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Let me know if any tires were replaced recently. I would start with a visual inspection of the rear tone rings. These are mounted on the outside CV joint on the rear half shafts or axles. They crack and spin, this will set the abs and cause issues like this. Next if nothing found we need to check the system for trouble codes. Not all shops have an advanced scanner to do this.
let me know what you find
what did you find on the abs(tone ring)?
did you check for trouble codes?
tire size if more then 1/4 inch circumference difference can cause this.
you need to tell me if you looked at the tone rings on the rear axles and if they have a crack. Tire size can also cause an issue with advance trac.
checking for codes is really important if nothing is found on the visual inspection
we can follow pin point tests when we get direction
ok, if the abs system has a fault like a wheel speed sensor the advance trac kick in. When a sensor stops working the abs/trac system thinks a wheel is not turning, for traction it will go into 4x4.
The tone rings can have a very small crack, axle really needs to be turned for good visual inspection. The abs system uses active speed sensors, cannot be ohmed out.
we need to use a scanner that can access codes and even show live data, all the wheel speed sensors.
while we are at it check the brake fluid and let me know if this vehicle has had the speed control recall. There is a switch on the master that can leak, jumper harness installed too.