New to the forums, not new to Land Rover or Jaguar.

Here is the story:

MY2015 SCV6 LR4 LUX now with about 97,000 miles and just recently on its 4th AGM main battery. BMS was replaced a couple of years ago, has had numerous secondary ECO start/stop batteries and its third main AGM battery needed replacing after less than 3 years of age. It's a daily driver but a couple of times per year I have used a CTEK on it. A few months ago the third battery went flat without warning. Alternator showed over 14 volts at all times and no DTCs but battery would not charge past 12.1 volts and the starter would struggle. Battery replaced under prorated warranty and I reset the BMS with SDD. Everything was fine after.

A couple of weeks ago the EPB began showing an intermittent fault in the cluster along with the red flashing lamp and solid amber brake warning. I say intermittent because to would not always appear on a drive or it would come and go in the midst of a drive. SDD only showed a DTC for lost communication with EPB module.

Then last week, 2 days in a row and multiple times per day, the EPB fault would appear followed shortly thereafter by a complete vehicle shut down. Ignition cycling made no change, to get the car to work again either I'd have to disconnect the battery terminals or perform a reset and clear with SDD. For those days I would place the battery on the CTEK just to be certain the battery had a full charge. Each time, SDD showed that EVERY single high speed canBUS module had lost communication. Since I know little about canBUS diagnosis and the failures appeared to be brought about each time the EPB lost communication, I made the assumption this was not a coincidence and decided to try an experiment. I removed the fuse to the EPB. Drove the car for 3 full days and over 100 miles with only an amber brake lamp illuminated. I gave myself a good pat on the back and immediately EPB fault returned accompanied by every other possible high speed canBUS module failure.

So I decided to check the battery voltage and was surprised to find it read 12.1 volts. Now I understand that BMS as part of its routine, will deliberately discharge the battery but now I am thoroughly perplexed...is something on the high speed canBUS failing? Is the EPB causing issues? Is the BMS having issues again? Or do I have yet another bad battery?

Many thanks in advance!

 

Communication errors are normally cascading. I have found that the LIN, and thereby the canbus system, is quite fickle. Here was my struggle : https://www.landroverworld.org/threa...learned.42404/

it illustrates that a non-functioning part (or it's complete removal) affects things you would not think that it would--in my example, the removal of the PSDB caused the heated windshield and steering wheel to stop working.

does the gateway module have any stored codes when queried in SDD? Does it have the latest software update?

Try removing the ground cable from the start stop battery. Yes, you will get the ECO light. But, it should also shut off the BMS without affecting the gateway module. If that doesn't work, try disconnecting the BMS plug from the cranking battery. Either way, we are trying to force the computer to apply full charge to the battery and not meter it.

hopefully, the increased voltage will eliminate the EPB fault.

 

I have not checked the software on the gateway module and have never had any of these canBUS issues until now. I understand canBUS is a cascading domino and for me the challenge is identifying the module that is truly faulty. The eco battery has been dead for over 2 years shortly after having it replaced on warranty, I've attempted reviving it with the CTEK but it won't go past .1 volts and it has been replaced so many times prior that I've given up. Alternator is reading 14.5 volts every time I check. After a charge on the CTEK, main battery reads 13.5 volts but if I go for a 30 minute drive, the battery will read in the low 12s. I can remove the negative cable from the eco battery and see what if any change that makes.

As a side note, may or may not be relevant, there has always been an odd issue with the engine running rough (strong vibration, shake and shudder) when in idle IF there are electrics running at the same time such as lights, seat heaters, music, A/C compressor, suspension compressor or turning the steering wheel while parked. With all electrics switched off, the engine is as smooth as can be. Several main dealers have had a look but none have been able to find anything out of order. I've had most hoses and pipes replaced, a couple of water pumps, thermostat, belts, pulleys, gaskets, spark plugs, radiator, etc.

 

Not much of an update, issues still persist but nothing's consistent and all DTCs are random. Sometimes the car won't even turn off even with a message centre notification that the engine stop button has been pressed. Some times the rotarty shifter won't turn and once it automatically went from drive to park on its own. I've been monitoring the battery and it always seems to measure in the low 12s - 12.1-12.5 volts after driving. Alternator is anywhere from 14.3 volts to 15.8 volts.

