Quote:
Originally Posted by Schiappiv
2016 Airstream classic
If trailer batteries are removed will the power jack run off of my tow vehicle battery when the trailer and tow vehicle are electrically connected?
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Possibly. It depends on a few things.
I'll explain and then provide my answer at the end of my post:
Look at the
12v wiring diagram in your owners manual on page 8-18. Find the following four
Bold Print items listed on that diagram and look at the wires that connect them:
Find
M1 (7 way plug) and follow the 10 ga charge wire that connects to
M4 (the 12volt + positive copper bus). This wire connects to circuit breaker CB3 then feeds current out through circuit breaker CB1 (when the tow vehicle is providing power). The positive battery cable is connected to CB1 and goes directly to the (+) positive terminal clamp at
M2 (the battery).
Now find
M10 (the hitch jack). Note that the (+) wire that feeds it is also connected to the exact same positive terminal on battery M2 where the positive battery cable comes from the (+) copper bus bar. How these two wires connect to the positive battery terminal clamp is key in how this works.
Now the answer:
If those two wires that connect at the positive terminal clamp at battery M2 are connected to each other, so that current can flow through, the jack will work with the trailer batteries removed while connected to a tow vehicle.
Even if those two wires are separated, if someone is knowledgeable enough to hold those wire in contact, the jack can be easily be made to work while connected to a tow vehicle, even with the trailer batteries removed.
If you are considering this for security, I suggest going one step further. Remove the 30 amp fuse that is in the wire between the jack and the battery. That fuse is a special slow blow fuse that most thieves will not have. Most people do not even know the location of that fuse holder. When/if you take it out, take that opportunity to purchase a spare. They can be really hard to find at the most inconvenient times.
PS
One other caution from my personal experience: If you remove the positive battery cable and leave it loose in the battery box and the trailer is connect the tow vehicle, that terminal will arc to the aluminum if it comes in contact. The spark created can instantly burn a hole in the aluminum skin before a fuse will blow or a breaker will trip.