DDDreamers said:
Unsure how we will temp install brake controller in rental.
Uhaul trucks used to have 12V constant power right @ the back of the unit.
While I would not suggest using those TERRIBLE, HARNESS DESTROYING "Scotch blocks" even on a Uhaul truck...with a test light, find the constant power and hook the controller up right on the tailgate...or the floor of the vehicle.
The cheaper "timer" style controllers are better for this, but we have used the super Tekonshas wired this way and duct taped to the floor of a cargo body.
(The truck used was a lot heavier duty that what you are likely to rent, but uhaul used to be same same/uniform in their (kind of strange) connection setups.)
If there is no constant power back there, just buy some #8 or #10 wire and a fuse holder. Connect an alligator clip to it and hook it right to the battery...then duct tape it to the fender and bring it in the door...then through the cargo body.
(Take the clip off when you shut the truck for more than 30 minutes, though.)
This stuff should work OK...
https://www.amazon.com/GS-Power-Pri...8&qid=1550679069&sr=8-4&keywords=#10+red+wire
and one of these...
https://www.amazon.com/VOODOO-Gauge...550679179&sr=8-10&keywords=fuse+holder+15+amp
DO NOT use "speaker wire" for this purpose.
There are (foolish) people who do this and will troll, but they are, quite simply, wrong.
You need power wire similar to the link. Make sure it has a bunch of hair-thin strands, NOT ten large strands.
DC current needs a sh!t ton of strands to carry the amperage effectively.
One other thing...if you do a temp setup of a brake controller, dont sit there with the brake lights on for 20 minutes straight in traffic. Put it in park and use the parking brake. Same with the 4 ways. If you have to use them for 20 minutes, disconnect the controller. (This is applicable to the less pricey "timer" controllers, not the ones with an inertia wheel design.)
....and to further elaborate on the different types, the timer cheapies that come on every time with a grab scenario you set with the adjuster wheel or slider...can actually be better for you. Slide your steer tires in the rain or ice/snow/train tracks...and the pricier types (at least my fancy Tekonsha) will send no power to the trailer brakes and you crash.
They use a kind of weight like a pendulum inside that requires the truck to start slowing in order to activate the trailer brakes.
I popped a rear caliper once and lost pedal.
It was instant "75% of my brakes vanished" feeling.
That fancy %&$^%ing Tekonsha just sat there and had I not been able to head for the grass, it would have made a mess.
With the cheap controller I installed that very day...form NAPA , in 1/3 of a second, it begins ramping the power to the brakes no matter what...and you adjust it to the proper setting for the weight/trailer.
I tow a 22 foot car trailer behind my 32' class A.
We weigh in @ close to 30,000 pounds GVW.
We have 14,000 pound axles on the trailer with the monster brakes.
Driving tractor trailers since childhood, I trust air brakes with huge reserve tanks giving you stop power, even with a blown line or a blown drum...not the hydraulic disc setup on our class A. That loss of caliper was certainly a "pucker" moment.
With that cheap controller and the station wagon loaded on the trailer, I can bring the whole shooting match to a HALT from highway speeds pretty safely and quickly.
The disadvantage is when you get into stop and go traffic.
You have to turn the power down on the controller, or the trailer brakes kind of...STOP YOU...a bit hard...every time you hit the brake pedal. For my needs, I would rather follow the KISS principle and adjusting the little slider bothers me not.
The car trailer is heavy, but I can back it up without leaving the drivers seat, it actually makes our rig MORE stable on the highway...and the toolbox on the nose of it carries welder/tools/spares/straps/satt dish/bodies of my victims...er, I mean "rolled up carpeting" yeah, thats it...
Hope the move goes well for you no matter how you end up doing it.
(Sorry to go a tad off-topic, but most folks miss this when setting up a controller...and people read these threads for years.)