[Carl n Susan]

Originally Posted by awheeler

<snip>
...Can I plug in the power connector to the truck while I'm on RV Park power? I want to check all the lights on the 5th Wheel.
</snip>

I am assuming by "all the lights" you are referring to the 12V lights associated with towing (Brake, turn signal, running and back up lights). If yes, then plug in to the truck, preferably while the truck is powered off, and do your testing. The 12V towing lights are completely separate from the Montana RV 12V circuits. There is no need to disconnect shore power or even the 12V battery power,

Truth be told, you don't have to plug into the truck to test the 12V running *LIGHTS*. This process will not check the receptacle on the truck (obviously because you are not connected to it), but it will test the lights , along with the wiring. Jumper from pin #4 of your male Bargman plug (the 12V charge line from the battery) to the various pins for the different circuits i.e. Pin #3 = Tail and running lights, Pin #5 = Left turn and Brake, Pin #6 = Right turn and Brake, and the center Pin is the Reverse lights.

Some folks plug a 12V automotive flasher into pins #4 and #3 to cause all the running lights to blink continuously. You will see this at RV shows and Quartzsite (where finding your rig can be difficult after a few hours at the campfire).