Truck will only click and not turn on
My truck has been running very weird
lately it sounds like there's a knock on the
motor but it's not it comes and goes but
today my truck made the knocking and
there was squeaking too. I parked the
truck to check and it died off. So I thought
it over heated. I let it cool off and came
back and all it does is click the battery is
good. I turned on the headlights and tried
turning it on and the lights dimmed and I
need help I don't know if the problem is
bad or I should buy a new motor? What
should I do?