how do you test the currant sensor #3 ?

hello s/n is ETB5B51200
just to update, we had the local cat dealer come out as we could not find anything on this. they said it needs the logic board. they supplied one to us and geuss what. same thing. code 49 the instant the machine powers up. we do have poewrsteering but no lift or drive?

i would say both, make a visual check for any loose, disconnected, damaged wires or any other problems like worn out brushes or corrosion related issues, excess build up of carbon dust etc.
You can also use a vom to check the motor fields, and wiring through the harness etc.
Basic troubleshooting routine skills pretty much ;o)

how do we test for wire breakage in pump motor? is this a visaul test or a electrical test with meter?

having a truck serial number would help make this accessment more accurate but based on a general code chart for this model code 49=
wire breakage in pump motor, faulty CS3 current sensor, faulty logic card.

check all wiring to the pump motor circuits and check the current sensor first, faulty logic card is last resort if nothing else is found and is usually rare.