T-770 error code L7404 - (Controller not communicating) ... Help!!

[p4smitty]

I've swapped the upper left wiring harness with no luck - I've removed and checked the DEF pump - The machine will stop after 30 seconds with the lights coming on - not able to ramp up the throttle - just idles and then stops...

 

[Mason international]

I've swapped the upper left wiring harness with no luck - I've removed and checked the DEF pump - The machine will stop after 30 seconds with the lights coming on - not able to ramp up the throttle - just idles and then stops...

Good afternoon p4smitty, I have the exact same issue on my t740, what did you do to fix it?