91 Accord Alternator on and off

[splacker]

The alternator on my 91 Accord (both the previous alternator and the replacement) sometimes charges. and somtimes does not.

This morning the voltage at the battery (engine idling) read 14.5 volts.

Then this afternoon it was 11.9 volts.

I am also fairly certain that there is a short somewhere in the electrical system (test light on between disconnected negative cable and negative battery post), but I am not able to find the fuse to pull that will stop the draw.

Any help would be appreciated.

 

[Dual-500]

Download the wiring schematics. There is at least one (1) fuse in the charging circuit.

Oh, and it's not going to be a "Short", that's a slang word used for any wiring problem. A short is just what it implies, a physically shorter path. For instance, the large output wire from the alternator, the one on the lug by itself, that's probably red in color. It a "Short" developed in that wire between the alternator and the underhood fuse box on the passenger side wheel well, it would cause fireworks and fry the alternator.

Just for your info, not a lecture my friend. What you have is probably a bad connection or bad fuse. Corrosion, loose connection, etc.

BEFORE TROUBLESHOOTING WIRING, DISCONNECT NEGATIVE TERMINAL AT THE BATTERY AND LEAVE IT DISCONNECTED WHILE YOU ARE WORKING.

I would locate the "Battery" or "Charging" or whatever it's called fuse and replace it. Also, look at the fuse box under the hood for corrosion. Check battery terminals and if they are less than new looking, I'd replace them as it doesn't cost much. Buy aftermarket from a Car Stereo shop or online and get some decent ones.

Check connections at alternator. Pull the plug off and inspect for corrosion. When you reassamble it, swamp it good with white grease - the kind in the tube. That will keep water out.

If you find any corrosion or rust anywhere post it and pictures if you can.

Good luck with it.

 

[splacker]

Thanks. I have found no rust or other visual problems in any of the areas you have mentioned, including the connections at the alternator. I have wiring schematics in the Haynes book I have, but they are "typical" of the 90-93 Accord.

I have looked for, but have not found, the "battery" fuse. Do you think it might be the one labeled "Power Distribution" in the fuse box under the hood, or is it somewhere else?

Thanks for your suggestions.

 

[Dual-500]

It'll be in the box under the hood. It's the fuse that's between the alternator output and the battery. Just replace it. When troubleshooting this kind of stuff, the nickle and dime parts are just best replaced.

I was thinking a while ago, this could be the battery is wasted. On the 11.9v test, was the engine running? The 14.5v is a little high for idle, if the battery is hammered it may not be presenting a charging load to the alternator hence the high idle voltage.

I suggest you take the battery to a store and have it load tested. If you have a charger, put a full charge on it first. If the battery checks out good, then tear into the SOB or maybe have the alternator also load checked.

Lots of electrical problems lately on the forums.