Electrical issue - haven't seen this discussed before

NHCraig

I've searched, but I haven't seen this come up before.  When I had my 7-pin connector wired, I asked them to wire the 12v power lead so that I could charge the T@B while driving (a 2018 320S Boondock, if that matters).  When I have the battery disconnect switch set to green so that I'm charging, my tow vehicle engine keeps running after I shut off the ignition switch!  Since it shuts off when I turn the battery disconnect switch to red, I assume they did something funky in the wiring and that the T@B battery is supplying power to my vehicle to keep the spark plugs firing.  Since I know nothing of 12v wiring, anybody have any ideas what they might have done?  I'll bring it back to the RV place that wired the 7-pin, but would like to have some info on what might be wrong.  Thanks!

MuttonChops

No expert here, that said . . .

Sounds like the Installer connected your trailer +12V to the wire (circuit) between vehicle Ignition On/Run position and engine control computer.

Installer should have connected the trailer +12V to the vehicle Main Battery Buss.

Attached PDF file has a couple of reference diagrams.

Would be helpful to know your Tow Vehicle:  Make-Model-Year.

Many newer vehicles now come with Main Battery Buss 'trailer' fuse locations factory defined for an Installer to use.

Also, always ask how your installer did the job . . . show me!

ColoradoJon

Yep - Check this out - different question but similar:

https://www.etrailer.com/question-60402.html

NHCraig

Thank you both for the info - gives me something specific to go back to the installer with.