Technical punto mk1 battery light on

[flisko]

punto 1994 55s

car starts normally but battery light stays on, when i start driving it turns off in a while is this alternator fault or? car battery is good

 

[Noddy]

If the alternator belt isnt loose then I would say that the alternator has a fault.

 

[(CZ)enda]

Measure the voltage, IIRC, the procedure is described in detail in Haynes Book of Lies.
Possibly worn brushes.

 

[fingers99]

Alternatively the smaller of the two cables to the alternator has become damaged or detached.

 

[blu73]

as above. Check voltage when running and not running, check/clean all connections, check belt tension.

 

[flisko]

the light has gone away on its on, gonna try some of the stuff described above

 

[flisko]

this is what was happening -> https://drive.google.com/file/d/0B6X7mqLVnIypcmhsSjFQM2JXSjA

also is fiat punto mk2 alternator same as on mk1?

 

[Noddy]

The warning light works by looking for voltage, above a set voltage the light goes out, below it it comes on. At low revs your alternator isnt putting out enough volts to turn the light off. If you havnt checked the belt tension, then do that as the belt may be slipping. Otherwise a replacement is needed. I believe the alternators on the Mk2s are the same But I dont know about ouput etc. Best bet would be a local scrapyard and get one from a low spec Mk1.

 

[flisko]

The warning light works by looking for voltage, above a set voltage the light goes out, below it it comes on. At low revs your alternator isnt putting out enough volts to turn the light off. If you havnt checked the belt tension, then do that as the belt may be slipping. Otherwise a replacement is needed. I believe the alternators on the Mk2s are the same But I dont know about ouput etc. Best bet would be a local scrapyard and get one from a low spec Mk1.

checked alternator belt tension and it seems to be tight enough, measured car battery voltage while car was turned on and it was around 14V, but when i turned everything else on- lights, heating, radio... the voltage dropped to around 13.4V, was looking around and other people had somewhere around 13.7V -14V, so it may appear alternator is ****?

 

[varesecrazy]

checked alternator belt tension and it seems to be tight enough, measured car battery voltage while car was turned on and it was around 14V, but when i turned everything else on- lights, heating, radio... the voltage dropped to around 13.4V, was looking around and other people had somewhere around 13.7V -14V, so it may appear alternator is ****?

does the battery light GLOW slightly ( easiest to see at night!),

I've had that before and it's the Regulator on the back of the alternator, never cause an issue - as it's only cutting out the last @5% of the charge.. as you've found the car will still start fine

Charlie

 

[Ziggy122]

checked alternator belt tension and it seems to be tight enough, measured car battery voltage while car was turned on and it was around 14V, but when i turned everything else on- lights, heating, radio... the voltage dropped to around 13.4V, was looking around and other people had somewhere around 13.7V -14V, so it may appear alternator is ****?

Nope thats fine

You want
Engine off overnight 12.3 - 12.6v idearly
Engine Running 14v+ (i'd be happy for a flat battery to be running at 13.8v as it charges up moving to 14v later)
Engine idle + loaded electrically = 13v+
engine speed 2500rpm + loaded electrically = Higher then the previous result

ziggy

 

[flisko]

so, lower voltage on the alternator/battery does not affect car performance in any way?

 

[flisko]

yea car has just shut itself down in the middle of driving, it started again via jumper cables but doesnt want to start on its on, probably means that alternator has finally died, gonna take one from mk2 punto and put it in

 

[flisko]

yea car has just shut itself down in the middle of driving, it started again via jumper cables but doesnt want to start on its on, probably means that alternator has finally died, gonna take one from mk2 punto and put it in

was told that puntos from 93 - 2003 have same alternators

 

[flisko]

this is what was happening -> https://drive.google.com/file/d/0B6X7mqLVnIypcmhsSjFQM2JXSjA

also is fiat punto mk2 alternator same as on mk1?

final conclusion

if you got same as in above video, your alternator brushes are probably gone as were mine, i replaced whole voltage regulator which contains brushes, but you can only change brushes or whole alternator, i took voltage regulator from mk2 punto alternator

note: mk2 punto alternator caused all the lights to constantly flash when fitted to mk1, thats why voltage regulator was taken from it and placed in mk1 alternator

strangely mk1 alternator works normally on mk2 but not other way around

https://www.fiatforum.com/punto-mk2-2b-guides/284983-changing-fiat-punto-1-2-8v-mk2-alternator.html

 

[randy8891]

Hi Flisko,

Brushes are just one side of it. Other is the diode plate which sits at the back of the alternator. In my case the brushes and the voltage regulator was perfect and the issue was in the diode plate. One diode had completely burnt out resulting a false DC conversion and that was why I had my battery light lit as same as in your video. Since I couldn't find a diode plate, I had to replace my alternator to a reconditioned one. Now it works perfectly.
Anyway you made me find what was wrong in mine. Thanks mate. !

 

[flisko]

Hi Flisko,

Brushes are just one side of it. Other is the diode plate which sits at the back of the alternator. In my case the brushes and the voltage regulator was perfect and the issue was in the diode plate. One diode had completely burnt out resulting a false DC conversion and that was why I had my battery light lit as same as in your video. Since I couldn't find a diode plate, I had to replace my alternator to a reconditioned one. Now it works perfectly.
Anyway you made me find what was wrong in mine. Thanks mate. !

good job