battery light coming on - how to trouble shoot?

[GREASE FIRE]

a couple weeks ago i was having problems with the starter and the batteries so i returned them both and put interstates in. Then it cranked faster than ever but now after only a week the batteries seem like they are dead. The battery light on the dash is on (it was coming on when i had the old batteries and stays on all the time with the new ones). The alternator says "remanufactured" on it, i don't know exactly when but it looks fairly new. I tried to have them test it at autozone but they could not get a reading, and the guy thought his machine was not working.

Any suggestions on how to figure this one out? For now i guess i will have to keep the batteries on a charger overnight but i would really like to solve this problem. Any help appreciated!

thanks,
Paul

 

[BoostFiend]

Alternator or regulator is my guess

 

[MIDNIGHT RIDER]

Simple test = put a digital voltage tester on the battery terminals with engine OFF and read volts; then, do same test with engine RUNNING.

Engine OFF should read at least 12-Volts, more is better.

Engine RUNNING should read at least 13.5-Volts, 14.5 is better, more than that is too high.

This will give you some idea as to whether the alternator is charging or not.

 

[typ4]

greasefire. put your basic location in your sig so we know where you are please. Makes it easier to get help on the cheap for you. And what your truck is
Sounds like bad alt or reg if pre 92, check grounding of the plate the reg mounts to.

 

[onetonride]

i had the same problem...start you truck.. pop the hood, and push down on the wiring harness or move the wires around on top of the alternator... then check and see if ur light is still on.... i ended up replacing the harness and it fixed the problem....good luck

 

[Greenie]

I've had the same problem with my '93 IDI - cleaning the connections on the alternator fixed it every time.

 

[mojoman]

just a quick get-by....if your alternator gives you grief while on the road...I simply give it a good rap with a screwdriver handle, piece of pipe, whatever is hard and handy...will get you home at the very least...I've gotten 3 months before replacement doing this...when it finally poops...buy a rebuild kit and have at 'er...way cheaper than buyin' new or reman....and ya learn as well...



mojo

 

[Papabear]

just a quick get-by....if your alternator gives you grief while on the road...I simply give it a good rap with a screwdriver handle, piece of pipe, whatever is hard and handy...will get you home at the very least...I've gotten 3 months before replacement doing this...when it finally poops...buy a rebuild kit and have at 'er...way cheaper than buyin' new or reman....and ya learn as well...



mojo

i agree 100% but nowadays when you ask for a rebuild kit for a starter or alternator the parts guy usually looks at you like a confused dog I generally get a really cold reception when i ask for the parts to do anything myself, versus the expensive plug and play option. if i can reman/rebuild or fab my own i do, the parts guys in this town don't make any money off me i even build my own wiring harnesses if need be re-using the original plugs + pins. i mainly do it myself because than i get it done how i want versus a reman shop who will use the cheapest crap going ie. assembly greases, wiring, terminals.

 

[GREASE FIRE]

Simple test = put a digital voltage tester on the battery terminals with engine OFF and read volts; then, do same test with engine RUNNING.

Engine OFF should read at least 12-Volts, more is better.

Engine RUNNING should read at least 13.5-Volts, 14.5 is better, more than that is too high.

This will give you some idea as to whether the alternator is charging or not.

while running i am only getting 11 volts! and the batteries are brand new.
Is there any way to test to figure out whether the alternator is bad or just the connection is bad?
thanks,
Paul

 

[MIDNIGHT RIDER]

while running i am only getting 11 volts! and the batteries are brand new.
Is there any way to test to figure out whether the alternator is bad or just the connection is bad?
thanks,
Paul

You can test at the big bolt on the alternator itself; it should read over 14-Volts, but less than 15.

Testing at that point eliminates any wiring issues.


The regulator can be bad, but it will either not charge at all, or go wild with the voltage = way too high.