Flashing battery warning light....

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1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 81

  Z3 roadster 2.0

Flashing battery warning light....

Post by 1963paul » Thu 22 Dec, 2016 08:05

Hi all...
Just had the camshaft and exhaust sensor replaced to cure a "starting and stalling issue when hot"...that's all ok now, car runs like a dream...but
now the battery light on the dashboard flickers on and off very occasionally, just for a second or two, happened twice yesterday morning on the way to work, about a 15 mile trip, didn't happen on the way home, but a couple of times this morning. Popped in Halfords last night on the way home to get the battery and charging circuit tested, all ok, no issues at all....would the mechanic have to disconnect anything, multi plug etc to change any of the sensors?...just wondering if I mighty have a lose connection or something.
I haven't looked myself as its too dark when I get back to my car.

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 567

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Flashing battery warning light....

Post by colb » Thu 22 Dec, 2016 09:30

Found this answer to your question elsewhere on the web which points to the charging circuit being at fault.

The problem is in the charging system, there are a few things that you can check yourself before taking it to a garage if you don't feel that you are capable of doing it yourself. when it is dark start the engine and let it idle with no lights on so the dashboard is dark and see if the battery warning light is glowing faintly, leave it doing this for a while and see if it happens on it's own, then turn on the heater blower and see if the light glows brighter. do the same with the rear window heater, stereo, wipers.lastly the lights starting with the side lights working upto main beam and fogs. if the light comes on whilst do this and it gets worse the more things you switch on then the problem is the alternator not putting enough charge back into the battery this could be due to the brushes being worn especialy if the car is of a v reg or older. this is a new alternator that is required. if the light comes on with it just idling with nothing on and it dose it as soon as you start the car then it could be the fan belt or a loose wire connection on the alternator or the battery terminals are loose. to check the fan belt tension make sure the engine is switched off and locate the longest side of the fan belt and twist it, if you can twist it more than a quarter of a twist it will need tightening, if not then it is not the fan belton the alternator there should be a thick wire and 1 maybe 2 thin wires, the thick wire goes from the battery to the alternator this should be tight. if it has 1 thin wire this goes to the dashboard to the battery warning light this should be connected with a terminal connector and should be tight, if it has 2 wires one will go back onto the alternator and the other is the same as the 1 wire type check both wires to see that they are tight if so then it still could be a loose wire so check the battery terminals to see if they can be moved if not then it is likely the diode pack on the alternator which is a replacement alternator if any of the wires are loose then it could be causing a short circuit that as the engine is running the vibrations of it can be causing the connection to be temporary disrupted causing the light to flash on and off tighting the connections will sort it, if your battery is over 4 years old then think about changing it when starting becomes difficultas the life of a battery is about 4 years if you replace the battery then go for a heavy duty one it will cost a bit more but it gives you better quality when starting as it has a longer amount of time for starting than a standard one also ensure that youget one of the right ampage for your car if your car is a diesel then it a more powerfull battery than a petrol of the same engine size is required. hope that this helps you all the best
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 81

  Z3 roadster 2.0

Re: Flashing battery warning light....

Post by 1963paul » Thu 22 Dec, 2016 09:46

Wow, thankyou for that very comprehensive reply!...lots to read and digest.... :rtm:
I did have the charging circuit and battery tested last night, all ok, so I'm thinking lose wire/connection plug, I'm off tomorrow, so a look under the bonnet in daylight would be the 1st thing....just hoping someone would say "ah yes, the multi plug under the ......always gets a bit dodgy after you change that particular sensor..."

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 567

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Flashing battery warning light....

Post by colb » Thu 22 Dec, 2016 09:55

When I had charging issues, I bought a small battery meter that plugs in to the cig lighter socket so I could see what the charging rate was as after driving at night with lights on the car was dead with a flat battery next day. Using the meter I found the alternator was not putting out a full charge, could have done the same using a multi meter on the battery but the plug in unit was a useful accessory to have.
http://www.ebay.co.uk/itm/LED-Display-C ... Swj85YLryf

Did think about putting a permanent Battery Guage in but no space in the car dash to fit one, shame BMW didn't fit one.

