Disco 4 (LR4) Help please

Hi all very impressive knowledge reading through the threads on this forum I don’t suppose any has ever experienced this sort of fault. Drive along and all of a sudden goes into limp mode and all the dash lights come on every single one the information screen displays every fault you can think off. Every system unavailable. Stop switch it off and re start the engine management light stays on and says eco mode unavailable. The car runs fine. Eventually the engine management light goes off. Then a few more miles down the road it happens again.

Maybe your battery and alternator are not as they should be?
What Battery volts do you have with everything off, with just ignition on, when cranking?
What battery volts do you have when the car is revving at c.2,000rpm with everything switched on (lights/A/C/Heated seats/screens etc.)?

I took it to Halfords of all places as that was the only place open when we were on our way home. They tested the battery and alternator and said everything was ok.

Awgodsall said:

I took it to Halfords of all places as that was the only place open when we were on our way home. They tested the battery and alternator and said everything was ok.

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Okay may not be good enough, the larger land rovers love a good battery.
The cheapest of the cheap multimeters off ebay etc will do you for testing battery and alt voltages.

you had the battery checked was this in the vehicle what equipment did they check the battery with (load tester or volt meter)
and you have checked that the battery connections are secure and tight

They just put a tester on the battery it was reading 16 volts which I thought was too high. But the chap said it was fine. All the connections are tight. They didn’t test the start stop battery. I only took it there as was only place open. I’m trying to get it booked into a Land Rover specialist This week.

It's worth checking all the earths, especially the one under the o/s fr. wheel arch liner (I think that's where it's located) as @gstuart mentions this as it's a often overlooked earth to check He's posted pictures on here if you search his posts.

Awgodsall said:

They just put a tester on the battery it was reading 16 volts which I thought was too high. But the chap said it was fine. All the connections are tight. They didn’t test the start stop battery. I only took it there as was only place open. I’m trying to get it booked into a Land Rover specialist This week.

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16 volts is to high.
D3 max volts is approx 15.1/2 in the depths of winter, I ahve a volt gaige on the dash and it is the same year after year.
D4 normal batteries much the same voltages.
D4 with AGM batteries runs at a lower voltage.

So I would conclude your alternator is duff, which in turn may have screwed the battery.

I bet @gstuart will know the D4 volts, but he will need to know the year of your car

I would get the battery's checked by someone who has the equipment to measure the cold crank current etc and knowledge of battery's not by a counter expert or a want to be land rover mechanic is not the eco reliant on the stop start battery

In my experience, a higher than normal charge voltage is because the battery is fubar, and unable to absorb the extra energy.

Hi

Plus 1 what’s already been mentioned , indeed 16 Vdc is too high for a D4 , max for the AGM batteries is 14.8 Volts., D3 is 16.5 Vdc

here’s also a picture ref that earth lead thats behind the front OS wheel arch liner

plus 1 in getting a multimeter , see what the battery is with the engine off and then engine running , followed by putting everything on, Ie lights , AC etc , then raise it to 2,000 revs and see what the Vdc is , then with the engine still running at idle , meter set to ACV , put the test probes across both battery terminals and read the voltage ,

For testing grounds , go from the positive battery post to a ground u wish to test

lhas the BMS module been reset and put onto diagnostics as that’s also a very useful knowing if there’s any codes

at the end of the day if it is at 16 Vdc that will as indeed mentioned screw ur AGM battery up so will req replacement but only after the alternator is fully checked out , if the alternator needs replacing it must be a Denso

would u be so kind to let us know what year the D4 is and if it’s a stop start plse , thks

hope that also helps u

ps, battery should be a minimum of 825 amps - 90 A/H

I’ve just checked it again with my multimeter on the main battery I have 12.42 v with engine off when charging I have 14.8. The smaller battery the other side of the engine bay o have 13.36 when engine off 14.43 when charging
When reving at 2000 rpm main battery was stayed at 14.8 then dropped to 14.03 and back and forth
The small battery stayed the same at 13.36

The discovery is a 2014 on a 14 plate and it does have stop start many thanks Adam

You have a smart charging system on the D4 as the battery gets weak the car demands more power from the alternator hence getting 16volts when running and when checked by halfrauds .

Replace the battery but you then need to tell the car it has a new battery or it will keep pumping 16volts into it and cook it pretty damp quick.

Hi all do the disco has been in the garage since Tuesday. Brilliant group of guys. They know it’s loosing its high speed can-bus. But they’re having a hard time finding what the cause is. Typically the car has behaved itself on the four test drives they have done. But they’re leaning towards either the battery because the one on there is not a good quality make or the battery monitoring system. There is a relatively new alternator on it which tell me that this problem has been on the car for a while. Why did I have to buy one with electrical gremlins lol

Hi

first i would see what make the alternator is plse as if it’s not a Denso it will req replacement , there extremely fussy

if it’s got a high speed canbus error they should be able to trace which module is causing the issue, including live data logging along with the 5 Vdc reference voltage supply and testing earths with multimeters or a graphing meter

indeed a bad battery or alternator will cause havoc on the system

been there done that when I had a serious canbus issue which I managed to track down by going through the system step by step

They’re suspecting the battery monitoring system. Why would alternator manufacturer make such a difference.

Denso was the original make for the vehicle , other copies can throw the system haywire

have got a few more ideas but don’t wish to come across as a clever clogs with them being specialist's

fingers crossed there be able to resolve the issue

What other ideas do u have. I’ve asked them to check the alternator make. I do appreciate your help gstuart as I do all the other people that have commented and offered advice.

I do have a video you can’t put them on here can u

If it's a stop start car, it needs an agm battery. When either the main battery or second battery are replaced the car needs to be told via diagnostics to reset the charge rates or it'll cause premature battery failure. Also check the charge device near the second battery for loose or burnt terminals. The plastic coverd nuts that hold the cables tight could be burnt. Replace them for traditional nuts as a safe guard. They heat up and lose grip of the cables resulting in shorts through the wires.