hey guys have a c2 cummins 6.7 hydro brakes . i am having problems with a very intermittent no school lights problem it happened once to me and every other day to driver but when it gets here itsfine but when it happened to me the master switch on the light on switch did not come on and lights didnt work so i went to get some tools and came back and the light on master was on and school lights worked fine and couldnt get them not to work very frustrating but i did notice that t\with master switch on if u turn key off the light on that switch stays on and the scool light work with key off but in a minute it goes out anyone run into this issue
I would try another master switch for the dash, could be a bad smart switch after the key is off , I believe some modules stay powered up for 30 seconds, those lights would be operated by the second CHM under the left panel, also there is a PDM there too
OEM trained in wiring and all engine platforms for over 20 years
i did check another bus and it is powered up for a bit after key off just strange how its so intermitten but i put a new switch in just to see but again it only did it to me once so unfortunitly i gotta let the driver use it an see what happens