Hey guys a few weeks ago I put a new battery in my truck and yesterday I went to start my truck and all the lights on the dash were bright in the run position then when I'd turn the key to start everything would die and the starter would click or turn over real slow. So I check all my grounds, fuses, and relays in the fuse boxes and found nothing. This morning to truck cranked up just fine drove it to the parts store and had the battery tested and the battery was bad so put a new one in there drove it home went to crank it up the starter clicked then the truck cranked up and it's done that twice. What could be causing this? My starter or starter relay.

 

Or alternator. Got a multimeter? Do some isolation before you go throwing parts at it. The relay is on the passenger side firewall, next time the truck won't start leave the key On and put a screwdriver across the terminals. If that starts it, it's probably bad. If not, check voltage at the battery and go from there.

 

What I did was clean off my battery terminals with sand paper and the 3 connections on my starter. That fixed the problem. If you want to test your alternater just pull off your positive battery terminal with the truck running. If it drops engine speed it's bad.