Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

Crank the engine while observing the scan tool Vehicle DTC Information.
- If any of the following DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnose those DTCs: P0016, P0201-P0206, P0230, P0335, P0336, P0351-P0353, P0601, P0602, P0604, P0606, P0685, P0689, P0690, P1516, P2610.
Ignition OFF for 90 seconds, determine the current vehicle testing altitude. Ignition ON, observe the scan tool MAP Sensor parameter. Compare the parameter to the Altitude Versus Barometric Pressure table. The MAP Sensor Pressure parameter should be within the specified range indicated in the table.
- If the reading is not correct for your altitude, diagnose the MAP sensor. Refer to DTC P0106 .
Verify the following scan tool parameters indicate OK when the engine is cranked:
- Cylinder 1-6 Injector Circuit Short to Ground Test Status
- Cylinder 1-6 Injector Circuit Open Test Status
- If the parameters do not indicate the specified values, refer to DTC P0201, P0202, P0203, P0204, P0205, or P0206 .
Verify the following scan tool parameters change from Not Run to OK, when the engine is cranked:
Cylinder 1-6 Injector Circuit Short to Volts Test Status
- If the parameters do not indicate the specified values, refer to DTC P0201, P0202, P0203, P0204, P0205, or P0206 .
Crank the engine while observing the scan tool engine speed parameter.
- If engine RPM is not indicated, refer to DTC P0335 .
Install a J 26792 HEI Spark Tester. See Special Tools .
Crank the engine while observing the spark tester. The spark tester should spark.
- If spark is not observed refer to Electronic Ignition System Diagnosis .
With the ignition ON and the engine OFF, test the fuses that are supplied by the powertrain relay for voltage.
- If the test lamp does not illuminate on at least one side of each fuse, refer to Engine Cranks But Does Not Run .

IMPORTANT: Additional DTCs may set when using the fuel pump output control.

Command the fuel pump ON and OFF. Fuel pump should energize when commanded ON and De-energize when commanded OFF.
- If the fuel pump does not respond refer to Fuel Pump Electrical Circuit Diagnosis .
Turn OFF the ignition.
Install the CH-48027 . Turn ON the ignition and command the fuel pump ON while observing the CH-48027 . The fuel pressure should be between 384-425 kPa (56-62 psi). See Special Tools .
- If the fuel pressure is not within 384-425 kPa (56-62 psi) refer to Fuel System Diagnosis .
Inspect for the following conditions:
- Compare the actual engine coolant temperature to the ECT parameter.
- Air filter and air intake system for restrictions and obstructions
- Test the fuel for ethanol content. Refer to Fuel Composition Diagnosis for 3.5L (RPO LZE), VIN Code K, E85 compatible engines only.
- Test the fuel for contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis for non-E85 vehicles.
- Inspect the spark plug and spark plug wires. Refer to Spark Plug Inspection and Spark Plug Wire Inspection .
- Test the exhaust system for restrictions. Refer to Restricted Exhaust .