Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 11 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, and 2002 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. Operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, and temperature that you observed. This will isolate when the DTC failed. For an intermittent condition, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.

An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provide the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination.