Replace the ignition switch.

 

It is a 2000 chevy express 3500 with 5.7 engine

 

Also,that is fuel pump relay power, disconnect?

 

It's the fuel pump relay under the hood and it is disconnected.

 

When the key is on it says check gages and the battery light is on.

 

Last post,key on,normal,looking further,that fuse powers relay center,so back to pulling relays,or inspecting wires leaving relay center,and the sensors you mentioned above,power comes from pcm,so the problem is before that, except o2 heater circuit

 

It sounds possible. When I hit the pothole the van cut off and I had a hard time controlling the vehicle.

 

Can't find in book,does that 5.7 have a oil pressure sending unit on side of block,3 wire connector, disconnect that for a test,on older models it's tied into fuel pump,12v is there,and if it internally grounds, problem

 

The one I found is on the back of engine block and has one wire. I unplugged it and still the same thing.

 

Alright, today my van is cranking up no problem. I think some wiring got wet some how. I put a new hose clamp on radiator in case it is leaking under pressure. I did notice a wiring harness going into the transmission (which is a 4l80e) that is leaking fluid into the electrical connector. It's possible that the plug dried out when it was disconnected.