12 volt alternator issue

Wed Mar 30, 2011 10:17 pm

On the 340ih, I think the 7 year old 12 volt alternator went kapuutz :? worked flawless until now. I have double checked and cleaned all connections, checked battery 12.35v engine off, and 12.36 running. amp reads -draw

I have a idiot light wired in (diode) and it now stays bright red all The time with engine running at all rpm/s , usually when I rev engine to 800 rpm's the light will go out,,as alternator '' excites" and works as it should. Is there a way I can test the alternator,or should I bring it in for a bench test. any other things I can try,let me know. thanks guys,Jim

Re: 12 volt alternator issue

Thu Mar 31, 2011 6:41 am

Sounds like the alternator has failed. Remove it and have it bench tested if you want to confirm that. All the indications you have listed are of a non-functioning alternator. Probably the most common alternator failure is the internal diodes.

Re: 12 volt alternator issue

Thu Mar 31, 2011 8:46 am

Thanks BD. I will do just that.

Re: 12 volt alternator issue

Thu Mar 31, 2011 6:50 pm

Went to local napa dealer, checked my alternator,it ested good, putting out 15 + amps, he cleaned the external connections for me, and sent me home, to double check wiring, clean all connections...they all looked good, I checked alternator mounts, and cleaned the surface of the mounts, to make good ground, installed alternaor and everything was fine again. Must have been a combination of dirty connections and bad ground ...who knows, it works, and all is fine ! thanks,Jim

Re: 12 volt alternator issue

Thu Mar 31, 2011 6:53 pm

Sure beats buying a replacement!

Re: 12 volt alternator issue

Fri Apr 01, 2011 5:42 am

very true.