Fuse inj1 was blown. Replacing the fuse got all cylinders firing again. The tech went over the harness and didn't find a short. Drove several trips on a rough road, pulled on the harness. Finally let the truck go with the warning that we did not find the cause of the fuse problem.
Three months later, the truck returns with the same problem. Replacing the blown inj1 fuse got it running again. This time I looked over the harness. The wiring goes from the underhood fuse box to the bank 1 coils and injectors. I didn't notice a problem. Pulling on the harness didn't cause a short and a scope display of injector and coil current ramps looked normal. I decided to look online for any similar problems found by others. Alldata, iATN and identifix had no silver bullet. D-tips had mention of a short found in the harness near the upper control arm. Now that tip didn't really help because when I looked everything over this particular truck had no harness in the area mentioned that could blow an inj1 fuse. BUT it did lead to me finding the short. It was like this.... after looking under, over and around the control arm area and coming up empty I was standing in front of the truck and leaning over the front grill. I thought well I'll try the harness flexing again. When I grabbed the main harness from that angle and pulled toward the front of the truck, the fuse popped and the misfires started. Looking very closely at the harness there was a small hole rubbed into the casing of the harness. Opening that harness I found that the hole was also rubbed into the pink wire from the inj1 fuse. Right in front of my face all along.
Kenneth Hayes
aka Deranger