 

I'm sorry to hear it is still causing issues. Two things come to mind, but I may be way off:
1) low resting battery voltage + poor idle with accessories tells me there is a drain on the system somewhere. Obviously the engine needs power to fire injectors and ignition coils. Pulling power to the accessories, and still trying to do basic engine tasks with a power drain could cause your symptoms. Likewise, the alternator should be powering the system and charging the battery while the car is running. You may see high voltage from the alternator, but it may not be making it from the alternator to battery, from battery to PSDB and from PSDB to fuse box. (Honest conjecture at this point)

2) your new symptom with the rotary shifter leads me to believe that something leaked or was spilled on the center console. There is another post somewhere about similar symptoms. Since the EPB switch is co-located, maybe it is also grounding out and causing the fault. The EPB switch and rotary shifter may be the source of your voltage loss.

 

Nothing was spilled on the console, it was merely an example of the random glitches the car is experiencing.

After a charge overnight on the CTEK, the battery is around 13.5 volts. After a drive for perhaps 30-60 minutes and then letting the car sit for a bit, the battery voltage reads in the low twelves, consistently every time. Car starts up fine every time since I replaced the battery as the previous one would no longer hold a charge.

I have no idea if any of these issues are somehow related to the several years of battery replacements and BMS replacement but I spoke with a JLR tech who thought perhaps the issue was related to the electrics and a current draw, maybe a ground issue, alternator or even BMS.

I do agree with you about the electrical load and this is something I have brought up several times to 2 dealers over the last 2 years but to date none could identify the cause of the rough idle. From the beginning I had suggested perhaps there was too much current draw straining the systems but nothing related to that was ever sorted.

I've booked an appt for the week of the 25th at the main dealer as I have exhausted my abilities at this point.

 

Brought the truck to the main dealer, unfortunately earlier this month their management, service advisors and senior technicians all walked out so dealing with all new staff who don't realize or care I have been a client for 20 years.

Technician charged a ridiculous fee to run SDD and tell me the exact same thing I already knew, tons of repeated lost communication on high speed canbus DTCs which I had already told him before I left it in their care, in fact I advised them of the full details of everything that has been going on and what I have done to trouble shoot. His answer was he had no idea why and no idea how to troubleshoot. Apparently I know more about SDD and Land Rovers than their own technician.

 

They gave up trying to diagnose and advised they could open a ticket with Land Rover for one of their field engineers to have a look abut that would cost a further $700 with no guarantees of anything. I reiterated they had done nothing but repeat my own diagnosis and so was not charged anything.

For a couple of days I monitored voltage from the alternator and watch it spike as high as 16 volts and then drop and stay at around 11 volts. Also noted turning on heated windscreen, all seat heaters, AC and fan at max and other electrics would subtractivly lower the alternator voltage so I went with the theory I have had for a couple of years and overnight a new Denso DAN1112 replacement and installed it today.

The immediate difference noticed was no matter how many things were turned on and running, the engine ran as smoothly as ever. Also watched alternator voltage and it never fell below 14 volts and never went above 14.5 volts, even with high RPMs, so definitely a difference there and after 30 minutes, the voltage on the main battery increased rather than decreased. May be too soon to tell, but so far seems to be an improvement.

 

Fingers crossed!

towards your other note; if the alternator truly fixes it, and the dealer could not diagnose a faulty alternator, maybe they should not be open any longer. Dramatic, but at the very least maybe some additional diagnostic training is in order.

 

Yes, the original alternator was putting out voltage as high as 16+ to 17+ volts then would drop and sit at 11 volts day after day. Now with the new alternator, it is sitting consistently between 14-14.5 volts AND the main battery is now holding charge above 13 volts, no longer dropping to the low 12s. Only 2 days so far the conclusion is definitely there was an issue with the original alternator. I suggested to the main dealer several times about the erratic voltage output so I'm surprised they didn't come to any conclusion with that. Certainly saved a ton doing it myself.

By the way they did suggest the ECO battery could be the cause of the CAN bus issues and that I needed to have it replaced before they could proceed with any further diagnosis. I told them the battery had been flat for over 2 years without issue and have seen many online posts regarding defeating this feature by either leaving a flat battery in place OR disconnecting the battery without ill effect.