CM 870 Engine Brake

[Truckdriven]

(03-15-2022 )Nostalgic Wrote:  Could be a lot of things. Bad connection in jake harness, poor contacts or bad solenoid, lack of oil pressure due to worn shafts or jake rocker bushing, bad o-ring in solenoid, etc.

You can check with the cover off at idle, look for oil gushing (or lack of oil) and test the solenoid by pushing the button down and see if you have an oil issue at the solenoid itself.

But would those prevent the ecm from commanding it on? When I watch it with insite it goes precisely with the ecm command on or off, I'm trying to figure out why the ecm doesn't command it on.