Thor Forums

[Oneilkeys]

If the RV starts every time when the emergency start is engaged but does not start sometimes on just chassis battery power and the chassis battery checks out OK, then you almost certainly have a bad connection in your chassis starter system. The emergency start provides enough amperage along with the chassis battery to start the engine pushing thru your bad connection. The chassis battery alone does not. If you are knowledgeable about engines, you could get a starter system schematic (you have a Mercedes chassis?) and check all the wires. Probably will be easier to take it to any Mercedes or light truck mechanic and tell him you probably have a short somewhere in your starter system or a bad starter. It should be relatively easy for him to find and fix. This does not appear to be an RV problem.