Re: Charging from tow vehicle

On Wed, 5 Mar 2025 20:03:57 -0000 (UTC),
  Ted Heise <theise@panix.com> wrote:

 On Wed, 5 Mar 2025 09:05:19 -0600,
   sticks <wolverine01@charter.net> wrote:

 The first place to start would be the 7 prong plug in, on the
 tow vehicle, and the vehicle being towed.  I am going to take
 it for granted most of us would be using a 7 prong plug. 
 Any differences are minimal and easily solved.

 So let's start on the tow vehicle.  It might surprise some of
 us that our plugs don't even have power in them as delivered
 from the factory. I have an F-150 and was quite surprised
 myself that I had to install an additional fuse to get my
 line hot.  It was wired, but not fused and inactive.  With
 today's CANBUS systems, it can be difficult testing this, and
 you really have to use a 12 volt test light and not a volt
 meter.

 
 My thinking was to take a reading from the LiIon battery app
 with the battery connected to the trailer and then with the
 fridge started (I think it may run off the batt for a minute or
 two). Then I would connect the 7-pin to the running TV and
 repeat these readings.  Does that seem like a reasonable
 approach?
 
 I need a block of time to get out to the storage unit for this,
 so in the meantime I figured I'd take some measurements at the
 7-pin. First I connected clips from my multimeter with the TV
 off.  Surprisingly, I got some sparking, may have been from
 touching across pins.  But once I had a good connection I got
 no voltage.
 
 Now this could be from the line not being hot (e.g., because of
 a fuse needed), or because a multimeter won't work.  But I
 vaguely recall having gotten a 12-13 V reading from the pins
 some time in the past.  So maybe the sparking blew the fuse. 
 I'm trying to run down where that would be and will let you
 know what I find.

Okay, I found the fuse (designated "trailer battery") and found it
was definitely blown.  Put in a replacement, and still get no sign
of 12 V at the proper pins (at about the 1:30 and 7:00 positions).

So I guess next is to ask the dealer to look at it.

Might look for a test light too, I guess.

--
Ted Heise      <theise@panix.com>       West Lafayette, IN, USA