Diagnostic Aids

WARNING: This page is about a different car, the 2003 Chevrolet Corvette. 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.

Excessive vibration from sources other than the engine could cause DTC P0300 to set. The following are possible sources of vibration:
1. Variable thickness brake rotor.
2. Drive shaft not balanced.
3. Worn or damaged accessory drive belt.
There may be more or less cylinders actually misfiring than indicated by the scan tool.
Spray water on the secondary ignition components using a spray bottle. Look and listen for arcing or misfiring.
If there are multiple misfires on only one bank, inspect the fuel injector and ignition coil, power and ground circuits for that bank.
For an intermittent condition, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.