2010 Prostar stop engine warning buzzer

I bought a 2010 prostar back in Oct with 430,000 miles on it. We run out west, once it got extremely hot outside we have had problems, started with warn engine, went in shop they replaced turbo, and turbo actuator. Ran it 3 weeks stop engine and buzzer started going off none stop but truck seemed to run fine except derating on good pulls. Got back out of shop only got 1000 miles on it since last repair stop engine and buzzer starts again, back to shop same codes as last time was told DPF needed cleaning, cleaned DPF but was in too bad of shape so replaced DPF now here we are $20,000 later and less than 2000 miles back out of shop and stop engine and buzzer just a blarin' away.... Anybody experience the same problems?

 

ISX, codes are 2636 VGT actuator driver circuit which is red code. Amber code 1893 EGR valve control circuit abnormal update rate, and 2198 VGT actuator driver circuit. Inactive codes are 2288, 2387, 2346 and 1935

 

Our problem ended up being the wiring harness