alternator failing symptoms???

[d1mkaz]

when I turn ignition key to start the car all the lights on dash light up, as it should be, and when engine starts they go off, but sometimes they don't , when I press accelerator just a little bit, they go off. It was not happening before, and it does not happens very often, but I just want to be sure that everything is fine.
any suggestions? how can I check if the alternator failing, or may be it's just cold weather?

[eltel]

it sounds like a fault with the charging system.. could be the regultor pack that bolts onto the back of the alternator or faulty diodes in the circuit.

can you test the charging output with a multimeter??

[Duke137]

Brianmooore's input required here.

[beemerbird]

How does your car run? Mine often shows the symptoms you are describing but it drives spot-on.

[e30mazm3]

Do you mean all the red lights or just the battery light? If its all the red lights then its probably just a very lumpy/low idle which will bring them on as if it is going to stall.

For example the oil light will be on because the engine isnt running fast enough for the oil pump to prime to the right pressure

The battery light will come on also as the alternator isnt spinning fast enough to create enough charge.

These will come on if your idling at 500 revs or less

The brake pad warning red light has proabably been on since day one. ignore it

What engine?

[beemerbird]

Ah, you are talking about different lights. Oops

[Brianmoooore]

Several of the cluster warning lights have a 'test' function that operates when the ignition is switched on, and go out when a sufficiently high voltage is detected from the alternator D+ terminal (blue wire).
This 'fault' could be caused by the alternator, the cluster, or because the engine idle is too low.
If this is the only problem with the car, I wouldn't worry about it for now.

[eltel]

clarify which lights are on please..i assumed from the title it was the charging light but e30maz may have the answer

[Barton]

i have the same thing on my car its 3 lights together in a row

battery, oil and another one

its happened before and after my engine swap using different alternators, different looms and different ecu's

[Ajsingh]

My car has done this ever since iv had it. Its never caused any issues but only happens sometimes.. A quick blip of the throttle and they go out..

Iv given up worrying about it.. I also have a friend whose E30 M3 does the same thing. He has even had the alternator apart and replaced everything internally and it still does it. He too has now given up worrying

[Barton]

i might just check the connections at the back of the clocks

[d1mkaz]

How does your car run? Mine often shows the symptoms you are describing but it drives spot-on.

drives as a charm, no problem whatsoever, just this little "nonsense " occasionally

[d1mkaz]

Do you mean all the red lights or just the battery light? If its all the red lights then its probably just a very lumpy/low idle which will bring them on as if it is going to stall.

For example the oil light will be on because the engine isnt running fast enough for the oil pump to prime to the right pressure

The battery light will come on also as the alternator isnt spinning fast enough to create enough charge.

These will come on if your idling at 500 revs or less

The brake pad warning red light has proabably been on since day one. ignore it

What engine?

sorry, it's all usual red lights on the bottom of the dash (battery, oil, breaks), they always light up when starting and go off after engine start, the idle is 100% the same at all starts (above 500), it's just sometimes they would not want to go off, only after a little touch on accelerator pedal. I never had it before. Started may be couple weeks ago, and minding that I drive every day, it happened 3-4 times.

[d1mkaz]

Several of the cluster warning lights have a 'test' function that operates when the ignition is switched on, and go out when a sufficiently high voltage is detected from the alternator D+ terminal (blue wire).
This 'fault' could be caused by the alternator, the cluster, or because the engine idle is too low.
If this is the only problem with the car, I wouldn't worry about it for now.

thank you, I'll try to not to

[beemerbird]

Yes, don't worry about this. Mine does it more often than it doesn't.