The sensors you had changed shouldn't have anything to do with the fault you now have with the battery warning light, they wouldn't have had to disconnect anything other that the sensors themselves. Probably just a coincidence that you have this happening now. If all the wires and connectors are tight on the alternator I would suspect dodgy brushes in the alternator or the diode pack in it starting to breakdown. Battery meter will show you what its performing like, you should see something like 14v when engine running and its charging ok. See what its doing when the warning light flashes, if its the alternator you should see it drop the voltage as the warning light lights up.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 81

  Z3 roadster 2.0

Re: Flashing battery warning light....

Post by 1963paul » Thu 22 Dec, 2016 10:39

Thanks again, just ordered the plug-in meter, looks to be a handy gizmo!.

therealdb1
Joined: Tue 25 Jun, 2013 22:47
Posts: 232

  Z3 roadster 2.0

Re: Flashing battery warning light....

Post by therealdb1 » Thu 22 Dec, 2016 13:36

Hi Paul, something that these cars seem to be prone to, although I have no idea why, is that the negative lead at the battery itself can become loose.
It has happened on my car twice although as far as I know a flashing battery warning light is not a symptom. On mine you just get nothing when you turn the key in the ignition and then after a couple of tries it will start. Tighten the connection and it lasts another couple of years before it does it again.
A simple check you can do yourself in the daylight. I know that someone else has checked the battery and charging circuit but they probably hooked up huge crocodile clips and may not have checked that the cable terminals are secure on the battery posts.
It does sound to me like you may either have alternator brushes on the way out or a regulator which is misbehaving.

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2115

  Z3 roadster 1.9

Re: Flashing battery warning light....

Post by Del » Thu 22 Dec, 2016 13:39

Personally, with these "flickering" or "dimly flickering" warning light issues, I would suspect either the alternator or the auxiliary belt driving the alternator. As you say, I would check and clean the battery terminals as they may have been disconnected (as a sensible precaution) when the new sensor was fitted. Under the rubber cover, the alternator simply has a nut holding the cable ring to a threaded shaft - again no harm in checking/cleaning this. If you are happy that the alternator/battery are fine I wonder if the auxiliary belt is cracked/glazed (with age) and slipping - or a bit slack due to the failing tensioner - although I would expect some noise from a failing tensioner. :shrug

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 81

  Z3 roadster 2.0

Re: Flashing battery warning light....

Post by 1963paul » Fri 23 Dec, 2016 01:32

Thanks all for the replays and suggestions, weather permitting, I'll have a look tomorrow.

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 81

  Z3 roadster 2.0

Re: Flashing battery warning light....

Post by 1963paul » Fri 23 Dec, 2016 10:42

Well, I had a look, it's a bit tight under there to see what's what, but a electrical plug on the generator did "click" when I pushed it home, so might have done something, time will tell.

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colb
Joined: Sat 05 May, 2012 23:46
Posts: 567

  Z3 roadster 1.8 TU
Location: Newport South Wales UK

Re: Flashing battery warning light....

Post by colb » Fri 23 Dec, 2016 11:44

That sounds hopeful, check what the alternator is putting out when you get your volt meter it may have been a dodgy connection with the plug not fully home. Keep your eye on the warning light as well to see if it solved that.
Colb
1999 BMW 1.8 Z3
1998 Honda Deauville NT650V

bertiejaffa
Joined: Fri 26 Jul, 2013 10:28
Posts: 1715

  M roadster S50
Location: Manchester

Re: Flashing battery warning light....

Post by bertiejaffa » Mon 26 Dec, 2016 22:32

therealdb1 wrote:Hi Paul, something that these cars seem to be prone to, although I have no idea why, is that the negative lead at the battery itself can become loose.
.

It happened to my 2.0l as well, very odd. I too dont remember the light flickering but the symptom was that it wouldn't start sometimes. I check mine every so often now as a general course of action
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1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 81

  Z3 roadster 2.0

Re: Flashing battery warning light....

Post by 1963paul » Sat 07 Jan, 2017 00:53

Must have been the multi plug, since I pushed it home, it's been fine :D ( that's done it)!

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