My brother has an 89 F150 loaded with all the electrical goodies. Currently the battery loses its charge in about a day or so. He first had the problem diagnosed by a mechanic as a faulty alternator, well after two years it is doing it again. I took off the alternator and had it checked, it was shot, so we put on a new one. Guess what, the battery is still losing its charge. Any suggestions?

Thanks

 

Get a test light and hook it between the battery positive post, and the battery cable(take the positive cable off). If you have a significant drain, the test light will be bright. I would start at the starter relay/battery connection. Your alternator output should be connected there, along with everything else that runs the truck and requires voltage. You can see which one makes the light go dim, or completely out, which means no drain on the battery. You can also pull fuses in the fuse box to see if one of those makes the light go out.

 

From My gallery Page.

How to Find an Electrical Short?

 

Thanks guys, I will give these suggestions a try.