Circuit/System Testing
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- Crank the engine for 15 seconds.
- Observe the vehicle DTC information with a scan tool.
- If any DTCs are set, then repair those DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- With the ignition ON and the engine OFF, test the fuses that are supplied ignition 1 voltage by the powertrain relay. The test lamp should illuminate ON for each test point of the fuses.
- If the test lamp does not illuminate on, for at least one test point of each fuse, refer to DTC P0685, P0689, or P0690 .
- Crank the engine for 15 seconds. Observe the engine speed parameter with a scan tool.
- If engine RPM is not indicated, refer to DTC P0335 or P0336 .
- Install a spark plug tester onto one ignition module/coil assembly, on each bank of the engine.
- Observe both spark plug testers.
- Crank the engine for 15 seconds. The ignition coil secondary voltage should be observed across the gap of both spark plug testers.
- If the ignition coil secondary voltage is not observed, is inconsistent, or weak on either spark plug tester, refer to Electronic Ignition (EI) System Diagnosis .
- With the ignition ON and the engine OFF, command the fuel pump ON and OFF with the scan tool. The fuel pump should energize when commanded ON, and de-energize when commanded OFF.
- If the fuel pump does not turn ON and OFF, refer to Fuel Pump Electrical Circuit Diagnosis .
- Turn OFF the ignition.
- Install the J 34730-1A Fuel Pressure Gage. See Special Tools . With the ignition ON and the engine OFF, command the fuel pump ON several times with the scan tool. Refer to Fuel System Diagnosis for the fuel pressure specification.
- Inspect for the following conditions:
- Compare the actual engine coolant temperature to the ECT parameter
- Filter and air intake system for restrictions and obstructions
- Test the fuel for contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Inspect the spark plugs-Refer to Spark Plug Inspection .
- Test the exhaust system for restrictions-Refer to Restricted Exhaust .
- Engine mechanical conditions, such as worn timing chain, sprocket gears, low compression, etc-Refer to Engine Compression Test .
IMPORTANT:
An erratic or weak spark is considered a no spark condition.