columbia diff axle not workinh

Fuses?

 

This a diff lock for a tandem truck or one of those single screw/tag things?

 

Usually can hear it when it locks in. Maybe have a helper throw the switch, while you listen up by the front Axle. Maybe it’s just the light. If you don’t hear it lock in or out, you can take the line off at the power divider, see if it’s supplying air when switch is engaged. That’ll tell you if it’s working or not, or if it’s an air supply problem. You’ll see the air line going into the top of the axle.

 

Most of those switches are mechanical I believe (kinda like a reverse switch on a manual transmission). Definitely want to listen and try to hear if it is cycling. Not cycling then check the air like you said. If its getting air but can't hear it move, time to jack up the drive axles and try to spin tires by hand to see if it actually engages.