2011 LR4 with 40K miles only.
Driving the other day I had HDC not available, then EBA not available then DSC not available. Then the suspension drops.
Today, twice, I then get a series of other warnings - gearbox, suspension, handbrake, drive less than 50kms etc etc. The engine warning light came on and stays on. If I stop and restart, the warnings all go away except the engine warning which stays on without flickering. When I restart I can raise the suspension again.
The LR garage says it has never seen anything like this and has no idea at all but will try to do a diagnostic which will cost me a fortune no doubt. I am not confident.
When I get the first three (HDC,DSC,EBA) this is typically an ABS sensor fault but the others are weird.
Any ideas at all? Here's the list of ODB codes

U0121-00 (2C) Lost communication with ABS control module
( on 07-12-2021 11:40:09 at 61304 km )

U0128-00 (2C) Lost communication with parking brake control module
( on 07-12-2021 11:40:12 at 61304 km )

U0100-00 (2C) Lost communication with engine control module/powertrain control module 'A'
( on 07-12-2021 11:40:13 at 61304 km )

U0101-00 (2C) Lost communication with transmission control module
( on 07-12-2021 11:40:12 at 61304 km )

U0001-88 (2C) High speed CAN communication bus - Bus signal/message failure - bus is off
( on 07-12-2021 11:40:15 at 61304 km )

U0004-00 (2C) High speed CAN communication bus (+) low
( on 07-12-2021 11:40:16 at 61304 km )

IPC-Instrument Pack

U0001-88 (2E) High speed CAN communication bus - Bus signal/message failure - bus is off
( on 07-12-2021 11:40:15 at 61304 km )

U0100-00 (2E) Lost communication with engine control module/powertrain control module 'A'
( on 07-12-2021 11:40:13 at 61304 km )

U0101-00 (2E) Lost communication with transmission control module
( on 07-12-2021 11:40:13 at 61304 km )

U0102-00 (2E) Lost communication with transfer case control module
( on 07-12-2021 11:40:15 at 61304 km )

U0121-00 (2E) Lost communication with ABS control module
( on 07-12-2021 11:40:15 )

U0126-00 (2E) Lost communication with steering angle sensor module
( on 07-12-2021 11:40:15 at 61304 km )

U0128-00 (2E) Lost communication with parking brake control module
( on 07-12-2021 11:40:15 )

U0132-00 (2E) Lost communication with ride level control module
( on 07-12-2021 11:40:15 at 61304 km )

U0138-00 (2E) Lost communication with all terrain control module
( on 07-12-2021 11:40:15 at 61304 km )

U0141-00 (2E) Lost communication with the body control module A
( on 07-12-2021 11:40:15 at 61304 km )

U0151-00 (2E) Lost communication with restraints control module
( on 07-12-2021 11:40:15 at 61304 km )

PBM-Parking Brake

U0140-00 (28) Lost communication with body control module
( on 07-12-2021 11:38:59 at 61303 km )

U0121-00 (28) Lost communication with ABS control module
( on 07-12-2021 11:40:07 at 61304 km )

U0100-00 (28) Lost communication with engine control module/powertrain control module 'A'
( on 07-12-2021 11:40:12 at 61304 km )

U0073-88 (28) Control module communication bus off - Bus signal/message failure - bus is off
( on 07-12-2021 11:40:12 at 61304 km )

U0101-00 (28) Lost communication with transmission control module
( on 07-12-2021 11:40:12 at 61304 km )

U0403-00 (28) Invalid data received from transfer case control module
( on 07-12-2021 11:40:12 at 61304 km )

 

I’m probably not going to say anything you haven’t already read about, but …

Very first thing to check is your battery and alternator. Not sure about the 2011’s, but the newer models have a battery management system that shuts down non-essential functions when it senses that the battery is starting to run low (which can be the battery, alternator, or both). Pop the hood, let it set for a good 10-15 minutes to make sure all the systems are off (good idea to keep the key away from the vehicle as that tends to turn certain functions “on”) and check the voltage with a multimeter. You should see 12.6v for a healthy battery. 12v is basically dead, and 12.4 is something like 60% if I recall correctly. Then, with engine running, check voltage again - you should see about 14v or so indicating a good charge from the alternator.

If it’s not the charging system, the other common problem that causes a ton of errors is water in the passenger side footwell from a sunroof drain leak. Even if something like that happened some time ago, the eventual corrosion can cause these kinds of problems.

If it’s neither of those things, I’d get the wiring diagram and trace the high speed CAN bus from these different modules. They are all communication errors - no “P” codes listed. There might be one COM module failing that is connected to everything else, or one common bus connection.

 

Excellent and thanks for the advice. I did notice that the display said 14.5v when the engine was running (this was when the thing was haywire and there were no other display items. I will try wht ou suggest and let you know.
Thnaks once more

 

Now - mea culpa..
I checked the battery (which is a fillable type and not sealed for life) I naively, like most owners I suspect, thought that there would be the traditional signs of battery failure - like it not starting or dim lights or a dashboard warning..
With the battery in place and connected, it measures NEARLY 12 volts!! In other words it is dud.
Since it is a non-sealed version, is it worth replacing the acid ow will it just extend its life by a week or so :-) ?
Can I use a sealed-for-life battery in its place or does LR have some special needs?

If this works, I owe you at least one beer!

 

Having left the car a while it is now 12.5ish and when running it is 14.6.
I am going to try a new battery anyway

 

Before I changed the battery I had the normal display and now and again it displayed 'voltage 14.7'
Now it seems to alternate between normal and this voltage message! Any ideas why?

 

I had the IID tool plugged in..

 

All the errors are C errors which GAP tell me can be safely ignored since the CAN protocols are 'fire and forget'.
The LR garage told me that they had never seen or heard of this phenomenon and took a very disinterested look at the errors list and clearly know nothing about CAN.
I have no road tested yet since it is snowing here but will report progress in a couple of days.

 

14 volts is the alternator, not the battery

battery should be greater than 12.6 volts after sitting with the engine off

if alternator voltage and varying greatly, typically either above 14 volts volts or below 14 volts, likely alternator is failing, had that problem (non stop canbus errors) earlier this year, main dealer couldn't figure it out despite alternator voltage all over the place so I replaced it myself and no further errors nearly a year later

 

The later measurement is probably correct - there are lots of electronic systems that stay running after the ignition is on, and even some that start up everytime the key is in proximity. That’s why you need to actually pop the hood, then let it set for 10 min or so to get a correct voltage reading. However, under 12v to 12.5v is a big difference, so the battery could still be weak. If it’s 4-5 years old, I’d just replace it, but you could have it tested at an auto store with a more sophisticated tester.

I don’t know if “ignored” is the right way to look at it. They are all comm codes, so nothing that is pointing to a mechanical failure, but there is clearly something going on with the comms. Looking more carefully at the list of codes, I think the “bus-off” codes are a little concerning. Could still be caused by a low voltage condition, but might also be something else, like a bad connection at one of the harness junctions. Might also check the main earth strap at the battery. I’ve read that they are susceptible to corrosion. I think it grounds out somewhere in the passenger side wheel well (though maybe the other side in the UK).