Cummins N-14 Fuel Shut Off Solenoid

Truck was randomly shutting down. Customer brought in truck and I hooked up computer and had a SID 254 FMI 4 code for the fuel solenoid. My dad removed the wire to the solenoid and I removed and installed new solenoid and when I went to hook the wire up it was hot. I thought they had left the key on but it was off. I had 12.5 volts at the wire. When I hooked it up it went to zero. The battery light was on in the dash also. The truck fired right up and shut down like it was supposed to but still has voltage to the wire when wire was disconnected. It has since started reading 6 volts instead of 12.5. I was wondering if something might be going on in the ECM allowing voltage to go through there. (I would not imagine there should be voltage there with key off).