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. Verify that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Running the vehicle out of fuel causes sufficient misfire to set DTC P0300. A vehicle that is out of fuel may have fuel level DTCs also set.
A restricted fuel filter can cause sufficient misfire to set DTC P0300.
Excessive vibration from sources other than the engine can cause a misfire DTC. The following are possible sources of vibration:
1. Variable thickness brake rotor.
2. Drive shaft not balanced.
3. Certain rough road conditions.
Observe, if more then one cylinder is misfiring, the scan tool may only display one cylinder misfiring. This will not be apparent until the repair is completed. Also, if an ignition coil ground circuit is open for one side of the engine, the scan tool may only display 2 or 3 cylinders misfiring. Inspect the ground circuit for the ignition coil on the cylinder bank of the engine that has more then one cylinder misfiring.