4r100 problems shifting into 4th
I have a 4r100 ats transmission, and in drive it wont shift into 4th just cruising at 50 mph. It will shift into 4th if i speed up to about 60 mph, then i press the overdrive button and use overdrive. I dont drive in overdrive because my overdrive will engage at 45 mph. I can get my transmission to shift into 4th at about 45 mph but i must have my ATS co pilot turned on an with two blue lights on the left lit up. Then my ATS co pilot wont work correctly in the rain or snow, which means i am without a 4th gear when its wet. I hate driving it in overdrive because overdrive will engage once i hit 45 mph and it just skips 4th and goes straight to OD. What would cause this?