Diagnostic Aids
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
While engine is operating, the exhaust system will become extremely hot. To prevent burns avoid contacting a hot exhaust system.
If the vehicle is equipped with a 6.6 L diesel engine do not perform this diagnostic. The exhaust system does not have a location for installing the J 35314-A See Special Tools and Equipment . Instead remove the suspect component, operate the vehicle, verify for improved performance. If performance is improved then replace the faulty component.