Tranny does not shift past 2nd gear

Hi friends of mine asked me to look at there 98 Gmc Jimmy 4.3L engine 4X4, they told me when the Abs light would come on will driving the tranny would not shift past 2nd gear, so after a month of not driving it, I took it for a drive Abs light was out vehicle drove fine shifted good even took it on the highway still ran good, two weeks later problem is back Abs light comes on after driving for a few minutes and the tranny goes into limp mode can't shift past 2nd gear plus the speedometer was not working, could it be speed sensor on the tranny causing the Abs light and the tranny from working wright.
Thanks Paul

Yes, scan and look for codes and mph inputs.