Fan clutch not disengaging

I have a 99 9200 with a 12.7. The fan work as it should when I put air to it. So when I start the truck it’s engaged, I checked power to the new solenoid and I have power. However after I reach 125 psi it doesn’t disengage and I still have power. When I hit the manual fan switch, I have no power to the solenoid and it’s still engaged. So with these engines, do I need power for it to engage and no power to disengage or visa versa. Where might I check for an issue? Also the A/C isn’t turned on. Still maybe a bad high pressure switch?

 

Thanks boss. I’ll chase it this week.

 

Ok. So shorting the high pressure plug didn’t do anything. I also tested the wires and there wasn’t any power to the high pressure switch. Not sure if there should be or not. I didn’t have the AC on or defrost either. So my thought was to splice the ground wire to the fan solenoid and ground it to the engine. Bad idea??