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Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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Mercedes-Benz C230 Kompressor: 2004 benz c230 kompressor alternator/

Resolved Question:

2004 benz c230 kompressor alternator/ battery red light comes on & was not charging i replace the alternator , its charging now, but after 2 minute of eng running light comes on while charging at 14.22 volts
Submitted: 5 years ago.
Category: Mercedes
Expert:  Stan replied 5 years ago.

Diagnostics Engineer :

Some of the C-classes had alternators with smart interface to engine control unit. Their voltage regulators are able to send a signal out to engine control unit about the output state of alternator. When this output is not ok- engine control unit stores a fault code and sends a message to activate the warning.

Diagnostics Engineer :

At the same time there same generation C-classes with simple excitation wire.
If the alternators are mixed up- warning message will be triggered.
It seems that you got an alternator with unsuitable voltage regulator for your C-class.

Diagnostics Engineer :


Customer: What if I change the excitation wire position on the bosh alternator from pin one to pin two would the light go out
Diagnostics Engineer :

This will not make the alternator to communicate. Check with the supplier if they can offer the alternator with a smart communicating voltage regulator.

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