Mr Whippy
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| posted on 18/8/22 at 11:33 AM |
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Fiesta Alternator problems
Hi,
My Fiesta which had a recent new alternator is being a pain. All was well until the battery light came on out the blue and off course while on
holiday. I have a voltmeter in the car and I could see that it was not charging. So I pulled over and checked it and one of the connections on the
positive battery terminals was loose, so lose that it seems to have been arcing and had got so hot that the plastic protective cover had melted all
down the wire, lovely.
I cleaned up the terminals and tightened it all up. And all seemed well again, it was charging and the battery light went out. Then a few days ago the
battery light came on again but it is still charging at between 14.5 - 14.8volts. It's strange as the battery light comes on, I start the car and
the light goes out only to come on a second later and not go out till I turn off the engine.
I've checked all the terminals are tight and clean, checked all the fuses are fine, belt is new and tight and the battery is very good.
Any suggestions?? It's annoying as it was quite and expensive alternator and a sod to fit. It's a 2S6T10300DB btw.
Thanks in advance.
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obfripper
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| posted on 18/8/22 at 11:59 AM |
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The smart part of the alternator regulator is likely what has failed due to voltage spikes while the terminal was loose, have you got a ford specific
code reader to check the engine management for codes? An obd reader may not read the code as it is not emissions related, this also means the engine
warning lamp won't illuminate for the code being present either.
Dave
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Mr Whippy
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| posted on 18/8/22 at 02:15 PM |
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No I only have a cheapo reader although I do have a wireless OBD dongle I can try reading some codes from tonight.
Thanks
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nick205
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| posted on 18/8/22 at 03:06 PM |
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What was the cause of it needing a new alternator in the first place?
Any previous issues to report which might help identify a fault?
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adithorp
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| posted on 18/8/22 at 06:19 PM |
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OBPfripper is probably right (nothing new there) with regard to voltage spikes.
I'd be having a word with whoever serviced it. Checking the security of battery terminals is a pretty basic check that any numpty ought not to
miss.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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gremlin1234
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| posted on 18/8/22 at 07:44 PM |
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after reading any and all obd codes, I suggest you disconnect the battery overnight, so all the computers can reset. - yes literally turn it off and
on again, but it often does work!
and just to note, obfripper and adithorp are both incredibly good with all their advice.
[Edited on 18/8/22 by gremlin1234]
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Mr Whippy
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| posted on 19/8/22 at 06:00 PM |
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quote:
Originally posted by adithorp
OBPfripper is probably right (nothing new there) with regard to voltage spikes.
I'd be having a word with whoever serviced it. Checking the security of battery terminals is a pretty basic check that any numpty ought not to
miss.
I've already given myself a damn good telling off!
The original alt had shot bearings. I've tried clearing the codes, nothings working, think its knackered... 
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obfripper
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| posted on 19/8/22 at 06:14 PM |
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You could replace the regulator rather than replacing the whole unit, i would guess at probably £20-40 to replace with a decent quality one, and you
may need to get the soldering iron out for some internal connections.
A866X50372 should be the original regulator part number, have a look at some pics online and compare with yours to be sure.
As it is otherwise charging ok, i see no reason for other damage to the alternator.
You could check for any ac ripple using the ac setting of your meter, check from the +b terminal of the alternator to the casing, you want to see less
than 0.5v once the meter settles down (the initial dc connection will show as ac for a few seconds). Above this would indicate a diode fault, they
should be tolerant of at least 50v but is no guarantee.
Dave
[Edited on 19/8/22 by obfripper]
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gremlin1234
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| posted on 19/8/22 at 07:46 PM |
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quote:
Originally posted by obfripper
You could replace the regulator rather than replacing the whole unit, i would guess at probably £20-40 to replace with a decent quality one, and you
may need to get the soldering iron out for some internal connections.
A866X50372 should be the original regulator part number, have a look at some pics online and compare with yours to be sure.
As it is otherwise charging ok, i see no reason for other damage to the alternator.
You could check for any ac ripple using the ac setting of your meter, check from the +b terminal of the alternator to the casing, you want to see less
than 0.5v once the meter settles down (the initial dc connection will show as ac for a few seconds). Above this would indicate a diode fault, they
should be tolerant of at least 50v but is no guarantee.
Dave
[Edited on 19/8/22 by obfripper]
or if he still has the one with the failed bearings, he could use that for parts.
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