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Alternators on Honda powered cars.

224 Views 3 Replies 2 Participants Last post by  Kinversand
Hi All,

I need a bit of help please. I been suspecting a faulty alternator on my 600 for a while. I recently put a multimeter across it at, at idle it was only giving 12.5 volts. Surprisingly (for a Japanese engine) the alternator is a Bosch. I've tried to get it rebuilt, but it seems that parts or these have become scarce. However, that's not the reason for the post.

What I want to know is at what point during 600 production was the alternator wiring changed from what's shown in the 1996 circuit diagram?... I've had my car since early 2007, and the alternator loom hasn't been modified, but where the diagrams show the WR wire connected to the FR terminal, it's actually connected to the IG terminal, and where the charge light cable is shown connected to the L terminal, it's connected to FR. The BY cable missing completely!! Need help please!

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Sorry I cannot help you with your key question. Re your analysis that you have a problem, what voltage do you expect to have at idle - is 12.5 indicative of a fault? I'd be more inclined to ask what the volts go up to at 2000 or 4000rpm.
I think you'd be expecting something around 14.8V (depends on temperature). Are you completely happy with the condition of the battery?

Many thanks for your reply.

When I tested the output voltage, I did raise the engine speed to above 2000rpm, and it made no difference. The test procedure for the alternator says to raise the engine speed to 2000rpm, and measure the voltage across the battery terminals with the headlights on high beam. The voltage range given as good for this test is 13.9 - 15v. The test procedure then says to switch on the heater fan and the heated rear window and measure the voltage again; This time you're looking for at least 13.5v... I'm getting a full volt less than that with none of the above additional load. And it's this that leads to my original question:

In the 1996 charging circuit diagram (shown above), the 12v supply to activate the alternator comes directly from the ignition switch (via the BY wire), where in my car this wire is missing from the alternator completely; the voltage being supplied apparently from the engine ECU (via the WR wire): The question being, should I be getting a full 12v from the WR wire, and if I'm not, does it indicate a faulty ECU?
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