robK

My daughter's '98 Civic HX is posessed. Thanksgiving night (of course) she called to say her car wouldn’t start. I drove over to her house and jumpstarted her car. The headlights were repeatedly flashing brighter dimmer brighter dimmer. I checked the battery voltage with my meter and it was jumping from below 12 to nearly 14 volts so fast the meter couldn’t keep up. My immediate thought is that the internal regulator was freaking out. I left the battery charger on so she could get to work in the morning. The next day I swapped cars with her and took the Civic home. I removed the alternator and took it to Advance auto parts. Since I didn’t want to waste my daughter’s limited funds, I asked them to check the alternator on their machine. The machine said it was working fine. I put it back on the car and checked the voltage at the battery – it was approximately 11.5 volts, i.e. not charging. I drove the car straight to Advance and asked them to check the charging system on the car. They brought out their machine and checked it and said everything was fine. I checked the battery voltage with my meter and sure enough I got about 14 volts. I swore to the guy that only ten minutes earlier the battery was not charging. He just kind of looked at me funny. I gave the car back to my daughter and told to wait and see what happens. It worked fine until the Friday before Christmas; same problem again. This time I just bought a new alternator and put it in. Seemed to work fine, 14 volts at the battery with the engine running. Problem solved, right? Wrong. This has been going on for months now. It works for a couple of weeks and then dies again. I installed a volt meter in the car to keep an eye on what was happening. Sometimes it stays at 14 volts, and sometimes it fluctuates wildly. Eventually the battery dies and needs a jump. It will act up for a day or two and then work fine for a couple of weeks. I understand there is a “load detector” somewhere in the system, and the computer actually controls the output of the alternator. My fear is that the computer is the problem. I'm desperate. Any ideas?

MJ0LNIR

With the fluctuations, I'd guess there's a loose/frayed wire somewhere. Have you looked them over well? Anything showing wear, checked all the grounds and connections, etc? Always check the cheap stuff first.

robK

Problem is, when it's acting up, the voltage cycles up and down rapidly; several times a second. If I start adding load, lights, blower, wipers, the cycle slows down. I would expect a bad connection to be more random, and not cycle like it does. I have checked the connections as best as I can, but all the wires are pretty secure. I'm hoping somebody on the forum has experienced (and solved) a similar problem.