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Discussion Starter #1
Hello guys someone please help,

It's started when the xenon bulb failed then I get an error that battery is low I change the bulb, the car used to start like that:

1. press break and start the car wouldn't not start just whippers working and no dash lights,
2. after like one minute you start the car and it start normal dash lights come on then you turn off the car start again everything is okay, but I get tons of errors which does not make sense

One day I parked the car went to the shop come back and the car won’t start at all now I have all the same symptoms just the car instead of starting just cranks and nothing else,

Anyone knows what is the problem could be? I thought maybe ECU or some connection to the car not giving the power to ECU?

Also if I re-plug the battery off and on then the dash is working giving a lot of errors, and car won’t start

It's not the battery as I replace it from my other BMW f10 its work fine

VIDEO OF THE CAR:

video 1509986432 - Sendvid
 

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Lots of errors is a low battery sign, was the replacement battery of similar vintage?
Does an overnight charge make the problems go away?
 

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Your clock was resent on the iDrive, that means dead battery.

Replacing a battery from another car for a quick test will not achieve anything as a battery has to be registered. If it is not, it will not make any difference as car will think its still the old battery
 

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Discussion Starter #4
I put back my old battery and the battery was exactly the same as last one I think maybe module on the battery failed ?
 

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I repeat again, swapping battery will not work unless you reset the battery and let the car now something different has been put. Its done via coding (can be done with Carly). Even if you put a BRAND NEW battery in, the car wouldn't know it hence none of the errors would vanish.

Also, if your old batter has a weak cell in it, you can charge it all you want, its still a dud and needs to be replaced.
 

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Discussion Starter #8
The battery is completly fine as I put in my brother bmw f10 and he used it and it's work completly fine I am saying once again it's not a battery issue it's something else and the battery is identical with mine
 

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Next place to look then is the voltage regulator although the fact that it won't start suggests looking elsewhere. I'd start looking for water ingress or possibly a bad earth strap. I'm not sure how bad the f10s are for getting wet. Realistically you will need to get some live diags running. These things always throw a bunch of errors when the battery gets disconnected so I expect a lot of what was on the dash was just spurious junk.

Do f10s use an IBS cable or have BMW seen sense by now?
 

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The battery is completly fine as I put in my brother bmw f10 and he used it and it's work completly fine I am saying once again it's not a battery issue it's something else and the battery is identical with mine
You genuinely don't get what im saying and principle of how an F10 recognizes a battery :shifty:

Tell you what. Whereabouts in London are you? I can read any error codes with Carly
 

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Discussion Starter #12
Next place to look then is the voltage regulator although the fact that it won't start suggests looking elsewhere. I'd start looking for water ingress or possibly a bad earth strap. I'm not sure how bad the f10s are for getting wet. Realistically you will need to get some live diags running. These things always throw a bunch of errors when the battery gets disconnected so I expect a lot of what was on the dash was just spurious junk.

Do f10s use an IBS cable or have BMW seen sense by now?
can it be negative cable ? damaged ?
 

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The long and the short of it (no pun intended) is that BMWs are very picky about the quality of the electrical supply. It doesn't take much to throw them off. The older models certainly had problems with the IBS cable. The easy test is just to disconnect it. If the faults clear then there's the problem. In essence when they go bad they end up giving bad data to the controllers and potentially causing an assortment of voltage/current supply problems. In relation to the point Jak is making, one of the ways the car knows what battery its got, what load the battery can sustain, how much charging current to supply and so on is via the IBS cable. If its hosed then all that good information is lost. The coding gives the car a baseline for what to expect so it can function without the IBS if called upon to do so.

If you have a bad earth then you'll have a lot of noise on the supply, probably combined with limitations on current supply.

EOD this is all just guesswork without diagnostics. The advantage of pulling the IBS cable is that its easy and costs nothing to try. If it doesn't help, move on. You can warm yourself up to the prospects of fighting faulty immobilisers, bad ECUs and so on afterwards.
Worth noting that ECUs themselves rarely go bad. They are an intrinsically robust design so don't automatically assume the worst. Do the basics like checking all the fuses, reseating connectors etc. Stick a meter across the battery with it disconnected, then with it connected. Look for excessive voltage drops. You are looking for around 12.6V on an isolated lead/acid battery. Depending on what is active when the car is in standby it should still be 12v+ when connected but with the ignition off. All of this will show up with a good diag tool.
 
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