I had a similar experience with a 2002 Denali around 130K. Upon pulling into parking spot, front brakes (possibly rh only) would grind and thump in the pedal. Sometime the ABS light would come on, sometimes not, but it never stayed on. Eventually for fear of damaging the rotor, I took it to GM dealership. Diagnosis: front wheel sensor corrosion. Result replaced both as lh side was in similar state. No problems afterwards, and not unreasonable expense considering the miles and salty winters.
NOTE: Service people can mean one to two things when they say speed sensor. The sensor is exactly than, it reads the rpm of the individual wheel providing data for both ABS and TC.
The second item they may be referring to is the ring in the back of the hub that the sensor actually reads rotational data from. These over time often get covered in salt, grease, and other
road debris preventing the sensor from getting a proper reading. Ask your technician which it is. One is a simple (not cheap) wire harness change. The other generally involves purchasing new
hubs which is considerably more costly.
The good news is on most vehicles, a small portion on the ring on the back side of the rotor is slightly accessible and debris and salt can be cleaned off. You can remove the hub assembly to access it all or you can raise the wheel of the ground, scrub what is accessible with a toothbrush or brass brush, rotate the wheel to do another section and so forth until you have completed 360 degrees. Bear in mind the other 3 wheels will likely be in the same condition. Do NOT use a steel brush as the magnetism of the assembly will retain wire pieces will be difficult to remove while the hub is on the vehicle and will interfere with the sensor readings.
Once you have them cleaned, and if indeed solved the issue, some have had success with blasting the exposed portion of the rings each time they handle a car wash spray wand, hopefully maintaining all 360 degrees over time.
With all that being said, if you go to a service shop, especially with a 2010 through 2012 Equinox take this document with you to prevent paying for a bunch of parts and labor that weren't the actual problem:
Vehicle: 2011 Chevrolet Equinox
Nature of Defect:
SERVICE BRAKES, HYDRAULIC:ANTILOCK:WHEEL SPEED SENSOR
Bulletin Number:
PIT-5171
Bulletin Date:
Aug 2012
Summary:
GMC/CHEVROLET: A COMMUNICATION FAULT, REGARDING SERVICE STABILITY TRACTION AND ABS REAR WHEEL SPEED DTC OR CHASSIS EXPANSION BUS, WHICH IS RELATED TO AN INTERNAL WIRE BREAK INSIDE WIRE HARNESS INSULATION TO X411 CONNECTOR. MODELS 2010-2 ( NHTSA ITEM NUMBER - 10045959 )