Colorado 4WD V8-5.3L (2010)
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The proper spark plug gap and torque
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The proper ohm values for the spark plug wires
Refer to Ignition System Specifications (See: Specifications).
Circuit/System Testing
1. Turn OFF the ignition.
Important: This engine application uses 2 fuses, one for each bank, to supply ignition 1 voltage to the ignition module/coil assemblies and
also to the fuel injectors. A good indication that a fuse is open is that all 4 misfire counters are incrementing on one side of the engine
2. Inspect both fuses that supply ignition voltage to the ignition module/coils.
‹› If a fuse is open, test all 8 ignition voltage circuits to the ignition module/coils or the fuel injectors on that engine bank, for a short to ground.
3. Disconnect the 4 ignition module/coil, and the 4 fuel injector electrical connectors, for the engine bank that has the open fuse.
4. Replace the open fuse with a new fuse.
5. Ignition ON, engine OFF.
6. Reconnect each ignition module/coil, and fuel injector electrical connectors, one at a time.
‹› If the fuse opens when connecting an ignition module/coil or fuel injector electrical connector, then replace the component that caused the fuse
to open.
7. Ignition OFF, disconnect the appropriate ignition module/coil electrical connector.
8. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit and ground.
‹› If the test lamp does not illuminate test the ignition voltage circuit for an open/high resistance.
9. Verify that a test lamp illuminates between the ignition module/coil ground circuit and B+.
‹› If the test lamp does not illuminate, test the ignition module/coil ground circuit for an open/high resistance.
10. Inspect and measure the resistance of the spark plug wire. Refer to Spark Plug Wire Inspection (See: Ignition Cable/Testing and Inspection) and
Ignition System Specifications (See: Specifications).
‹› If the resistance value is not within the specified range, or does not pass the inspection, replace the spark plug wire.
11. Exchange the misfiring cylinder, ignition module/coil assembly with the ignition module/coil assembly from a non-misfiring cylinder.
12. Start and idle the engine. Observe the misfire counters on the scan tool.
‹› If the misfire transfers with the suspect ignition module/coil, then replace the ignition module/coil assembly.
‹› If the misfire does not transfer with the suspect ignition module/coil, then measure the resistance of the IC circuit. The IC circuit should
measure less than 5 ohms. If the circuit tests normal, replace the ECM.
Component Testing
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Use the Spark Plug Inspection procedure to verify the integrity of the spark plugs. Refer to Spark Plug Inspection (See: Spark Plug/Testing and
Inspection). Replace the spark plug if necessary.
Important: An erratic or weak spark is considered a no spark condition.
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Use the J 26792 to verify the output of each ignition module/coil. If no spark is detected across the gap of the spark plug tester, then replace the
ignition module/coil assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Computers and Control Systems/Testing and Inspection/Diagnostic Trouble Code Tests and
Associated Procedures/Verification Tests and Procedures) after completing the diagnostic procedure.
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Engine Control Module Programming and Setup (V8) (See: Testing and Inspection/Programming and Relearning/Engine Control Module
Programming and Setup) Engine Control Module Programming and Setup (2.9L and 3.7L) (See: Testing and Inspection/Programming and
Relearning/Engine Control Module Programming and Setup)
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Engine Control Module Replacement (See: Computers and Control Systems/Engine Control Module/Service and Repair)
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Ignition Coil Replacement (See: Service and Repair)
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Spark Plug Replacement (See: Spark Plug/Service and Repair)