here is a problem that i need some help from my fellow H-T members

i bought a crx last week from craigslist, and as i drive back from the buyer's house. i notice the check engine light came on. however, i thought its probably some O2 sensor. so.. as i approach my exit on the freeway, i notice all my interior lights started to go dim, so i thought it was battery or the alternator. make the long story short, i got both the alternator and the battery replaced, but alternator still doesnt recharge the battery. when the car is off, the voltage is around 12v, and once i start the car it drops down to 9 or less. i cant figure out what exactly is wrong with the car. both the alternator and battery are good, what do i need to do to fix it. PLEASE HELP ME!!!!!

 

did you check the code for the CEL? - my guess would be that it was a code 20 for Electric Load Detector which usually means that the alternator is not working correctly - what kind of alternator did you get? - a lot of aftermarket rebuilt alternators from places like Autozone are just junk - the alternator should be putting out around 14v-15v - the car runs from the alternator, not the battery - the battery only starts the car - once it is started, it will run if even you remove the battery completely - sounds like the alternator isn't working and it is trying to run off the battery, which just drains the battery - the fully charged battery should be reading about 12.5v with nothing turned on

just to be safe, check to make sure that the alternator wire from the engine harness to the main fuse box, under the hood on the passenger side, is connected, clean and secure