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2012 Audi A7 3.0t had a alternator not charging battery warning . Replaced battery and alternator and still not charging. P1B0100 alternator electrical fault
Just last week I had a Ford Fiesta (Petrol 2009) with a charging fault, SMART CHARGE using a PWM signal for communication with ECU.
With a scope I proved that the ECU & Wiring was fine but the Signal was being corrupted / pulled down by the Alternator. Also tapping the alternator with a hammer would bring it back to life for a while.
Bought a "NEW" unit £240.00 - Same - Not charging.
Got the original tested and rebuilt by a trusted friend - same - Not Charging - £100.00
Voltage drop the B+ cable and the alternator case. If I remember right, I think the main block ground cable comes off when you replace this alternator.
I *think* the single wire field connection is a LIN with the battery module. If you disconnect the field connector, does the alternator start charging? With the connector unplugged and the key on, what voltage do you find at the violet/white wire?
If the B+ and alternator case don't have excessive voltage drops, and the LIN is good all the way out to the alternator, and the belt isn't slipping, then the alternator has everything it needs to work. Get another alternator.
