? Voltage out of Rv Tow Plug

[retired on a mountain]

2014 E 450 With engine running lights on what should my volt meter read? Touching each pin and ground . And is the center pin a always hot 12 volt?

[Bama Rambler]

Here's a diagram of the Bargman plug.
As you can see;
Pin 1 is Ground
Pin 2 is Brakes (no power unless controller is active.)
Pin 3 is Tail lights (12 volts when lights are on)
Pin 4 is +12 Volts (12 volts from vehicle)
Pin 5 is Left Turn/Stop (+12 volts when brakes are on, intermittent when left turn signal is on)
Pin 6 is Right Turn Stop (+12 volts when brakes are on, intermittent when right turn signal is on)
Pin 7 is Backup Lights (12 volts when vehicle is in recverse) NOTE: (Also used for aux charging in some installations, and camera power in some installations.

[retired on a mountain]

Ok so plug 4 will be hot . And I could draw off that to my toad battery to keep in charged while towing ?

[Bama Rambler]

Yes, just keep in mind that it doesn't provide much amperage.

[PenJoe]

The center pin can be used for backup lights on a trailer. But on your E450, the center pin supplies 12 volt power only when the TV ignition is on. On our 2500TS, we had a toad and used that pin to supply power to a battery maintainer attached to the toad battery. When the TV ignition was off, the power was terminated to the toad and, thus, no battery drain.

[retired on a mountain]

Ok thanks

[seldent]

I am getting unexpected results testing the voltage at the TV plug. Brake output set to highest level. Testing the brake voltage I get only 6.5 volts when depressing the brake pedal. However, when using the manual controller I get a full 13+ volts. I’m not sure why I get only half the voltage with the brake pedal.

[myredracer]

If it's a proportional brake controller like a Prodigy P3, you won't get full voltage to the brakes unless you are moving and hit the brakes or pull the manual lever on the controller.

[seldent]

Thank you myredracer.