You experienced the designed progressive shut down when the battery voltage drops. Even if the battery is almost completely flat, once started the alternator provides the power. Just the same as if you were to jump start the car. The battery may be down to 9 or 10 volts but once it has been jump started and is running, the alternator powers the load as well as charging the battery. So, from that, it's pretty obvious there's nothing coming out of the alternator or, if there is, it isn't getting as far as the battery. After you charged the battery and started it, if the alternator was working properly you'd see alternator output voltage, so around 13.5-14 volts. Charge the battery again, start the car and check the voltage between ground and the output post on the alternator and compare that with the voltage at the battery. If they are the same, the alternator is dead, if there's voltage at the output of the alternator but not at the battery then it is a problem in the cable between the two. The battery may not be brilliant for it to drop that quickly once the engine was started or you just didn't charge it for long enough.

That's probably where I saw it as I've got that document and I've just had a look through it. Page 94 shows an example screenshot from Rovacom giving the Idle Air screen. That shows an idle speed of 698 rpm, with an airflow reading of 449 kg/hr (which must be wrongly displayed?) but a CLV of 21%. So maybe it is RAVE that is wrong?

The intake air sensor always seem to read low, both mine were reading around -14 when first started from cold, rising to -6 degrees once the engine had warmed up when the ambient was about 4 degrees outside. It's my understanding that this isn't important as it only does anything when the intake air temperature gets very high (+55 degrees rings a bell somewhere) so as long as it is below that it won't affect anything.

I'm glad someone else has found similar readings to mine though.

But when there is no load on the engine, although I have since read that it will be lower in Neutral than in Park although I can't see why, just revving it up to 2,500 rpm shouldn't increase the load. Or at least that's how I would see it. If anything, once things start spinning more there will be less load due to the frictional losses in the engine and the flywheel affect of the torque converter should allow it to spin more freely? Just intrigued as to why my figures are so different to what RAVE says they should be while being the same on two different cars. Unless it is something else that the Nanocom works out and displays differently to how LR would measure it. When I have another play I'll try my generic scanner and see what figures that gives.

In both cases I was running on petrol although the MAF and Calculated Load values didn't change when I switched to running on LPG.

Both my cars are GEMS and both have singlepoint LPG systems on them so there is a mixer bolted to the throttle body although I'm not sure if this is relevant. The MAF sensor on the Ascot had gone intermittent so some days it would be fine but sometimes it would give no readings (current airflow 0.0 Kg/Hr irrespective of revs) which meant it was a bit of a bitch to start unless I forced it to start on LPG. Bought a replacement MAF sensor, genuine Sagem with a manufactured date of 10/07, so a recent one. The MAF on my car was an aftermarket one so decided I would fit the replacement to mine but would check the readings I was getting before swapping them over.

Checked the readings on my car and found them to be about right, around 22 Kg/Hr at idle, rising steadily up to around 60-65 Kg/Hr at 2,000 rpm. RAVE tuning data says it should be 20 plus/minus 3 at idle (so within limits) rising to 60 plus/minus 3 at 2,500 rpm (so a little on the high side) However, when I checked the Calculated Load Value, it was hovering around the 23-24% mark at idle in Park and not the 2.8-3.8% that RAVE says it should be. Initially thought that maybe there was a decimal point in the wrong place error in the Nano but at 2,000 rpm I was showing a calculated load value of 35-40% and not the 10% at 2,500 rpm I should be seeing. Swapped the MAF sensors so I now had the genuine Sagem replacement and checked again. Readings were damn near exactly the same.

Then fitted the known working aftermarket MAF I had just taken off my car and put it on the Ascot. Fired up immediately and left it running to warm up. Then checked the readings and they were almost identical to on mine. Airflow within limits at idle, slightly high at 2,000 rpm but still with a calculated load value far higher than it should be. I reset the adaptive values on both cars so had a baseline to work from but that made no difference to the calculated load value.

I'm wondering if the restriction caused by the mixer in the intake is affecting anything and will see if removing it makes any difference (when it's a bit warmer outside) but does anyone have any idea why the MAF readings seem about right yet the calculated load value is much higher than it should be?

Do you get a Sunroof Not Set message on the dash? If the sunroof is there but not working (and hasn't been reset since the battery was last off), then you will get a warning on the dash. The way to stop the warning is to go into the BeCM settings and change Sunroof to Disabled. That way the BeCM thinks you don't have one so doesn't give the warning. However, as it doesn't think you've got one, it won't allow you to operate it so even if the switch and motor are fine, it still isn't going to work.

A couple of people with an unexplained battery drain problem have found corrosion on the interior light. Disconnecting it or replacing it has cured the battery drain.

