Diagnostic Aids

WARNING: This page is about a different car, the 2002 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.

For any test that requires probing the PCM or probing a component harness connector, use the J 35616-A connector test adapter kit. Using this kit prevents damage to the harness and component terminals.

Running the vehicle out of fuel causes sufficient misfire to set DTC P0300. A vehicle that is out of fuel may have DTC P0461 and DTC P1431 also set.
A restricted fuel filter can cause sufficient misfire to set DTC P0300.
A misfire that only occurs during certain conditions may be difficult to locate. Observe the Freeze Frame and the Failure Records in order to determine when the DTC set.
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.
A misfire may not be apparent at idle. The misfire may only occur above idle during a load. Road-test the vehicle, and monitor the misfire current counters.
For an intermittent condition, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.