Hello everyone,

Backstory for the problem: while driving home in my Honda Civic 2004, the radio turned off in my car unexpectedly. After noticing this, I took out the radio, and plugged it back in. The AC also began to act up during this event, turning on and off again. My lights would also not turn on. I was lucky enough to make it back home, and deduced that my alternator was dead. Subsequently my battery also died due to this event.

I replaced the alternator, no problems. It was a bit difficult to get out. Now here goes my real mistake. I took off the negative battery terminal while the car was running. I found out after later research that this information was NOT RIGHT for checking if the alternator worked. The car ran fine, however, when I turned on the lights, the car died, and it made all sorts of odd jittery noises on the console. After a few tries, the car started again, and seemed to have no issue. The console read the correct mileage, the car revved with no problems, the AC worked, and the lights all turned on. The sun roof also worked, as did the radio.

Here is my question: Upon measuring the terminals for my battery (This is the proper way to check if your alternator works), it measured around 13.6-14V with no loads on. When I turn on all the lights, the radio, and the AC, the battery will drop to 12.5V. Did I damage something? I read a guide that it should always be at 13-14V, regardless of loading factors. Did the new alternator get fried? I saw some articles pointing towards the voltage regulator. I went to autozone to get it checked out, and they're widget was hooked to my positive and negative terminals. It said my starter was good when I started my car. Said my battery was charged at 100% (should be since I bought it today), and it also said that my alternator was charging, the voltage regulator was working fine, and that all the diodes were good. Am I going crazy? was the article I read wrong? Please help. Additionally, I'm getting confused reading about honda ELDs. Is this normal function?

Article that is making me hysterical: https://troubleshootmyvehicle.com/ho...e-alternator-1

 

How did the tester test the alternator if it was just hooked up to the positive and negative terminals? wut.. Also, are your grounds and battery connections clean and secure?

I had my alternator die on my 90 Civic in 2016, which caused the charge warning indicator to go on. Autozone tested it more than 4 times and it tested fine in their machine. Took it back home and had the same problem. Had Samsclub replace the battery for free at 2 years 10 months under warranty, since it tested bad. Bad alternator probably killed it. Same issue-- no charging voltage with a charge warning light. The dude eventually gave up and replaced it under "customer satisfaction" and I haven't had an issue since. That alternator also tested good at the store.

Those testers and machines aren't foolproof. I even showed the Autozone dude a picture of my charge warning light with it installed. The alternator does sound bad, and I'm pretty sure the 2004 Civic has the regulator integrated into the alternator.

My buddy's 2002 Civic EX had random SRS and ABS lights and would flicker them nonstop without a charge warning light always present. Turns out his alternator was charging upwards of 16-20 volts nonstop. I assume his regulator was bad, too, since it went away with a new alternator. New alt kept the voltage consistently at about 14v. It's been about a year but I honestly forget if it stayed above 13.5v with accessories turned on. Maybe somebody else can chime in on that one.

This year Civic, like most, grounds the alternator through the mounting points. Is the mounting surface clean, and are the mounting bolts snug? This may be another thing to check for your phantom issues. Loose alternator mounts cause huge issues on this generation.

 

Hello Mr. Sumdewd!

My battery terminals are clean. I JUST replaced the alternator and battery, so they should be good. I have not looked at my grounds. However, I did something stupid and took off the negative terminal of the battery with the car on to check the alternator just after I installed it. From what I understand, the battery acts as a large capacitor that is used to filter any spikes from the AC alternator. The car was idling fine, however, when I turned on the lights to my car, the car died. After putting the terminals back on the battery, the car started again, and it seemed to have no problems. The problem seems to arise from the voltage reading across the battery going down to 12.5V when the lights, ac, and radio are all turned on. However, there seems to be no dimming of the lights, and the voltage across the terminals jumps back up to 13-14 volts when the loads are turned off. I'm really freaking out that I messed up something in the car by taking off the negative terminal of the battery when it was running. If it did damage the voltage regulator that is in the alternator, then it wouldn't be a hard fix. The radio is playing loudly without interrupts. I suppose I can just wait it out, and if the battery charge light comes on, I can just go back to the car store and get replacements. Hopefully that would fix the problem.

I am also confused about how reading across the battery terminals would check if a diode was good. You need to measure the ohms across the diode to ensure that one way has much more resistance.

 

Are you still having issues? I mean, I'd just drive it and see if the issue returned. I've been driving my 90 Civic on less than ideal voltage basically the whole time I've owned it. Never had any real issues.

 

No, not as of yet. Just noticed the voltage dropping to 12.5 when I turned all the loads in the car on. This was after I attempted the idiotic, "remove the negative when the car is running" action. It is what caused me to test it as per the article I first attached, and what gave me such a fright when the diagnosis said the alternator was bad. This lead me to believe I had damaged something. Everything else works fine. No errors on the dashboard. There is a picture of a person on a seat with a circle above him that appears on the center of the dashboard, but it terms off after a few seconds. The check seatbelt light works still and beeps annoyingly still. I'm probably just being a worrywart. Worst case scenario I'll just replace the alternator again. My big fear is that taking off the negative terminal while the car was running would damage anything important.

 

Usually just the brushes need replacing.

 

I have the same issue in my 05 LX. It still drops to 12.6-14 under load, dropping when I'm idling and increasing as I drive. Hasn't given me any problems so far but I don't know if it is normal.