2007 mitshibishi Raider not moving in reverse gear
 

My 2007 Raider with 4 speed auto transmission suddenly will not engage into reverse gear when shifted. Acts like it's in neutral. Getting 0736 & 1790 codes but visual inspection of internal gears show no defects & metal in pan. I have been told it's "probably" the soleniod controller pack not functioning to open the reverse valve and let fluid pressure operate the reverse gear. Rather than spending 100's $ on trial/error can I test the controller for this function? If so, how? Thanks John Boy