7 codes J1939 system down

[tree98]

ok, so after spending needless hours on this yesterday going down quickserve rabbit holes that went nowhere, I had a little clearer head this morning and followed your advice Rawze and Sig and here's what I found.

I looked at the wiring diagram on quickserve and sure enough all these components shared the same 5v supply. A test light confirmed no power to any of the components.I also see there's a 15 amp fuse for that circuit, so after tracing the wiring harness to see which fuse panel it went into I found the fuse and it was blown.

So now I know why there is no power to the circuit just not what blew the fuse, atleast im getting somewhere now !! I didn't have any 15 amp mini fuses so i went to napa and bought a couple packages. Come back and put a new fuse in, turn the key on ...snap... blew it immediately, well that tells me I must have a dead short that's actually good news because that means the problem didn't go away and maybe it's not intermittent and I have a good chance of finding it easier! Next I unplugged all components on that 5v circuit, put a new fuse in and started plugging them back in one at a time and checking the fuse after each one until I got to the outlet NOx sensor and...snap... Found it !!

I wanted to be sure it wasn't a wiring or plug problem before I replaced the sensor so I put a load on the plug with a headlight bulb and checked the voltage it was a little over 12 and the fuse didn't blow with the bulb on so now i'm positive it's the sensor itself. Went to the dealer bought a sensor put it on, hooked up insite all codes inactive, cleared the codes and everything's back to normal !!

So i guess the sensor must have been shorted to ground internally. Thanks for the help guys!!