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[diffwhine]

It should be quite happy for a few weeks before the battery goes too flat to turn off the immobiliser with the plip. If you are using a Cetek (and its actually doing what it should be doing -i.e. battery maintenance, then this problem should never arise. If the battery voltage remains above about 10V, it should be enough to keep the alarm set properly. The car probably won't start, but at least you should be able to switch off the alarm!
When you say that it is immobilised, can you still activate the central locking with the plip? If that is the case, what happens next? I assume key in the ignition and switch on. Does the red immobiliser LED go out? Although its one system, the car alarm has three functions. The first is to monitor any entry through any slam panels (perimetric alarm). The second is the interior sensors (volumetric alarm). If these two are working, but the third function (immobiliser) is not deactivating, then you need to be looking at the security signal between the engine ECM and the body control module. That's a T4 / Autologic job usually.
Final thought. If the battery is good, central locking works, but the immobiliser does not deactivate when the key is inserted, does the red light go off if you press the unlock button on the plip with the ignition on? If so, it could just be a faulty passive immobilisation coil. That is fitted round the ignition switch (same on TD5 Defender). If that isn't picking up a signal from the alarm plip in close proximity, then that's an easy change.
If there is no response from either key fob with new batteries fitted, then ideally it should go onto T4 or Autologic to monitor the alarm and key inputs. It would be worth doing that anyway to try and find out what's going on. As I said before, the Discovery 2 alarm is pretty bombproof and reliable. The key remotes are usually the only obvious weak point.
A good independent LR specialist should be able to sort it out. Don't waste your money at a LR dealer - its rare to find anybody there these days who knows enough about them.

[ChrisJC]

Top tip that I have developed from my P38 which has gone flat 8 times during lockdown:
When the flattery is completely bat, unlock the drivers door with the key, pop the bonnet, then close and relock the drivers door. Open the bonnet and stick on your jump leads. The vehicle will then power up in the state that it went down, i.e. locked. Then you can use the remote to unlock it and start it in the normal way.

Doing that is much quicker than faffing about with the EKA and the horn blaring!

Chris.

[oilstain]

Just got back from the MOT - pass

The Discovery will lock/unlock and start with the key but the fob will not lock or unlock now but have good battries
The cetex seems to be working and battery is fully charged now and after putting the code in, starts with first touch of the key
All the doors lock/unlock with the dashboard switch, so wondering if its the key fob/battries, whilst the batteries are good perhaps I will get new just in case but why would it not start with the key before without inputting the code, perhaps even with a % battery if not used often this happens??

[diffwhine]

It does sound as though you have a key remote issue. Keys come from LR as a remote and key blank. You are supposed to get the key cut (or transfer to the new remote). The new remote needs coding to the vehicle using T4 or Autologic. You have to enter a long bar code number as part of security programming. Before you part with hard earned pennies, its worth paying for a quick load on a diagnostic system just to confirm.

[oilstain]

I have 3 keys, The car should have come with 2 bit the dealer lost one and got another which they coded. They then found the lost one but said as you can only have 2 keys coded to each car I should just keep the one they found as a spare.
As both the 2 "good key" fobs dont work , to me it seems not to be the key fob but the Discovery?
(In the morning I will change the battery in the other good key and try it, just to check )

[diffwhine]

That's correct. If both keys don't work, then it may be a car issue. The body control module has a capacity for something like 14 keys. By that I mean that new keys can be programmed in (I think) 14 times before it needs a new body module as well as keys. I've never seen a control module where all the key slots have been used, so that's unlikely to be a problem. Try the other remote with a new battery and fingers crossed that all it is.

[mini Anaconda]

Reading this thread with interest.
I have a 2004 D2 ES Premium that I bought at the beginning of the year - never sure if it is going to go wrong!

[diffwhine]

I've got one too. Cracking car - doesn't give any major problems. (I'm going to regret saying that now!).

[2a_Lightweight]

I had a 2004 Metropolis, made the ES premium look like a base model. Just scrapped it, complete rot box.

[oilstain]

That's correct. If both keys don't work, then it may be a car issue. The body control module has a capacity for something like 14 keys. By that I mean that new keys can be programmed in (I think) 14 times before it needs a new body module as well as keys. I've never seen a control module where all the key slots have been used, so that's unlikely to be a problem. Try the other remote with a new battery and fingers crossed that all it is.

Tried the other key fob today with good battery but no luck, so not the key fobs

[diffwhine]

Ah.. Not so simple then! I think you will need a bit of diagnostic help with this one. Pity you are not in this neck of the woods as I would have been happy to help. You need to find a garage with either T4 (TestBook) or Autologic. T4 being the original kit is probably easier in this case. Somebody needs to plug it in and go through the key and security recognition tests. Shouldn't take too long to at least diagnose and then you can decide how to proceed.
Don't rely on entering the EKA code every time, as the microswitches do fail in the latches and then you are even further up the creek...

[oilstain]

Thinking about this,
As the Discovery has only 1 of the 5 handles with a key hole I need to retain central locking
But could only have the central locking function with the key and not the fob but at times as I found recently when a idiot parked 2” against the drivers door side!
But I do not need the immobiliser function
And perhaps do not need a alarm function if unavoidable
So would it be possible to reprogram it to do this?
and end up with a usable Discovery

[Genem]

These "modern" security and other electrical systems are a pain. Its a pity its not relatively simple to disable them completely at some point in their lives - 10 years old ?

I wonder how many vehicles, perfectly good otherwise, find themselves scrapped because of a relatively minor electrical fault ?  Years ago, my wife lost confidence in our P38 when it broke down, refused to move, dashboard flashing "Gearbox problem", in the dark and tipping rain with two young children in the back.  Actual problem ? Flat battery.   

My brother in law recently found himslef locked out of his car because he left the key in the ignition but stood talking.....the car locked itself. He was taken to collect his spare key ( do we all have one ?) and on return it would not open on the fob. No visible key hole. Needed google to tell him to lever the cover off the handle, revealing the key hole underneath... Looks over Practicality...

[oilstain]

Just another thought, does the 2000MY (built in 1999?) have a port for a code reader/reprograme
I'm unable to see one

It seems a great shame that cars end up being scaped, mine has only 80.000 miles, full service history, waxoiled often and as the MOT man said, like a new underside

[Genem]

Just another thought, does the 2000MY (built in 1999?) have a port for a code reader/reprograme
I'm unable to see one

It seems a great shame that cars end up being scaped, mine has only 80.000 miles, full service history, waxoiled often and as the MOT man said, like a new underside

My little Merc just pre-dates the OBD2 common system and has a specific to Mercedes system that was used for only a couple of years in the late 90s, completely non-standard round plug. Luckily my local auto-electrical guys still have the kit to read it. Car is good, went through the MOT last week with minor advisories. ......but most garages will not be able to diagnose it if it plays up :-(