alternator

yorkshire1

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i know this isnt specifically merc but I presume its common to a lot of alternators

I have a daughter with an Audi A3 2003 with charging fault ....ignition on no battery light and no power at what I assume is excite wire at alternator (2 wire plug) and once started no power output from alternator.

Am I ok giving the excite terminal 12V to kick the alternator in to test its function and is the second wire in the 2 pin plug an earth thatll need connecting to test also,

Assuming the above tests out ok is the battery light excite wire circuit likely to be mired in electronic wizardry, many thanks
 

mattkh

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Hi
If the wire connections look OK, I would try a new voltage regulator.
Any chance of a photo of the back of the alternator.
 
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yorkshire1

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photo

Hi matt pic Valeo hooking up earth and 12volt excite feed still no joy
 

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yorkshire1

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charging

have now changed alternator and its charging, however with ignition on there is still no battery light and no excite 12V feed to alternator which makes me wonder why its charging,and how this charging system works, will have to keep an eye on it to make sure it doesnt overcharge
 

Miffy

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Do not modern Alternators self excite? Dynamo's require an excite feed
 

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Do not modern Alternators self excite? Dynamo's require an excite feed

No they all need excitement :) in most cases the thin exciter wire goes open circuit
 

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