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Chris_91132

HELP - 2012 F11 520D total electrical failure

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So this is a strange one.

 

Car has shown no warning messages or any unusual symptoms. It was used yesterday for a decent period of time.

 

This morning it is totally dead - there is no electrical power at all. I went to the car this morning and it was unlocked - was definitely locked yesterday evening with mirror folded in. There is no power for anything - handbrake light shows momentarily on dash when engine start button pressed. No power to tailgate.

 

I have tried to jump start it - this has absolutely no impact. The car is just dead. I have left the jumper vehicle running and connected for 10+ minutes to no avail. Still nothing - nothing electrical works even with the jumper connected.

 

So, what now? Any ideas please? Anyone else experienced this, or similar?

 

The battery is  the original, bu there have been no battery warnings, or signs of a change in starting behaviour. I have checked the both key fob batteries.

 

Utterly stumped :( 

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The only problem is I cannot get to it - cannot open the tailgate.

 

I could crawl in through the rear seats but I'm not doing that in this heat.

 

I suspect that it is not the battery though - in over 30 years of driving I have never had a battery failure like this. Apparently absolutely fine one moment and totally dead the next. And no impact when jump starting. This suggests to me that there is a cable/connector failure.

 

I am more inclined to believe that it is related/similar to the cases of total electrical failure that have occurred with other models. I have just taken out home start insurance so plan on making a call when the cover starts in a couple of days.

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It’ll be impossible to get to the battery from the rear seats as the load bed tilts up at the tailgate. 

 

It is a stretch that the battery has had an internal fatal short but I also thought the AGM batteries were far less prone to this due to the fibreglass insulators between cells. 

 

I’d be looking at the cable to the starter motor from the rear but that is a pain as you need to remove the underbelly covers. It could have broken at the starter motor which would be easier to check.

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51 minutes ago, Matthew Ashton said:

It’ll be impossible to get to the battery from the rear seats as the load bed tilts up at the tailgate. 

 

It is a stretch that the battery has had an internal fatal short but I also thought the AGM batteries were far less prone to this due to the fibreglass insulators between cells. 

 

I’d be looking at the cable to the starter motor from the rear but that is a pain as you need to remove the underbelly covers. It could have broken at the starter motor which would be easier to check.

 

But even with that cable not connected would I not stil' have something working in the car?

Plan at the moment is to get it recovered to Cotswold BMW, hopefully Saturday.

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Can't be a dead short as that would have brought down the donor vehicle but it should have been possible to jump start it.

 

Unless the jump leads you were using were too small. Jump starting depends a lot on the quality of the jump leads and the availability of power from the donor car. You want 25mm^2 jump leads for cranking a Diesel.

 

Or there is a loose main connection somewhere on the starter.

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this might sound odd, but did you try using your spare key? it might be your key is dead and is why nothing is working.  or potentially the antenna is not registering. Just another thought process to consider possibly. 

Edited by dj1233

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I had the same issue on my e91, turned put the negative cable to the battery wasnt as yoght as it shouk have been. Green flag tightened it up and hey presto. No new battery needed or anything.

Surely these power tailgates will open manually in the event of power failure??

Sent from my SM-G950F using Tapatalk

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Does anything like hazard warning lights work? These cars have a little explosive battery disconnector intended to cut anything heavy duty in the event of an accident and they have been known to fail. May tie in with doors being unlocked if the car thought there had been an accident. A bit out there I know but....

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1 hour ago, JCP said:

Does anything like hazard warning lights work? These cars have a little explosive battery disconnector intended to cut anything heavy duty in the event of an accident and they have been known to fail. May tie in with doors being unlocked if the car thought there had been an accident. A bit out there I know but....

 

Way out there but plausible - good idea.

Forgot all about that little gem but still screwed if you can’t get at the battery due to the electric catch on the tailgate. 

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There is no mechanical release (key) from outside is there in these cars any more is there?

 

If you can get in to the car, try the dash button for the tailgate opening might be just enough juice to pop it open. 

 

Failing that.

 

The bonnet opens mechanically and you can then put a donor car (as in jump start) across the jump start terminals which should then give you power to open the tailgate to get at your battery. 

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23 minutes ago, 535i Andrew said:

There is no mechanical release (key) from outside is there in these cars any more is there?

