Understand and Verify the Customers Concern. The first part of this step is to obtain as much information as possible from the customer. Are there aftermarket accessories on the vehicle- When does the condition occur- Where does the condition occur- How long does the condition last- How often does the condition occur- In order to verify the concern, the technician should be familiar with the normal operation of the system.
The following preliminary inspections/tests must be performed:
- Ensure that the battery is fully charged.
- Ensure that the battery cables are clean and tight.
- Inspect for any open fuses.
- Ensure that the grounds are clean, tight, and in the correct location.
- Inspect for aftermarket devices that could affect the operation of the system.
- Search for applicable service bulletins.
- With the ignition OFF, remove the fuel pump relay to disable fuel supply.
- Crank the engine and test for a spark on each cylinder spark plug wire using a spark tester tool.
- Ground the companion cylinder spark plug wire of each cylinder when it is tested.
- If there is no spark on any of the cylinders, test the ignition voltage circuit of the ICM for an open/high resistance or short to ground, or test the ground circuit of the ICM for an open/high resistance, or a faulty ICM.
- The wire circuit resistance should measure less than 3 ohms.
- If spark is present on one or more of the cylinders, inspect and test the spark plug wires for arching, cuts, rubbing on other components, and proper resistance.
- Check ICM operation.