I noticed this weekend. I parked the AS at the campsite on Friday about 6pm and left the tow vehicle (2010 Tundra 5.7L) connected including the electrical plug. the keys were out for the ignition switch. I didn't notice any interior lights left on in the truck. The AS was connected to shore power from Friday until Sunday morning. When I came to leave on Sunday when trying to start the Tundra the engine turned over slowly but fired up. I think the two days the Tundra was plugged into the trailer is the longest I've kept the trailer harness plugged in. My Tundra came with the factory tow package (receiver, 7 pin connector etc) so I'm assuming when the ignition is off the TV should be isolated from the trailer.
The only 12v
devices I used was the lights and the water pump.
How is the best way to determine if the trailer is drawing from the tow vehicle?
I have the trailer at home. I could measure the TV battery voltage and then plug the trailer in like I did at the campsite and measure the TV battery voltage after 24 hours.