Brake and ABS lights on and P8037 code

[CBari]

I am having a little trouble searching since the upgrade, I am sure this has been discussed before but my 03 has both the brake and ABS lights on and when I do a key cycle for codes P8037 shows up. I suspect with 267k on the clock it is probably related to an ABS sensor. I have noticed when driving at hwy speeds over the last week I had noticed a slight feel like a rear brake was engaging and the disengaging but only at hwy speeds. After lights came I haven't noticed this. Anyone have any good ideas whats going on or where to start looking.