2001 Chevy Truck find a fuse for "Tow Mode"

Should have fuse block on the lower left side of instrument panel, a instrument panel wiring harness junction block at lower right side of the instrument panel and then an engine wiring harness junction block on driver's side of engine compartment next to the battery.

If your tow button is not working on the shifter, it is most likely because of a broken wire that runs to the end of the gear shifter. Very common issue on this model if silverado. I believe it's an orange wire, single wire than breaks at the base of the gear lever, underneath the plastic/rubbery protector.