Charging issues on D15B

[jemo]

Cross post/update from FB page. Ive got a Minitec kit and JDM D15B. The car starts instantly, runs good although the idle is a little high. I'm seeing problems in the charging system I can't pin down. I initially thought it was because the belt was slack but I don't think that's the case.

Battery is fully charged: 13.1V. I read the alternator grounds thru the transmission and valve cover ground. I measured resistance on those grounds, thermostat, harness ground, grounds from the subframe to body, and from the negative post to the body. All show same Ohm resistance (0.6). I measured resistance from each point with a jumper wire going direct to the negative post.

I also had the alternator tested at the parts store, they said it was fine.

I'm stumped. Grounds appear to be good, battery is charged, alternator tests fine, belt is not slipping or squealing, and car is running off the battery. Voltage gauge showing 11-12V. Any other ideas please?

Jeff

[Oz]

I still think your Alternator is faulty - you said on FB that the output with the engine running is (on a test meter) 12.1v and it doesn't change with revs. The Alternator should be putting out approx. 13.5-14.5v so if its putting out 12.1v then it is not putting out enough.

[jemo]

Thanks Oz. I don't know what else is wrong so I think you're right, I'll just replace it.