I've asked this on a couple of other forums with no response:
I have a '96 K1500 with 350/4l60e/NP241C. Those parts are pretty much stock except I replaced the t-case with one out of a junkyard about 3 years ago. I don't think it matters for this problem, but it has been straight axled.
It won't upshift in low range at all. Shifts fine in high range. I did a little reading and found there is a sensor in the t-case that reads when you are in low range so the computer can adjust the shift points. There are only two electrical plugs on the t-case, one at the very back which I think is the VSS for the speedometer and one near the range selector which I think is the low range sensor. Both are plugged in. I don't really know how else to check/troubleshoot anything. Any ideas?
