'96 K1500 Won't upshift in low range

[maddog411]

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?

 

[Ron]

check the one near the shift linkage, make sure there are an equal number of pins on both ends.

Almost all tcases going back to the early 80 (late 70s) will have a 2 wire connector there to illuminate the 4wd indicator lightt inside the cab, later models will also have an additional sensor to tell you when it is 4Lo

What I suspect is you will find the tcase has 2 or 3 wire outputs in that pin (even if it is a 4,5 or 6 in connector) and the vehicle side has 4 or 5 wires...

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?