Honda Alternator with ELD

[Gasoline Fumes]

The 1991 Honda Civic Wagon I'm currently driving has an Electric Load Detector in the charging system.
Description here:

I monitored the voltage while driving and it works exactly as described 19 years later.

But I don't understand why it goes to full voltage above 65 km/h (40 MPH). I'm usually cruising at 50-60 MPH. Should I be thinking about tricking the alternator? I'm not yet sure what kind of signal the ECU is sending. Or should I be thinking about cutting the VSS signal in half? Any reason for the ECU to know the actual speed? The VSS is in the speedometer, driven by a cable, so no issues with displayed speed on the gauge.

[Piwoslaw]

A few new cars (BMW, 'eco' versions of certain European cars) have something similar - the alterator is cut off when not needed. I had no idea this was in production cars two decades ago.

There was a thread on automatically turning the alt on/off (can't find it right now), and there was a discussion on the conditions for turning the alt on. This should go there, maybe a crosslink?

EDIT: Found it! Preparing to crosslink...
Automatic alternator cut out/regen braking

[bgd73]

interesting.

I got one of those cars that has ecu and carb versions, years overlapped.

I bet it is in alot of ecu'd cars and not described, else, like a home pc it would burn. in the old days cars just simply fried thier rear quarters off.

at idle I have an alternator that refuses to be full below 750 rpm.On the same model car with injection, it went to 500 rpm idle too, like I am now, but no difference in volts to notice, lights stayed bright...
it may explain steellasting aslong as it has (I started attacking old steel when my car turned 20)

hmm.
I humor it the natural way and continue with a few more led bulbs...seems to be working.
interesting post. Subaru in contrast had connections never documented..always genius, but a gripe not knowing. That too is over 2 decades..like alot of japanese with complexities way ahead..