I need some serious help. On my way home my jeep decided to shut off while driving at about 25mph. I steered it to the side and tried to start it up again, cranked but no success. I popped the hood, everything looks good, all fluids are good. When I put the key in aux position the fan turns on, but the gas gauge, voltage, etc don't read as they normally do. This is where I get lost, normally in aux the gas gauge will read, but it stays flat and so do the rest. I just filled it up prior to this too... Battery is good, what could be the issue? Maybe a main fuse? Any ideas?

 

Do you have fuel? Do you get spark at the plugs?

It could be a bunch of things, so doing a little more diagnostics than just checking fluids is in order.

Check all fuses. Check all wire connections.

Does the CEL come and for a brief couple seconds when the key is in the "on" position? (Keep in mind, the ACC is turning the key the opposite way of starting the truck) If not, your ECU is probably toast.

 

I would check fuel at the rail. If that's good, check for spark at the plugs. Sounds like it could be the crankshaft position sensor, but I would test those 2 things first before just throwing parts at it.

There is a write-up in the Technical write up section about how to test the CKP as well, if you have a volt meter.