Since chasing down electrical gremlins and seeing a steady 14+ volts on the gauge my trans has been working great for about 3 weeks and a bunch of miles.
Today while backing out of dad's driveway after sitting a few hours, reverse goes away. 5 mile drive home and it stays in 2nd , 2500rpm @ about 40 or so. I get home, still no reverse, and I pull up code 87-High ratio fault. I have never seen this one before.
94 6.5 turbo GMC crew cab 4x4.
Any ideas about what's happening?