Engine and transmission computer troubles. HELP!

[fmc360]

This is my first attempt to communicate my problems with my
1989 PT40, 8v92 with DDEC1 and Allison 748 transmission. After
many hours with the professionals in diagnosis, it appears to
be a sensor somewhere....my symptoms are (1) between 35 mph and
50 mph with mid-ranch rpm of 1500 to 1600 the transmission
shifts between 3rd and 4th gear, (2) the retarder tries to
operate with acceleration, (3) all of the buttons on the shift
panel are illuminated at once with the selected gear the brightest
on the panel. I am thinking that all of these problems are
connected in some way.....? Has anyone experienced any of these
problems?

P. S. The coach is now with Stewart & Stevenson....and has been
for two weeks....I guess if they can't fix it you don't need it!

88101 PT40
Carroll & Sandra Wooten
Madisonville, Texas