I have a 08 F650 with the Cummings engine. I have almost 13 volts but the engine will not crank. When I turn the key the starter don't even click. Please someone help.

 

But what about the amps?


Did you load test both batteries individually isolated from the truck?

 

Harbor Freight has a battery tester for $20. Load test the battery. Then you will see if your putting out enough current to turn over the engine.

 

Ok so I replaced the batteries and had the starter tested, still nothing so I ran a push button and the truck starts, but here comes another problem. Now the truck is in limp mode and the speedometer don't work and the transmission will not shift out of first gear. I changed the speed sensor and still have nothing. The truck is still derating. Without this truck I am in danger of losing my business so someone please help.