OK to leave trailer brake applied without a trailer?

You can't always trust the trailer brakes to hold 80,000 pounds by themselves. It even says on the red button Not for Parking. I would still put some chocks and dolly down. Plus you can't trust that someone won't crawl under and back your trailer brakes off.

 

Good luck backing off the brakes if they're set.

 

All the electrical do-hickies in the world wont help when the entire system is pneumatic over mechanical...

 

Ok I see what you were getting at now... Trick the computer by bypassing the sensor... In theory that should work, but with as advanced as these systems are today its probably more complex than just bypassing the sensor.

But still a good idea.

 

When we ran idle shutdown timer on newer T800's, all the guys had to do to bypass it was unplug the park brake switch. The light blinked all the time, but shutdown never occurred.

 

Locking up the trailer brakes would work unless you happen to have a trailer not equipped with maxi brake Spring brakes and your trailer air leaks down during the night.
If you had this type trailer and the air leaks off your rolling away.
In my opinion the toggle switch method that @spsauerland gave you to fool the computer in to thinking “the brakes aren’t set when they actually are” is the cleanest, easiest and by far the safest way to achieve the result you want.

 

Fooling outside air temp works on some too. Need truck specifics.