did it detect the Left hand motor being unplugged??!!
Interesting to note, the HVAC controller did not throw an open circuit fault when the Left hand motor was unplugged.
So, if it finds one recirc motor fault, it seems to stop looking for another. Curious.......
In any event, I will now look into replacing the RIGHT hand motor, which looks easier to get at than the Left! (Yea, Riiiight...)

3rd new fuel pump/ sender and it seems to be playing well. We shall see........
Thanks for the help!

Got a new one on the '99
Last night, I went for a drive and within about 30 seconds of setting out, with lights on, I got 3 messages:
RH Tail Bulb out, LH Tail Bulb out, License plate lamp bulb out.
Upon inspection, all 3 lights were merrily shining away. Shut off and upon re starting, got the same thing.
I have checked RAVE thinking it was possibly an earth issue. Found that they do not share a common Earth point, so non starter there.
Any clues as to where I look from here?

Sorry, I failed to mention that with the motor unplugged as well as with the wires going to the motor plug
cut at the HVAC plug, it is consistently reporting "Motor is short circuit to Pos 12v"
I am indeed trying a blend motor as a substitute as you had suggested on the dark side sometime back.

I did notice that since the HVAC only does a calibration every 6 or so cycles of the ignition that
with motor plugged in, and error cleared, it would stay cleared until it tried to do a scheduled calibration.
Now, it seems I cannot even clear the fault.
I do cycle the ignition after clearing fault as Marty suggested......

Having fixed the issues on the RT side with distribution motor, I have turned my attention to the LH side distribution flap motor.
Nano shows error as "Motor short circuit to 12 volt positive"
The motor moves the flap just fine from recirc to fresh.
I have unplugged the motor and substituted in a blend motor with a good drive. Works fine. Same error.
I found the 2 wires at the HVAC head unit plug and snipped them and attached motor directly to the plug.
Same error.
I have swapped in 2 different known good, tested working head units and same error.
What am I missing? Nothing in that circuit is shorted to positive anywhere???!

YEA!!!
Got the Rt angle ratcheting driver, cut a bit in half with disc grinder, got out the 3 top screws and one on the Rt side
and was able to get in and push the 2 small tabs on the cable cassette and pop it out.
Released the latch and dropped glove box door.
Something to note: When I tested the push button release, the cable seemed to be bound up somewhere.
I had moved it out of the way and the new routing was not enough of smooth curve, so I re routed it and got immediate smooth operation.
Bunged in the cassette, Put it all back together, and it's now working perfectly! 15 min. start to finish, and nothing damaged!
Cheers!

Well, it's not so much an "Issue" as a real boneheaded maneuver.
I was replacing the diversion blend motor on the RH side of my LH drive '99. went well, and no more checkbook.
Having done the heater core on my 02, I was just breezing away putting everything back together, because I knew what I was about!
Replaced glove box fascia, having smoothly clipped in the cable release cassette........Without checking to be sure it was engaged....OOPs
Put in hinge fasteners and attempted to open the glovebox. Yea, Right! Latched, and the cable is not engaged.
So, what is the approved procedure for extricating myself from this??? Non destructively preferred.
I suppose it is the same as if the cable broke at the latch??
Thanks in advance for any suggestions!
Cheers!!

Edit...An hour later......
Had something to eat (And Drink!) and had another look.
I am guessing that if I use my super shallow ratcheting screwdriver, I will be able to remove at least the screws along the top of the
piece that holds the top in. Then attempt to either re seat the cassette or jigger the release with picks?
Fortunately, the aforementioned ratchet driver is in the tool kit on boat, so my only option tonight is another G&T.....
Any refinements cheerfully welcome!

Ahhh.....
You have an alter ego on the dark side!
Kinda like Richard/ Gilbert.....
Yep!
Sounds knackered. See troubleshooting procedures on dark side.
Cheers!

So, it's not just me? Hmmmmm....

I have noticed that it will come up with an accurate reading then change when engine is running.
Also that cycling the engine on and off will trigger a change. Always 1/4 tank...
Adding or subtracting loads has no effect that I can corroborate.
Earths good.
I will be getting under the seat to look at the BECM soon.
If I find no obvious issue,
I have a cloned spare for Bolt I will try.
Just trying to remember how many miles it has stored as it will reprogram the odo on the 99.....not really a big deal as it should be close to what is on the 99.
No issue with immobilizer as I have a Psidoc chip in the ECU.

PS: Things seem to be getting a bit hot on the dark side! "Go ahead, make my day"
Sounds a bit like a certain politician with bad hair! ( No, not Boris)

Arrrggggghhhh!!!!!!
I made up a cheater plug for the top of the fuel pump so that I can drive whilst substituting in various fixed resistors
feeding the resistance directly to the BECM via the pump plug.
I needed to do this as there is something changing on a dynamic basis while driving.
What I have observed so far is that with 150 ohms in, it reads about 1/8 tank. No fuel range light yet..
Drive a bit, and it will quickly twitch up 1/4 tank and stay stable there. No correlation between lights on/ off brake pump running / off.
When I switched in 67 ohms, it read just above 1/2 and was fine until, while driving, it went up the 1/4 tank increment.
No wonder that when it is actually full, the gauge freaks out for the first 1/4 tank as it is seeing the signal as out of range.
The resistance is not changing, yet the gauge is?????
So, as this is a signal that is being sent to the cluster as a digital stream, would I possibly be correct in pointing to the Becm as the possible
culprit?. I realise it gets blamed for many things and is rarely at fault however as the PO had their shop remove the Becm and send it to Turners
at at least one point, I am guessing someone messed around in there.
I have a spare board for the Becm that is allegedly a clone of the original, or is perhaps the original..
This is getting ridiculous to the point of being fun now!

Edit: The bad news is that the board I have is a power board.....The good news is that it looks to be in very good condition......No help for this one however.
Guess I will get inside the box and have a look for corrosion, etc.

Well, you mentioned that you were answering questions from Calais.....
I shall officially amend my salutation to "Hope you enjoy(ed) your Banzi run
In the Plod...."

Ahhh, thanks.
I recall that thread.
I will have a play with it this morning.
Also need to get rid of the annoying 5mph error on my 02.
Cheers!
Enjoy your holidays!!

Yep!
What you have here looks like your basic AI hack.
Very generic questions.
Annoying. But clever.....

Thanks, that's actually the next step.
I'm rummaging around the shed looking for the box of pots to do just that.
Thanks for the numbers!
It's possible the PO or his "expert" shop have screwed around with the calibration.
Got a message center bulb to replace anyway so I will have a play with it.
I guess just fill it up and adjust as appropriate.

Everyone??
Ahem.....
Careful how widely you tar us over here with that very wide brush you are using....
There are a lot of us all over the planet that want to keep things just as they're designed, thank you very much!

Having stepped off of my soap box, I can certainly appreciate your take on the unwashed masses that are currently teeming on the dark side!
Some of your answers are vintage Toad Hall!!!
Got me laughing several times.
Do you also have an urge to drink good single malt from the bottle with a straw
Whilst you moderate over there?
Keep up the good work. You are appreciated wether it seems like it or not.

Now, could you please send me a tacho conversation box for a 454 big block Ford I am installing?