The diff lock light is always on, and it keeps beeping — even with the switch off.

Hi everyone, I need some advice.


I have a 2019 Freightliner Cascadia, and I’m having an issue with the inter-axle differential lock.


The diff lock light stays on all the time, and I hear a continuous beeping sound — even though the switch is turned off.


To stop the beeping and turn off the dashboard warning, I disconnected the electrical connector directly at the differential. That stopped the sound and removed the warning light from the dash.


However, I’m not sure if the differential is actually disengaged now, or if it’s still mechanically locked.


What could be causing this? A faulty solenoid? A stuck air actuator? A sensor issue?


Any suggestions or similar experiences would be greatly appreciated. Thank you!