Auto shift faults - please help

06 FL with Mercedes engine and auto shift started having intermittent issues shifting. Problem started 3 years ago and was corrected by having corroded cables cleaned. Twice more since then, same type of solution to fix it. Now on fourth time and have had all batteries cables cleaned, all transmission connections cleaned and ground connections checked. Still continues to fault as follows: While slowing down while coasting or using the brake, rather than down shifting it will display F alternating with the gear I am in i.e. F, 8, F, 8, F, 8 etc. I can sometimes correct this by either braking and downshifting manually at or below the shift point which occasionally will then upshift back to normal or by slowing down quickly below desired speed for that gear and accelerating which occasionally will force the downshift. Frequently, nothing will work or the gear indicator just flashes without the F and it will not shift up or down. When all else fails, I stop on the side of the road and shut down. After 2 or 3 minutes I'll be able to restart and continue. Sometimes it clears up, other times it will fault again even upshifting and I will have to shut down again. Note that the truck never fails to downshift up a hill. Only when on a flat surface or downgrade.

 

"This type of problem has nothing to do with the clutch. Without knowing what codes the transmission is throwing here are your basic problems that these transmissions have, bad xy shifter and harness, bad speed sensors."


Uh yeah Freightliner tells me I have a bad xy shifter and bad turbo speed sensor. But wouldn't it be cheaper to convert to manual than spending 2K+ to fix these items?