My friend has the same truck as me and when you start the truck it surges and the coolant temp will go up and down on the gauge and on my scan tool. So I unplugged the sensor and it did the same thing. Any of you guys had ecm issues or wiring harness issues that involve the coolant temp sensor? Thanks Paul

 

are you talking power draw surge at idle?
if its at idle and its really cold out you will have a power draw surge I have never seen a surge happen at warm engine temp with the gauge bouncing. have you guys pulled the sensor for coolant possible swap yours with his and see if there is a diff,

 

Na its an engine surge. Just the coolant temp goes up and down and the idle will change as the temp does., I unplugged the sensor and it still does it.

 

Is it a cold start issue or does it hapen any time?