Diagnostic Aids

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Ensure that each fuel injector is connected to the proper fuel injector harness connector.
A misfire may only occur when the engine is operating under a load or when the engine is cold.
A high resistance condition on any ignition control (IC) circuit can cause an engine misfire DTCs P0300-P0308 to set without setting an IC circuit DTCs P0351-P0358.
This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test .
A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect the following for possible sources of vibration:
- A tire or wheel that is out of round or balance
- Variable thickness brake rotors
- An unbalanced drive shaft
- Certain rough road conditions
- A damaged accessory drive component or belt
- A damaged reluctor wheel
- The Crankshaft Position System Variation Learn procedure may need to be performed.