I have an 85 f150 it was starting fine one day had a little trouble while idleing but nothing major. But then one day when I was taking out a trailer break box ( previous owner installed) I tried to start it up agian and it wouldn't start it made a very weak two second attempt then made a loud thud sound. I tried it a few more times and it did the same thing so I read up on it and replaced the starter and starter silinoid it helped a little but then did the same thing. So I continued and replaced the alternator and voltage regulator but when i tried to start it I didn't have any power like before my lights would turn on and then when I tried to start it died but this time I didn't have any power what so ever. It's giving me a serious head ache because I can't pinpoint the exact problem please if anyone can help I would deply appreciate it.

 

Your headlights do not work? If so, you have a problem over at the starter solenoid or a main ground problem on the ground cable from the battery to the engine block, or the ground strap from the engine to the firewall.

You main power is tapped into at the starter solenoid large terminal that goes to the battery +. It's a smaller wire that has some fusible links in it.

 

No my truck is the one that's not starting although my turn signal is messed up also I turn it one way and I get hazards also I don't have running lights