Why does my Caterpillar TH350B boom only work with the bypass switch?

[Nicholas Villa]

Our Caterpillar TH350B suddenly lost boom hydraulic function while working in the paddock. The boom will not operate normally, but it works fine when holding the bypass switch on the joystick. A mechanic checked the machine but could not find the fault. Has anyone experienced similar Caterpillar TH350B hydraulic problems or know what could cause this issue?

 

[Mr.PeterJ]

hey @Nicholas Villa If it only works with the bypass switch, I'd start looking at the safety interlock circuit or a faulty sensor. Since the hydraulics work in bypass, it sounds more like an electrical issue than a hydraulic one.