GM Service Manual Online
For 1990-2009 cars only
  1. Inspect the tire pressure.
  2. Adjust the tire pressure as noted on the tire placard.
  3. Road test the vehicle in order to verify the problem.
  4. Perform the following steps in order to test each strut:
  5. 4.1. Test each strut in turn by quickly pushing down, then lifting up the corner of the bumper nearest the strut. Use the same amount of effort on each test.
    4.2. Observe the resistance on compression and rebound for each test. You should notice the most resistance on the rebound stroke.
    4.3. Compare the resistance with a similar vehicle having acceptable ride quality. Both vehicles should provide the same feeling of resistance.
    4.4. Replace the struts as a pair if you notice is a substantial difference between the struts of the two vehicles or if rebound is excessive.