If you need to calibrate a brake position sensor on your GMC Acadia, here's what you'll need to do:
1. Make sure the vehicle is parked on level ground and that the brakes are cooled down before beginning.
2. Locate the brake position sensor (it will be on or near the brake pedal) and disconnect the electrical connector.
3. Use a multimeter to measure the resistance between the two terminals on the sensor (the resistance should be within 50-200 ohms). If it's not within that range, replace the sensor.
4. Reconnect the electrical connector and pump the brakes a few times to seat the new sensor in place. Test drive the vehicle to make sure everything is working properly.