Rep Power: 0

Hello everyone! I’ve been having problems for a while with my 2005 Honda Civic EX. The battery dies overnight from intermittent parasitic draw, and the alternator belt slips/squeals when starting up. It hovers around 12V after starting up, and squeals until it makes it to ~14V-14.5V. It does the same when idling about 50% of the time, or when turning on a heavy electrical load. Also, about 50% of the time the battery light does *not* turn on when the ignition is turned on. It does other weird things that seem to change day to day, e.g., the other day it drove a around ~12.3V consistently, but jumped to 13.8V whenever I turned. hit a bump, turned on the headlights, or put it in park (not just stopped, specifically when i shifted to park). The symptoms (especially the squealing) seem to change with temperature.

Diagnostic details:

1. No battery light or codes, even when battery light is working properly (on when ignition is on)
2. Engine block, alternator casing, and frame are properly grounded
3. Parasitic draw test: draw still exists after unplugging all fuses
4. The main alternator wire is at battery voltage
5. Car runs at either 13.8V or 14.4V, drops to 12V and starts squealing when fan and defrost are turned on
6. Car usually drops to 12V when idling, then squeals when accelerating until it shifts gears and jumps back up to 13.8V or 14.4V
7. 4-pin pigtail plug on alternator voltage test (against ground with ignition on): Battery voltage at IG, ~5V at both L and FR, and 0V from S (I could have these pins mixed up, but I think this is correct)

Repairs/replacements:

1. New battery (though it could be shot already given how many times it’s been drained)
2. New alternator
3. New negative battery lead
4. New engine ground strap
5. Thoroughly cleaned corrosion off positive battery lead and post
6. Unplugged and plugged back in the alternator

Of these, unplugging and plugging back in the alternator makes the biggest difference. That’s when I first got the battery light working again, so I think there's a short there or the plug is bad. There is a crack in the plug housing, but it still clicks into place securely, though I plan to replace it.

Are these the correct voltage readings from the alternator plug? If these voltages are wrong, could it be because of the plug or because of the wires themselves are bad? Could the damaged/loose plug really be causing all of these issues?

Thanks for any help!

~ Sol

 
Rep Power: 126

Squealing alternator belt means it's loose. I'd look into that.
What brand alternator did you buy? These are finicky cars if you don't use OEM parts. That could also explain why it's intermittent.
Have you tightened the alternator bolts fully? You might be having electrical glitches which tells me the ground wire isn't tightened. Do that before anything else.