Helped a friend with his Jeep Grand Cherokee. It had a few parts replaced recently and started running real bad once warm. A few mechanics suggested that the ECU was bad and needed to be replaced. Decided to replace the crank sensor with a OEM part since the one installed was not. Just decided to take a chance since the truck was running real good when cold and got bad after it warmed up. So far so good. Whom ever changed the sensor a few days ago removed a metal wire guard that may have been insulating the wire at the top of the sensor. I put that back on with the new sensor.

P Codes P0351, P1391, P1494

Here is a video of the job that I put together. How to replace the crank sensor on a Jeep Grand Cherokee: