I have a VT 365 and either the IDM is bad or the relay . If it turns out the IDM is bad do I need to take the bus to a IC dealership for reprogaming If so would it need to be towed . I have never replaced a IDM
Check the entire electrical path from the batteries to the IDM relay closely. The smart thing to do is feel them all when the bus has been running a while to check for heat at the connections.