Re: truck not firing or running
1663 indicates to the pcm
that there is a failure in the fdcs chain
open short in fdcs circuit
non powered idm
1668 is basically a communication error between the IDM
If i had to wager a guess your IDM
is no longer getting any power that would explain why its not running and the communication error
The other code is a exhaust backpressure malfunction detected not any relevance to your problem i dont think...
See if that could be the problem....
2000 f-350 SRW CC, 6" lift 22" KMC wrapped in 37" Toyo's, S465, Swamps 275/226, Studs, Springs, Pushrods, Gen3, TS 6 pos chip with Swamps Tunes...