How to know if PCM or wiring harness is bad? - Ford Truck Jul 06, 20161987 - 1996 F150 & Larger F-Series Trucks - How to know if PCM or wiring harness is bad? - It 95 F250 XL with 351W E40D. Here issues it run great next day when turn off then start it run ok but when hit pothole or stop. It will idle high plus transmission refused shift 3 Ford Expedition Wiring Harness | Auto Parts Warehouse That's not a problem. We've worked hard over 11 years designing a website experience that makes it easy for anyone to idenify whether parts fit their car. Just plur your Ford Expedition and Year into the Year Make Model selector above and when you search for a Wiring Harness Auto Parts Warehouse will only show you parts that fit your vehicle.