Honda-Tech - Honda Forum Discussion - Need help with electrical problem (very confused)

Hi all,

I have had my 2003 honda civic ex with manual transmission for 4 years now and this past week i've developed a strange problem that I can't figure out. I wanted to consult you guys before I take it into the shop in case I can fix it myself or just to understand the problem.

It started after filling up at a gas station. I started the engine and the airbag light came on, then went off after a few minutes. The next day, while driving, i noticed the abs, brake light and airbag light all came on, then a few minutes later the dashboard and the radio turned off. I pulled over and everything came back on instantly. I kept driving and things seemed fine for another 15 minutes, then it happened again. The radio and dashboard turned off but the power steering and the cruise control was still on, at this time i was checking the battery voltage with my phone/obd and it was reading 15 - 17 V. I pulled over and found out that everything works until i rev the engine, then the systems start to fail, abs light, brake light on dash, airbag light, gas light, then the dash turns off after stepping on the gas for 10 sec.

I started pulling fuses to try to fix the problem - one at a time, i pulled and replaced the radio fuse, the dashboard fuse, and plenty of other fuses but the problem remained until i pulled the fuse for the alternator. After this, there is not a single problem with any electrical system (except the cruise control will not turn on) and the battery voltage has been stable at 12.2 - 12.3 V for a few days now.

I know that without the alternator, I will slowly be discharging the battery every time I use the car so this solution is not sustainable, however it's confusing to me that the electrical systems fail while im monitoring the voltage to be 15 - 17 V at exactly the same time. My obd reader gets 5 - 10 readings per second so i really thought i should be able to notice an electrical problem here.

I have these questions:

Do I just need a new alternator? If so why does my obd reader record normal voltages for a working alternator?
Why would the electrical systems fail if the voltage at the alternator is OK?
If the electrical malfunction is downstream of the alternator, why did pulling the alternator fuse fix the problem?

I'm very confused and I don't want to confuse my mechanic by asking him to figure it out. I would be willing to run any test that i can to help if you have any questions for me.