if this truck has scr controlled hydraulics there is no contactor that controls the pump, it all goes through the scr panel. This is most likely an ev100 system and has 2 scr panels side by side. Now if this is the case there is a high possibility it also has a premium display panel, and even if it doesn't it still should be showing error codes in the display when any of the hydraulic functions are activated.

If there are no codes being displayed then first thing i would check are the main control (power) fuses on the power circuits. (the big block looking fuses connecting to the buss bars on the panel) There should be 2 of these fuses, one being a 325A and the other being a 500A, check those real close and make sure they are not blown out.
Next i would check the control fuses in the fuse block on the RH side of the panel, it should have several smaller fuses in it, they should be AGC type but sometimes they use ceramic ones, check those with a meter and also physically check the ones if they are glass and see if they are melted inside. Sometimes you can still get continuity across them and using a meter can fool you into thinking they are good when they still cannot carry the load and they open up during operation.

I would also check all the buss bar connections and make sure there are none burned, these would be obviously burned if they were loose and should be cleaned up and/or repaired.

you can also do what mike suggested too and check the signal on the pump control card at those locations on the terminals. Generally if there is a problem in this circuit it will display a code on the dash though.

just a few things to check for at first glance.