Traction Assist. ???

[v_cruz]

I have a 2000 Yukon XL, about a month ago I changed the ABS Electro-Hydraulic Control Unit(EHCU). Ever thing was good the ABS light went off and the system is working because I have used it, rains every day here But the Traction Assist. went off and will not let me turn it back on, I have a manuel(Haynes)for the Yukon but a does not have the Traction Assist. listed in it. If anyone has any info about this it would be nice or if there is another manuel that I can get. I like working on my own vehicles and motorcycles to learn and have an ideal of how they work. Any info would be nice.
Thanks
v_cruz