freigliner problem

ECM fault codes?

 

With key on eng. off. turn crz. switch on flip other one on till lights on dash flash an count yellow and red flash
es untill you have total list of codes

 

use dashboard to pull codes

seems to me u have MR(PLD) to FR (VCI-ADM) can wiring problem.

 

I had one, one time, that drove us nuts trying to find a dead pedal issue. Was loosing the 5 volt voltage signal. After 10 hours of tracing trying to find the problem, we found it by disconnecting each engine sensor one at a time. Turned out the driver liked washing his engine. Water had gotten into the delta-p sensor (inside the sensor, not the plug). The resulting corrosion was causing a direct ground fault (short) and pulling the 5 volt signal to less than 1 volt. Replaced the sensor and all was well.
May be something similar on yours, but the only way to trace is to disconnect each sensor one at a time and check the pedal response for each one.
Note also: the wiring pigtail from the main harness and TPS can go bad also due to its position behind the trim.
Good Luck!