AugustMoose87

So I'll try to keep the back story short....

For a while (3+ years) the charging light has been on in the dash of my civic. I got it checked out, and my mechanic buddy said he couldn't find anything out of order with it (though he does work a lot more domestic than foreign work). He suggested it was a problem with the light, not the system, and that as long as I got it checked out every once in a while to make sure there weren't any new problems I could just leave it be.

Not sure if its related, but a bit later, the ECU burned out and was replaced. It was replaced with a used ECU that was a few numbers off in the last few of the part number, local honda tech said it would be fine.

Fast forward to a week ago, I'm driving some errands, first my speedometer stops working, then the radio, the rest of the instruments, lights, etc. I shut everything off and managed to keep the car running (though I couldn't shut if off because it wouldn't restart). a few more miles over about 30 minutes and got home. Hooked up my charger/starter/alt checker and found I had a bad alt. I took it out, to AutoZone and had it bench tested, it was bad, so I got a re-manufacture and put it in.

Go to run errands, same thing, everything dies, but with it all turned off, I can at least keep the car running for about 1 hour this time.

I check the belt, mount, bolts, harnesses, wires, etc, everything looks good. Checking the voltage, my battery has 13.1 when the car is off, and 12.5 when its running. I start working out of my Haynes manual, and come up with 3 possible causes.

First - I have a short. When the ignition is off, I disconnect the NEG battery cable, and can measure a voltage between the cable and the battery. Manual says start pulling fuses to find the short, but I pulled every fuse and the voltage was still there.

Second - My ICU might be bad. since the short wouldn't account for the low alt voltage, I kept working through the Haynes manual, and got to where the ICU was the likely culprit. I pulled it out and gave it a once over, but couldn't find anything obvious (like when the capacitor blew on my ECU). But I couldn't find any way to test it, and I don't have any other symptoms I hear about (light, wiper, defroster, etc. problems - though it is July and I haven't had a need for my defroster for a while).

Third - I don't know if its related to the other problems, but I just realized that my charge light NEVER comes on since my reman alt was put in. The Haynes says it should come on when the ignition is on, and turn off once the engine starts. I can force it on (telling me the bulb isn't the problem) by grounding one of the wires in the alt harness per the manual.



And I don't think its related, but just in case... every so often my CEL come on, code 6, coolant sensor as the car is warming up. Once it reaches normal temp, I can shut the car off and restart with no CEL, so my theory is that it just heats up faster than its supposed to, due to either a minor problem with the sensor or poor cooling (my radiator is in pretty rough shape).

Former User

Find a new mechanic.

Did you ground the Wht/Blu wire to make the charge light come on?

Did you reconnect the large Wht wire to the alternator? Is this wire also connected to the hood fuse box?

If the answer is yes to all questions, then I think somebody sold you a bum alternator. Return it.

AugustMoose87

Yea, I' have since moved, and now have no mechanic... except my self. Can't afford to find one just yet.

Yes, I grounded the white/blue to turn the light on, and yes, I checked the large white wire's connection at the alternator and the fuse box.

Guess I'll go pull out the alt and take it back... Thanks, I'll post what I find.

AugustMoose87

Yea, the alt was no good. The thing that worries me is I had the guy test it before I took it home, and it showed it was good. So I'm worried that there is something else wrong with my car that caused the alt to die, especially since I have a short I can't isolate.

I pulled every fuse one at a time to see if the short went away, and it didn't, so then I thought maybe I have more than one, so I pulled every fuse it the car at the same time (except the main battery fuse) and still had a short. When I pull the main battery fuse, only then does the short go away.

Does anyone have a wiring diagram that I could take a look at??? (the Haynes manual I have is actually for an Accord, not a civic, so I imagine the wiring will be different)

Former User

Have you installed the new alternator?

Did you remove the 50A or 80A fuse to eliminate the drain?

AugustMoose87

Yes, the 80 amp battery fuse is the only way I can eliminate the short.

And yes, I put the new alt in, and its working for now... I'm just concerned that if I don't get this short straightened out, I might burn out a third alternator.

Former User

Disconnect the large white alternator wire attached to the hood fuse box. Does this eliminate the drain with the 80A fuse installed?

AugustMoose87

Sorry it took so long to get back, been a crazy week. No, disconnecting the alt wire does not eliminate the voltage with the fuse in place.

Former User

The hood fuse box may have a short. Get a replacement hood fuse box from the junkyard and install it to see if it solves the problem.