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Circuit Race Car Alternator Wiring Help

Practical Motorsport Wiring - Club Level

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Discussion and questions related to the course Practical Motorsport Wiring - Club Level

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Greetings to all.

First I want to thank HP Academy, thanks to you I already did my first engine and chassis wiring.

I would like you to help me with the wiring of the Honda k20 alternator.

Since it's a race car, I don't have the original ECU and I have doubts about how to connect the alternator wiring, it's the only thing I need to finish.

I read in many forums that the Honda k20 alternator works very well without the connection to the computer.

This alternator has 5 pins which are:

B = connects directly to the positive of the battery.

IG (BLK/YEL) = 12V switch.

C, FR, L = are the ones that go to the OEM PCM (Do they not connect?)

If so, and my real question is how should I connect the lamp so that the alternator charges.

I also read that you can put a resistor in line to simulate the lamp but I don't know where to put it.

Can someone tell me where I should put it? from which cable to which cable?

Attached Files

Do you care about the light and/or regulating to lower voltage? If no to both, all you need is the field (black/yellow) connected to 12v, everything else is superfluous.

I am not interested in regulating lower voltage but if I would like to have the light of the lamp or I would like to have the resistor on.

What I need to know is where or how to put the light or the resistance.

OK, but you know that you don't need the lamp for the alternator field and regulator to function, right?

No, i did not know.

It will not affect me at high RPM, if I don't put it?

Well, this is what I was asking earlier - I think there may be a language barrier so no worries.

If you're asking for a dead simple setup without the high/low voltage system all you need to do is run 12v to the field wire - black/yellow that will default the regulator to 14.2ish volts. You'd then leave the other wires disconnected.

You can also relatively easily force the regulator into its low power state using the white and green wire, but again, this isn't required.

Yes, the language thing is true, I am not an expert with English sometimes I use google translator but I understood you correctly. Thanks for the help David.

I would be wary of a direect 12V feed to the field windings - while I'm not familiar with that variation, the bulb resistance, or a separate resistor in-line, is usually needed to regulate the current and avoid burning out the voltage regulator.

Factory configuration is 12V to the field via black/yellow and the ignition switch. Leaving the rest of the wires disconnected defaults to high output, which generally hasn't posed a problem long term on the handful of K20s I've supported that don't have provisions for control.

We usually reply within 12hrs (often sooner)

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