90 Civic DX with stock DPFI motor...198,000 miles.

Brand new battery. Brand new alternator.

Voltage tester shows 12v on battery whether the engine is running or not.

The white output wire from the alternator also only shows 12v when the car is running.

I feel the problem must be in the four wires in the green plug that goes into the alternator. So we tested those.


What color/Volts/Volts with key to run/Volts when running
Black/Yellow 0/12/11.75
White/Yellow 0/.01/.01
Yellow 0/4.6/4.6
White/Blue 0/12/11.38

Voltage at the battery jumps to 14 right when the car starts and then goes back down to 12.

There is continuity between battery and the output post on the alternator.

Help!!

 

I've seen alot of these threads lately and it usualy turns out to be the alternator, even when they test good in the store.
See if you can exchange yours for another one where you bought it.

 

this is the third alternator that we have tried.