Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit/System Testing
2010 Chevrolet RV Cutaway 6.6 LSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Savana and 2010 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
- Crank the engine while observing the scan tool Vehicle DTC Information.
- If any of the following DTCs are set, diagnose these first: DTC P0117, P0118, P0122, P0123, P0201-P0208, P0222, P0223, P0335, P0336, P0351-P0358, P0513, P0562, P0563, P0601-P0604, P0606, P0607, P062F, P0633, P0685, P0690, P1516, P1631, P1682, or P2610. 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 while observing the scan tool engine speed parameter.
- Install a spark plug tester onto one ignition module/coil assembly, on each bank of the engine.
- Crank the engine while observing both spark plug testers. Both spark plug testers should spark.
- If spark is not observed, is inconsistent, or weak on either spark plug tester, refer to Electronic Ignition 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 System Diagnosis (w/o FPCM) or Fuel System Diagnosis (w/FPCM) .
- Turn OFF the ignition.
- Install the J 34730-1A Fuel Pressure Gauge. 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 (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) .
- 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 Symptoms - Engine Mechanical .
NOTE:
An erratic or weak spark is considered a no spark condition.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.