2013 Peterbilt 388

Um....@Rank or @wore out ??? Wish I knew. Those two are the PB specialists on here. I've only driven older 359's and 379's... Hoods.

 

The gauge should be multiplexed with no actual airline to it if it was a factory option. I suspecting this is an aftermarket gauge.
The gauge will be T eed into the air bag supply lines for reading the pressure.

 

My 2013 386 and 2018 388 have suspension gauges from the factory and they are mechanical. Lines go to the pass thru block in the firewall but not sure where they go from there but Im guessing it runs back to the suspension and T's in back there.

 

Factory load gauges just read the suspension's overall pressure. You load the trailer, CAT scale it, read the psi, then remember (writing it down is very important if you are forgetful) what that psi equals in terms of axle group weight.

 

Should be labeled on firewall manifold.