yep LaGrange i came to the same conclusion after doing a bit of checking.
Now i did find something else i had that deals with an ET-B series and the code 45 reads the same saying the PC contactor is open when commanded closed.
Says the PC contactor or it's related wiring may not be functioning correctly.
Says to run Test O00 - toggle the PC Contactor. Then says the PC Sense circuit may be bad. Then to test the PC Sense Voltage using test A00.
So the PC Contactor test is a different number from the other info i was looking at. Also the Sense voltage test is different.
So this model is slightly different then the newer one i was looking at earlier.

When i was saying to test fuses Donald i mean those large fuses on the buss bars on the contactor panel. There will be some large fuses they will range from maybe 70A up to 500A, depends on how many motors the truck has, there may be as many as 4 of those buss fuses. They are fairly big and do not look like your normal fuse. They have a round body with tabs on each end used to bolt them to the buss bar assy. You have to remove them to test them.
Also check the plugs on the Vehicle Manager JP4 is the deadman switch connection (it should be marked on the vehicle manager). You can check continuity there at the plug coming from the switch to make sure it is working properly. It should be wired to wire 3 to common and wire 4 to the NO side of the switch.
The PC Contactor circuit also plugs into the Vehicle Manager at JP2 or JPC8, check the contactor coil through the wiring that way. I do not have the ohm rating but it should not be open or dead shorted.