Battery Light on Dashboard - E46 330ci
Discussion
Hi Folks
Battery light came on this morning on my E46. Had a bit of a panic so pulled over and lifted the bonnet, all looked well, connections to battery fine. Alternator belt (a wee bit swishy sounding) but otherwise fine. Getting a slight squeak from one of the belt tensioners but again all working.
Decided to go to local BMW dealer. One of the service guys had a look and advised me that they would have to carry out tests to diagnose what the problem is, hour's labour starts at £106.60.
Drove car back to work, still have dashboard light but everything is working fine. Have started the car several times since and starts fine.
Obviously I need to get this checked out, but wondered if any of you had any experience of fault diagnosis when battery light shows?
I need to drive to the airport in a couple of days time and don't want to get stranded but on the other hand this could be a mild problem that I can sort on my return.
Battery light came on this morning on my E46. Had a bit of a panic so pulled over and lifted the bonnet, all looked well, connections to battery fine. Alternator belt (a wee bit swishy sounding) but otherwise fine. Getting a slight squeak from one of the belt tensioners but again all working.
Decided to go to local BMW dealer. One of the service guys had a look and advised me that they would have to carry out tests to diagnose what the problem is, hour's labour starts at £106.60.
Drove car back to work, still have dashboard light but everything is working fine. Have started the car several times since and starts fine.
Obviously I need to get this checked out, but wondered if any of you had any experience of fault diagnosis when battery light shows?
I need to drive to the airport in a couple of days time and don't want to get stranded but on the other hand this could be a mild problem that I can sort on my return.
Mine came on when an electrical item was switched on, wipers, rear screen, xenons.
Changed the belts (they were 4 years old anyway) and the problem persisted.
Internet diagnosis led to a failing alternator.
Measure the voltage across the battery terminals while the car is running. It should be around 14.1v, mine was much lower meaning the alternator was faulty, not the battery.
Changed the belts (they were 4 years old anyway) and the problem persisted.
Internet diagnosis led to a failing alternator.
Measure the voltage across the battery terminals while the car is running. It should be around 14.1v, mine was much lower meaning the alternator was faulty, not the battery.
The exact same thing happened to me a couple of weeks ago and it turned out to be the alternator.
I think the water pump is driven off the same belt as the alternator so if you carried on driving and it didn't overheat then I'd say the belt tension is fine. If the electrics still work and it starts then I'd guess the battery is holding charge - although it will be discharging each time you start it. So you should test your alternator...
You can do this with a multimeter across the battery terminals, or use the hidden menu on the on board diagnostic menu (google e46 OBC hidden menu and I think there's a good video on youtube) to get the battery voltage - menu 9. BEFORE you start the engine the battery should read 12V but when you start the engine this should rise to about 14V to indicate that the alternator is working and is charging the battery. Mine read 11V and it dropped slighty when I started the engine so it was the alternator. There's also a slight chance that there is a lose connection somewhere between the battery in the boot and the alternator under the bonnet and you can check this with a multimeter - if so then the reading across the battery should be the same as the reading you get from the red wire at the back of the alternator with the engine off.
If you want to change it yourself it's a pretty easy couple of hours work and the part cost me £140 with trade in of the old one. BMW quoted me £440 for the part alone...
Anyway, best get it checked out before you drive much further - spark ignition cars don't go very far without a working/charging battery!
I think the water pump is driven off the same belt as the alternator so if you carried on driving and it didn't overheat then I'd say the belt tension is fine. If the electrics still work and it starts then I'd guess the battery is holding charge - although it will be discharging each time you start it. So you should test your alternator...
You can do this with a multimeter across the battery terminals, or use the hidden menu on the on board diagnostic menu (google e46 OBC hidden menu and I think there's a good video on youtube) to get the battery voltage - menu 9. BEFORE you start the engine the battery should read 12V but when you start the engine this should rise to about 14V to indicate that the alternator is working and is charging the battery. Mine read 11V and it dropped slighty when I started the engine so it was the alternator. There's also a slight chance that there is a lose connection somewhere between the battery in the boot and the alternator under the bonnet and you can check this with a multimeter - if so then the reading across the battery should be the same as the reading you get from the red wire at the back of the alternator with the engine off.
If you want to change it yourself it's a pretty easy couple of hours work and the part cost me £140 with trade in of the old one. BMW quoted me £440 for the part alone...
Anyway, best get it checked out before you drive much further - spark ignition cars don't go very far without a working/charging battery!
My BMW 325i - year 2002, battery light comes on in the morning, when I first start driving. It's winter here in the Cape (Cape Town). Although the car keeps moving without problems, when I pull over and let the engine warm up a bit, then I can proceed without the light showing again. I took into BMW for a check and they said I need a new battery and alternator. However, I just took the car for an independent check and the battery checks out just fine "Good Battery" 12,59V, and Starter Test "Normal". Charging is at 13,94V and comes in as normal. As my car now has over 200,000 klms on the engine, could it be that the battery light is just a warning that it's an old lady now, and needs warming in winter weather before moving off, as although quite cold, we certainly don't have the kind of winters experienced in northern climates. Once the engine is warmed (a couple of minutes) the car works just fine, and I have no further problems. My alternator was changed three years ago. Not sure when the battery was last changed. Changing the battery and the alternator would cost roughly a thousand pounds, and I'm wondering if I'm getting the right advice from BMW, in view of the independent battery test. Should I get the alternator checked out independently also, because if the battery is charging okay, wouldn't that signal that the alternator is okay too? And if the alternator is faulty, should I get BMW to fit another, or can that be done anywhere, because it sure seems a lot cheaper to have other repair places replace this part.
Mido1311 said:
I have e46 318ci and the battery light came on on the dash then i charged my battery and its still there
Disappear only when i rev to 5 RPM
Is it the Alternator ?
I checked the belts they're all tight
Get a multimeter and check the battery; needs to be c12.4v with engine off, c14.4v with the engine runningDisappear only when i rev to 5 RPM
Is it the Alternator ?
I checked the belts they're all tight
Any less and you've a failed/failing battery and/or a duff alternator
If you're not wanting to do this, take it to a decent garage and ask them to check; think Halfords offer a free battery test too
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