 

If you can get in to the car, try the dash button for the tailgate opening might be just enough juice to pop it open. 

 

Failing that.

 

The bonnet opens mechanically and you can then put a donor car (as in jump start) across the jump start terminals which should then give you power to open the tailgate to get at your battery. 

 

No key on the Fxx cars for the tailgate and the OP tried the jump start to no avail.

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Ah my bad re-read first post.

 

Odd that nothing worked when connected to a jumper. That points to something major if nothing at all worked. If the jump leads are too small it might prevent cranking but should be enough to get power to work ancillaries assuming jump leads are connected properly.

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The car is deader than a dead thing.

 

I have tried connecting a charger across the terminals under the bonnet for a few hours. Did nothing other than get the charger stupefying hot to the touch - it's a smart charger which interestingly didn't show any charging error codes.

 

My hope was to get just enough juice into the battery to pop the rear hatch window at least. Nothing. Zip. Nada.

 

I fear some glass may have to be broken......

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My Ctek smart charger does get fairly toasty when it is doing a deep charge on a battery I use in the garage as a 12V power source. The charger getting hot is a sign it's working proper hard to charge the battery, a badly depleted battery will take the best part of a day to recharge. A charger will only charge at a few amps.  Far less than any alternator output so will take a while. My Ctek charger output is rated at 5 amps. But yes a smart charger will stop working if it detects an error or problem in the battery.

 

Get it recovered to a decent garage professionally so that you can limit the damage.

 

Is it under any warranty? 

 

Do do you have AA, RAC, Green Flag etc?

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34 minutes ago, Chris_91132 said:

The car is deader than a dead thing.

 

I have tried connecting a charger across the terminals under the bonnet for a few hours. Did nothing other than get the charger stupefying hot to the touch - it's a smart charger which interestingly didn't show any charging error codes.

 

My hope was to get just enough juice into the battery to pop the rear hatch window at least. Nothing. Zip. Nada.

 

I fear some glass may have to be broken......

 

CTEK do an adapter that plugs into one of the 12v sockets in the car. If you have the 12v socket in the boot and one of these plugs attached to your smart charger,  while I don’t like the idea of injecting charge through the car’s internal wiring system, maybe this is a way of energising the fuse box in the car giving you just enough power to pop the tailgate or the glass hatch. 

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Quick update.

Called out our breakdown cover on Sunday. Guy tried a few things but no dice.

He thinks the battery is fine.

Car was recovered today to my local BMW agent (Cotswold) this morning. I believe they are going to look at it tomorrow.

I'll update this thread with what they find.

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Well I'd really like to be able to give a full account here, but....

 

Car was recovered to local BMW agent. Picked it up yesterday lunchtime.

And the outcome is....no fault found.

They disconnected and reconnected the battery and the car from that point on was absolutely fine.

They kept it for a few days hooked up to diagnostics kit to look at the battery drain and to try to identify the cause of the problem, but they have seen nothing that identifies or explains what happened.

 

So unfortunately my experience doesn't increase the pool of knowledge one jot.

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On the positive side (slight pun accepted) you now have your 5 back and working again. Annoying not having a definitive answer, but sometimes it's just one of those things...

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2 minutes ago, 535i Andrew said:

I think that is what is called "having one of those moments".

 

At least its back and working.

 

So the fix is leave it, disconnect the battery and reconnect it.

 

If you can get to the battery in the first place.

I did ask them how they managed to reach the battery but didn't get an answer - they wouldn't tell me what options they have....

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1 hour ago, Chris_91132 said:

 

If you can get to the battery in the first place.

I did ask them how they managed to reach the battery but didn't get an answer - they wouldn't tell me what options they have....

 

That’s shitty of them not to tell you! It is a flaw if you find yourself in that situation. In the US, and not sure if it still stands but they had an emergency release inside the boot to open the boot lid. Must be because of all the kidnappings :ph34r:.

 

 

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All BMW's have an emergency tailgate release on the inside. On most it's on the tailgate itself but on these, it's under the boot floor. Lift it up and look for a black cable with a blue hoop on the end. Yank that and the tailgate will open.

 

It sounds like a faulty battery. You can access it easily.

 

 

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