How to Use The Diagnostic Procedure

Become familiar with the terms. Use the Glossary of Terms to find the descriptive name of conditions not encountered before. Proceed to identifying the condition and locate the proper diagnosis. By beginning at that point, most other systems in the vehicle have been eliminated. Follow the steps within the test. Always follow each diagnostic procedure step exactly and make notes along the way to recall important findings later.

Diagnostic Procedure

1. Customer Interview
Interview the customer. Customer feedback can supply information that could be helpful in diagnosing the concern. Ask questions like:
- When is the concern present (at idle or while driving)?
- Where does the concern appear to be coming from?
- How long has the concern been there? Has it steadily become worse?
- When did the concern start?

2. Duplicate the Noise Concern
A few ideas on how to duplicate the noise are:
- Is the noise heard while bouncing the bumper of the vehicle?
- Or, is the noise only heard while driving over rough road surfaces?
- Or, is the noise only heard while braking?
- Or, is the noise only heard when driving, or while parked?
Typically, front underbody noise is heard while doing the static bounce test (bouncing the bumper or the vehicle). If the noise can not be duplicated with the static bounce test, or during low speed turning maneuvers, it is most likely not suspension related.

3. Isolate the Noise Concern
If the noise can be duplicated by the static bounce test, one of the following methods will help to locate the problem while doing the static bounce test.
- Use a stethoscope or chassis ears to determine the area of the chassis that the noise appears to be coming from.
- Place your hand on the coil spring, radius arm, or stabilizer bar. This method is sometimes misleading as the vibrations may carry from one suspension component to another.

4. Inspecting the Vehicle
While inspecting the vehicle in the general area of the source of the noise, look for the following:
- Loose fasteners.
- Worn/broken parts.
- Excessive dirt/rust accumulation.
- Signs of leaking fluid.

5. Repair of the Vehicle
Use the symptom chart to find which pinpoint test, actions or other section(s) to refer to. Symptom Related Diagnostic Procedures

6. Test Drive the Vehicle
Repeat the method used to duplicate the problem to verify that the noise has been repaired.

7. Follow-Up With the Customer
Follow-up with the customer about two weeks after the repair is performed to assure that the noise was correctly identified and repaired.