First make sure car is empty. On the UI go to parameter 5-1 to display load %. Adjust the offset potentiometer on the loadweigher board until 5-1 reads 0. Now, load car with full load and adjust the gain potentiometer until 5-1 reads 100. When weight is removed from the car, verify 5-1 is now displaying 0 again...+/-3%. If it's within 3% you're done, if not...start over and do once more. Let me know if you need anymore help.