I'm still here, but not for much longer, just waiting for the bathroom to become free. Dunno if it was the same for anyone else but the lack of fireworks in London seemed to mean that everyone else was letting some off. I though WW3 had started up outside!! Or maybe it was Symes giving his Vogue a Viking funeral......

Or 81p from RS Components. See here https://rangerovers.pub/topic/2147-heater-core-temperature-sensor-thermistor

Isn't this the car that had all sorts of extra wiring behind the dash when you got it? In which case it's quite possible the engine run signal has been disconnected by accident.

No, BeCM doesn't control the HEVAC, more the other way round, although it does have an internal relay that supplies power to the heated rear window. It isn't involved at all for the heated front screen, the HEVAC pulls in the two relays in the underbonnet fusebox. But it does supply power for the heated seats.

What makes you think that? I did wonder if the BeCM had been swapped for a low line one but having checked, the BeCM doesn't have anything to do with the front or rear screens. It supplies power to the seat heaters but that is all.

You're not the only one. Each of the buttons has an LED behind it so it isn't like the illumination that uses a couple of bulbs and a light pipe. If you've changed the HEVAC and the replacement is the same that would appear to rule that out too. The HEVAC may have some sort of sensing to check that what you have switched on is doing something. Check if relay 5 operates when you switch the heated screen on (when relay 5 operates it powers one side of the screen and also pulls in relay 4 to power the other side). Maybe if it doesn't see a load it won't illuminate the LED. Front and rear screen operation is inhibited if the engine isn't running so maybe the HEVAC isn't seeing the signal to show that. Seat heaters are inhibited if a rear window or the sunroof is either in operation or unset as they use the same power supply and it is to protect the circuit from being overloaded.

Do the other buttons light up, the ones along the bottom that adjust where the airflow goes?

Heated seats rarely work these days, people will insist on sitting on the seats which breaks the elements. How to repair is here http://rrnet.gadsdenrovers.com/repairdetails/seats/seatheat.html. Heated windscreen switch should operate relays 4 and 5 as it is split into left and right sides but where the elements connect at the edges of the screen can come adrift. Usually what happens is it goes in sections, this was mine a couple of years ago when the passenger side was still working but the drivers side had lost a few sections
.
Now I'm down to a few strips on the passenger side and none on the drivers.

Rear screen is fed from Fuse 12 via an internal relay in the BeCM. Check to see if you get 12V on one side when it is switched on.

Doesn't really matter, either closed or tilted, although tilted might be easier.

You'll need to take the glass out. Slide the plastic covers on each side (forward if I remember right) so they come off and undo the two Torx screws on each side that hold the glass to the mechanism and lift it out. The seal is there to keep wind noise down, not to stop water getting in, the drains are there to get rid of it once it is there. You'll need to drop the headlining out to get to where they are attached to the sunroof cassette (so you may as well retrim it while it is out.....).

The heated screen button on the HEVAC will be at the top left, above the heated rear screen button. If you've got that button but no heated screen (and probably a gap in the fusebox where relays 4 and 5 would be), then the HEVAC has been replaced with one from a car with screen heater. The larger button, low down on the right is usually marked PROG and is the demist program. If puts the airflow to the screen, the temperature on full heat, the AC on so you get dried air onto the screen, the fans on full and the heated screen (where fitted) and heated rear screen on. One button to poke instead of messing with lots of others.

Inside of the sunroof will get a lot of condensation on it if there is moisture in the car. So if you have a leak somewhere, the moisture that gets in will stay there until the car sits in the sun or gets warm inside when you use it and it will then condense on any cold surface, like the inside of the sunroof or windscreen.

I bought a spares or repair 4.0 SE that needed head gaskets and a few other small bits doing to put it back on the road. Got it running and used it for a bit, loaned it to my daughter for a month when her car packed up in the middle of winter and I didn't feel like spending the time on it in freezing conditions and planned on finishing off a few minor jobs before putting it up for sale. Walked past it one morning and noticed it had developed a crack in the screen, directly in the drivers eyeline. When I had bought it the owner told me the screen had been replaced recently. Took it into a local Autoglass depot and the guy told me the screen had been replaced when he was still 10 feet away from it. He could see immediately it had been done and whoever had done it hadn't put the rubber covers on the steel lugs that stop the screen from sliding downwards so contact with the metal had caused a crack to appear which was slowly working it's way up the screen. Cheapest deal they could offer on a heated screen was £525 and, as it wasn't covered by insurance (trade policy), I sold it as it was with no chance of being able to get an MoT. The guy that bought it intended using it as a donor for one he was restoring but when he saw it couldn't decide which he would use as a donor.