Rep Power: 396

Battery light stays on constantly. Replaced battery and alternator in a 2001 civic ex coupe. What could be the problem, we cant figure it out. Also we cleared all the codes with the OB2 Sensor.....
Thanks

 
Rep Power: 319

Sounds like you have a bad ground some where... Do you have any audio equipment? check the ground wire from the engine to the frame too.

 
Rep Power: 0

kinda strange, i just had the same problem today.

i took it to the dealership just to make sure it was either the battery or the alternator, turns out it was both. they were due anways, with a 2001 lx coupe, it was time.

so i change them out, new battery, a good used alternator from the junk yard, and wala......wtf? Battery light is still on. Dealership told me that I probably got another bad alternator from the scrap yard....whatever. I went to some good mechanics I know, and they ran a simple test on my voltage on idle, and at 3000 rpm, just fine. So now what am I going to do? I'm thinking when I get home tonight, I'm going to unplug my battery for a few hours, and pull the ECU fuse under the hood, hell, I'll wait until tomorrow morning.

It's just too bad that that thing can't be reset with an OBDII scanner

Any suggestions? Or am I up the same creek?

 
Rep Power: 0

Most of the time, the sensors doing the tricks. The reset of the ECU probably will help. Basicali is good to know what was the problem. I don't like going to a dealer and geting false informations. They using the honda service manual sor diagnosis, and in some cases they will not go throug the whole procedure. They will replace ofthen things that are good.
So if the alternator was bad, then:
a) supercharge the battery -> destroy the batery
b) not charge the battery -> the batery can be good
If the battery was bad (sort of internal short):
a) lose voltage and battery power -> batery need replacement
b) in extremly rare situation will damage the alternator

You can try to charge the old batery and go to Autozone for o free batery test. Even if the battery test indicate that is not holding the power, is not an explanation for the bad alternator.
I don't know if Autozone can check the alternator, and if is free or not but you need to know what was the proble. If not you can end up again with the same situation if was some electrical short.