Truck Repair: 2000 f-350, ford f 350, battery cables

Question
I have a Ford f-350 that is have some kind of starting problem.  When I turn the key to warm the glow plugs its fine, but when i try to turn it over it starts to flicker and wont even try to start and the interior light goes on and off. i tighted the battery cables and it still does it. do you have any advice?

Answer
Hi Josh,
Remove the battery cables, check the batteries for state of charge, clean the battery cables where they actually make contact, and reconnect them.
If the batteries test ok, and are fully charged, look for loose or missing ground wires from the engine to the frame or firewall.

Van