In this video I show the symptoms of a bad battery in a 2016 ford f550 with a 6.7 powerstroke, and how to emergency start it. I started at the starter with a test light on the signal wire and was getting a flashing light that corresponded with the way it was trying to start so I ruled out the starter and ultimately found the batteries at fault. use your own judgement and don’t do anything your uncomfortable with because I assume no liability for your actions. I attribute my successes to god and give him the glory.