Freightliner won't shut off

i have a 99 classic with a isx. This morning when I shut the truck off I turned the key and it did not shut off. It was like I did not do anything. So I opened the hood and pulled the wire off the fuel shut off between the metering valves. Truck shut right down I just replaced the shut off valve a mo ago. Put the wire back on. Instant power the primer pump started running accessories started going. Hit the start button nothing. I jumped the selinoid on the fire wall truck stated right up. Had to take the wires off to shut it down again. Truck is not shutting down on the timer either. Do I have a bad selinoid? Maybe the key switch? How can I test the switch or selinoid? I do have a multimeter in the truck.

 

It's a signature 600 so a early isx

 

I had that out and the stem the starter is connected to has juice. I'm thinking the key switch is bad

 

I don't know if the starter is getting juice from the key. But I can jump. It from the selinoid. I'll be home late tonight I have to dig in farther.

 

I have seen that box I just thought it was a inverter. It started to shut off and start with the key agin today. I'm going to look into it farther though it does have a problem that needs resolved.