Yeah, it suggests that, but I sure can't find it. Yet. It may take a gallon of kerosene and a match, but one way or the other this will be resolved!

It seems that just the right vibration renews the connection, wherever it is. I checked the ECM chassis ground, and it's OK, but I'll check again. I cleaned the rear mounting bracket with alcohol since a previous owner had spilled a lot of Coke or Dr. Pepper into the area.

I guess that's why Isuzu put a plastic tutu over the connectors.

Now I'm looking at a fault in the ignition circuit. I pulled the main relay again and checked the power to it and it's fine, so I'm now thinking it's the ignition switch circuit that energizes the coil in the main relay. The relay coil ground is OK, but I ran out of time to look at the ignition.

Oh, and the truck never quits once it starts. If it were a bad conection in the ignition circuit the coil would just quit giving spark and the truck would die. Kinda sounding like the ignition switch circuit that energizes the relay coil.