Jake problem

Shop.

A can of worms as to the possibilities starting at your fuse box for a loose or rusting fuse feeding power to the Jacobs.

 

Turn off your cruise on the way to the shop,

 

Like the Jakes are turning on and off? Sounds like a connection type of problem to me, check the back of the switch.

 

Thats how those jake brakes work on that type of truck.

 

With the jakes "ON", the wire connectors on the jake solenoids are wiggling with bad connection from the vibration. Remove your valve covers. The solenoids with the wires going to them will be in plain view. Pull the conectors off each jake solenoid and use pliers to crimp the connections better so they are tight when you reconnect them.
I have lots of experience rebuilding jakes and jake diagnosis. On Cats though. IF its not a cat, check the soenoid wires anyhow.

 

Have had to do that several times, on Cats of course.

 

how different can the other motors jakes be? All this new junk out there, probably very different

 

Go to the dealer and have them check it.

 

Besides the switches on the dash, you have switches on the throttle and clutch pedal too, if you have a clutch.
Check those first to make sure they're adjusted properly.