Out Of Time

But dont ask how/why. Question, I have parked on tbe side of the road with the 4 way flashers on. Will they drain my battery by morning?

Your batteries should be fine. Does your truck happen to have the ability to self start if your batteries start getting low, just in case?

Stay safe on the shoulder.. it's dangerous there as I'm sure you realize.

Hugs.

Likely to be alright as far as battery, however if have apu , it will charge battery while running or get up every few hrs and run truck for 10-15 min to be sure

APU:

Auxiliary Power Unit

On tractor trailers, and APU is a small diesel engine that powers a heat and air conditioning unit while charging the truck's main batteries at the same time. This allows the driver to remain comfortable in the cab and have access to electric power without running the main truck engine.

Having an APU helps save money in fuel costs and saves wear and tear on the main engine, though they tend to be expensive to install and maintain. Therefore only a very small percentage of the trucks on the road today come equipped with an APU.

Your batteries should be fine. Does your truck happen to have the ability to self start if your batteries start getting low, just in case?

Stay safe on the shoulder.. it's dangerous there as I'm sure you realize.

Hugs.

Thanks Susan. Its a pretty quiet road....just dark. Am parked almost 4 feet off the white line. Don't know much about this truck (2016 FL). The fact that it doesn't idle unless you accelerate once the engine light starts blinking leads me to believe that it doesn't do much on its own....

Try this if it's a manual tranny... Start your truck normally. Put tranny in neutral with splitter on high side. Turn cruise control "on". If your FL is equipped with "Opti Idle" doing that will cause your truck to start on its own if your batteries begin getting low. If you accidentally bump your shifter, it will cause the Opti Idle to shut off.

If you have an opti idle equipped FL, once the truck is running and you are out of gear, range selector in high, and cruise control turned on you should see a flashing yellow light on the dash. The light should read "IDLE MGMT". If you see that than just ignore the truck. It will turn off on its own in 5 mins. At that point the Yellow IDKE MGMT light will go solid. The truck will now start on its own if it needs to.

If you have an opti idle equipped FL, once the truck is running and you are out of gear, range selector in high, and cruise control turned on you should see a flashing yellow light on the dash. The light should read "IDLE MGMT". If you see that than just ignore the truck. It will turn off on its own in 5 mins. At that point the Yellow IDKE MGMT light will go solid. The truck will now start on its own if it needs to.

If you have the DD12 automatic like I do just turn on the cruise like Patrick said above bit then go to the sleeper and push the mode button once on the opti idle thermostat panel while the idle mgmt light is flashing. Once it tries to shut off it should go solid and then stay running.

FWIW, alot of times I leave my marker lights on for the whole ten hours I'm parked without turning on the tractor. It always starts right up after my break. I don't know how much extra power the flashers would use, but just marker lights shouldn't be an issue unless one or more of your batteries is weak.