I drive a 2000 vision, the Jake seems to only work when the truck is NOT up to operating temperature. When I first start the truck it seems to work fine, but as the temperature gets up to around 180 it doesn't work. I can hear a clicking noise when the Jake should be coming on. If I touch the clutch or shut the Jake switch off the clicking stops. Both wires going to the engine seem to have a good connection. One other thing that I knoticed is that when it is working, it works the same in both low stage and high stage. Does anybody know what the problem could be?