Hi, I have an 03 manual. Truck will crank, but won't start. Has fuel. I am unable to check for codes via the key or a scanner. The lift pump will cycle when the relay is jumped, but still won't start. With the key on, the ac relay in the fuse box clicks rapidly on and off. The fuel gauge stays on E and the low fuel light stays on. Also the check engine light stays on. Grid heaters do not cycle as well. Hopefully someone can make some sense of this and help me diagnose.
Thanks.

 

i dont know, sounds like part of the truck is not being powered up. check all the battery cables, check and see if there good voltage going into the fuse box.

the left battery has 1 big red cable going to the starter and 2 smaller red cables going to the fuse box, there is a connecting plug on them half way.

that would be a good place to start looking.

 

So I went and checked the ECM plugs for power and ground. Test light showed power and ground through the plug. Went back the next day after a good rain and found there was no power in the plug, traced back the power wires to a connector, the wire just behind the connector was very badly corroded. Cut out the bad chunk and rejoined. Truck runs again.

 

Where is this connector located? I am having a similar issue

 

comes from a fusible link by the fusebox, under the intake horn, also has a ground wire that connects on the drivers side fender in the loom.