With the key in the ignition and turned to acc, the truck turns off? You need the key in the ignition for the acc to stay on. I use a replacement key that was cut but not programmed. Turns the acc and ignition on, but won’t crank the truck over.
2017 silverado
i made an extension cable for this, works well. But if you have a WFCO converter in your camper be aware that after being connected to shore power for 40 hours the converter goes into float mode 13 volts, and this is not enough to charge your truck battery. If we go for a week I just flip the breaker off and then on in the camper converter and all is well in the world