Alternator charge switch on 1991 Honda civic SI

[somedude88]

I think I'm using a bit over a 5 watt bulb now.. I'll try something bigger like maybe a full sized brakelight. Maybe tomorrow would bumm be out if I can't get this working since i have all this installed and wired up. Forgot to mention... The battery indicator on my cluster lights up when I try to disable the alternator with the light bulb trick

[lermo]

Has anyone figured out why this happens? I have the same problem as somedude88 with my alternator. Tried several different size incandescent light bulbs and no effect. I Cannot disable the alt field once it becomes energized.

[lermo]

one difference i have though is once the field is energized and then i disconnect the field wire to try and ground it with a light bulb the voltage raises to 15v+ while somedude88's remains the same after disconnection.

[serialk11r]

Originally Posted by some_other_dave

I don't know what wire is what, but Google should help you to find a PDF of the Helm manual for your car. (I know there's one out there for the CRX, which is just about identical mechanically to your car.)

Your car, BTW, already has an alternator disable built into it. The ECU reads a bunch of parameters like temperature and current electrical load, and turns off the field current to the alternator when it doesn't think the battery needs charging. It freaked me out when I saw that behavior the first time on the cheapie voltmeter that plugs into the cigarette lighter.

I used to drive my CRX with the fan on to force it to charge because I did a lot of engine-off coasting in it, including some with the lights on.

-soD

Wait, a 1991 Honda does this???
My 2000 MY Toyota doesn't The voltage reads a constant 14.6V when the engine is on and spinning over 900rpm.