Q: Breaking system. on 2006 Jeep Commander

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While driving on vacation, my Traction Control light came on, along with the ABS light and the breaking system light. What type of problem could this be? Thanks for any information.
(2) Answers
(1) Comments
If all 3 lamps are on this usually means either a fuse to the ABS module is blown (there should be 2 dedicated), or the ABS module is disconnected - module is black plastic thing mounted to an aluminum block underhood that has 6 brake lines going to it check that the wiring harness looks connected. The ABS module itself may be damaged internally. Or 2 of the 4 wheel speed sensors may be damaged or incorrectly mounted and not picking up a signal.
Where are the wheel speed sensors located on the commander, and are they hard to replace? I can only find L/R rear sensors listed at parts stores and online, it makes me wonder if the fronts are difficult to replace. Any suggestions. Also can wheel speed sensors cause shifting problems? I have had all three lights on for a week or so, and I notice that in the evening my jeep doesnt want to shift well until i have drove it for a bit.