[Deper10]

this is where the voltmeter is your friend.  and if you have someone that can be inside moving the merge switch it will save you some running back and forth though not necessary.  

first of all, with the merge switch in the middle position (off), measure the voltage on both battery cables on the merge switch.  meaning on each side.  they are big 4/0 red cables.  you should have 13v or close on each one.  so put one the red lead on one side of the solenoid and the black to ground.  and then switch to the other one.  

if you have 12-13v on each side, now to check the small wire terminal on the solenoid.  put the red lead on the small terminal and the other to ground.  you should have no voltage.   then have someone move the switch to the up position while you are back at the solenoid.  you should hear a loud click as it energizes.  and you should have 12v at the small terminal.  now move the switch back to the middle or off position.  you will likely hear the solenoid click again as it de-energizes.   now move the switch to the down position and you should hear the solenoid click as it energizes and you should have 12 volts at the small terminal again.  

so with this you are just verifying it is all working ok at the solenoid and it is the starting place to troubleshoot.

others may have a better way, so please pipe in

tom

Well I couldn't wait until tomorrow so I tried doing what you suggested and this is what I discovered. With the merge switch in the middle I only have 12.4v on the chassis cables and nothing on the house battery side our the small terminal. I also do not have any 12 volt working inside the coach. With the merge switch in the up position I have 12.4v at both the chassis and small terminal. Is there a fuse between the house batteries and the solenoid? I will try again tomorrow when I have some help. 
Thanks
Dario