• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

The engine control module (ECM) supplies voltage to each fuel injector on the injector high voltage supply circuits. The ECM energizes each fuel injector by grounding the high voltage control circuit of the fuel injector. The ECM monitors the status of the injector high voltage supply circuits and the injector high voltage control circuits. When a fuel injector circuit condition is detected by the ECM, the affected fuel injector(s) is disabled.

• Performing the fuel injector coil test may help isolate an intermittent condition. Refer to Fuel Injector Solenoid Coil Test.
• If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool Injector Control Circuit Status parameters. An Injector Control Circuit Status parameter will change from OK or Not Run to Malfunction if there is a condition with the circuit or a connection.

Engine Controls Schematics

Component Connector End Views

Fuel System Description

Control Module References for scan tool information

1. Engine idling.
2. Verify the scan tool Cylinder 1–6 Current Misfire Counter parameters do not increment.
• If the Cylinder 1–6 Current Misfire Counters increment

  Refer to Circuit/System Testing.

• If the Cylinder 1–6 Current Misfire Counters do not increment
3. Verify the scan tool Cylinder 1–6 Injector Control Circuit Status parameters display OK.
• If the Cylinder 1–6 Injector Control Circuit Status parameters do not display OK

  Refer to Circuit/System Testing.

• If the Cylinder 1–6 Injector Control Circuit Status parameters display OK
4. All OK.

1. Ignition OFF, all vehicle systems OFF. Disconnect the X3 harness connector at the K20 Engine Control Module. It may take up to 2 min for all vehicle systems to power down.
2. Test for infinite resistance between the appropriate Q17 Fuel Injector control + circuit and ground.
• If less than infinite resistance
1. Disconnect the harness connector of the Q17 Fuel Injector.
2. Test for infinite resistance between the Q17 Fuel Injector control + circuit and ground.
• If infinite resistance
3. Test for infinite resistance between the Q17 Fuel Injector control − circuit and ground.
• If less than infinite, repair the short to ground in the circuit.
• If infinite, replace the Q17 Fuel Injector.
• If infinite resistance
3. Ignition ON.
4. Test for less than 1 V between the Q17 Fuel Injector control + circuit and ground.
• If 1 V or greater
1. Disconnect the harness connector of the Q17 Fuel Injector, ignition ON.
2. Test for less than 1 V between the Q17 Fuel Injector control + circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, repair the short to voltage on the control − circuit.
• If less than 1 V
5. Ignition OFF.
6. Test for less than 3 Ω between the Q17 Fuel Injector control + circuit and control − circuit.
• If 3 Ω or greater
1. Disconnect the harness connector of the Q17 Fuel Injector.
2. Test for less than 2 Ω on the control + circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω
3. Test for less than 2 Ω on the control − circuit end to end.
• If 2 Ω or greater, repair the open/high resistance in the circuit.
• If less than 2 Ω, replace the Q17 Fuel Injector.
• If less than 3 Ω
7. Replace the K20 Engine Control Module.

Perform the Diagnostic Repair Verification after completing the repair.

• Fuel Injector Replacement
• Control Module References for K20 Engine Control Module replacement, programming, and setup