Question about 2003 Honda S2000

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Honda S2000 engine installed in kit car. How do I wire alternator

I am using a Ford wiring loom and find that the Honda alternator has 4 "control" wires where as the Ford altrnator has only 2.
The Honda alternator plug cables have the following code:-
White /red
White /green
Black/yellow +12v

Can you inform me how I wire in the Honda alternator?

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Unfortunately the Honda alternator is regulated by the ECU, which allows the ECU to intelligently reduce alternator engine loading to improve fuel consumption. The intelligent system uses an electrical load detector (ELD) located near the battery to control the alternator output voltage. A two wire alternator has an inbuilt regulator that will always generate the required charging voltage. When a battery is fully charged and the electrical loading is low there is no need for generating the charging voltage, in this situation the honda alternator will reduce the output voltage to reduce engine loading, hence improved fuel economy.

Posted on Jun 20, 2009

  • sion rich Jul 01, 2016

    Update: although the ECU regulates the alternator voltage it will work fine on its own. All you need to do is connect switched 12V to the black/yellow wire. The white/blue cable can be used to give you your normal dash battery light indicator, if the alternator is not generating it will provide an earth.



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