I have a 92 ford f150 6 cyl. I put another altenator on it and now the battery lite stays on.. any ideas... Thanks for your time

 

Can we ask why you put another alternator on and where did you purchase it?

 

I changed it because the battery kept running down.. I took the altenator off another ford f150 that I know was good.. Thanks

 

You didn't test the voltage output with either one?

 

Did you do any checks to determine if the battery itself was good?

 

Take the battery and the ALt to your local Auto Zone or other auto parts store. Many, if not all, will test both for free.
This lets you start with a basis of knowledge.
Check the ground lead from the battery to the frame/body. Clean on both ends?
Regards,
Eric

 

yes the alternator checks good... 14 volts when running off the battery.. could it be a ground problem thanks for your time

 

What kind of test was run on the battery? If the alt is charging as it should there is the possibility the battery can't hold the charge. That is the first thing to check in a case like this.