GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle
    • Review Strategy Based Diagnosis
    •  Diagnostic Procedure Instructions

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition voltage - fuse to splice

1

2

--

--

Ignition voltage - splice to injector

1

P0201 00, P0202 00, P0203, 00 or P0204 00

--

--

Fuel injector 1 control

P0261 00

P0201 00

P026 00

--

Fuel injector 2 control

P0264 00

P0202 00

P0265 00

--

Fuel injector 3 control

P0267 00

P0203 00

P026 00

--

Fuel injector 4 control

P0270 00

P0204 00

P0271 00

--

1. Open fuse, cranks no start

2. Cranks no start

Circuit/System Description

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References

Special Tools

EL-35616-E M-Approved Terminal Test Kit includes J-35616-200 Test Light -Probe Kit

For equivalent regional tools, refer to LINK.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate fuel injector listed below:
  2. • Q17A Fuel Injector 1
    • Q17B Fuel Injector 2
    • Q17C Fuel Injector 3
    • Q17D Fuel Injector 4
  3. Ignition ON, verify that a test lamp illuminates between the appropriate Q17 Fuel Injector ignition circuit terminal 1 or circuit terminal A and ground.
  4. If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the Q17A Fuel Injector.
  5. Ignition OFF, connect a J-35616-200 Test Light -Probe Kit between the K20 Engine Control Module (ECM) control circuit terminal 2 or B and the ignition circuit terminal 1 or circuit terminal A of each Q17 Fuel Injector one at a time.
  6. Engine cranking, the test lamp should flash for each injector.
  7. If the test lamp is always ON, test the appropriate K20 Engine Control Module (ECM) control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).
    If the test lamp is always OFF, test the appropriate K20 Engine Control Module (ECM) control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).
  8. If all circuits test normal, test or replace the appropriate Q17D Fuel Injector. Refer to Fuel Injector Diagnosis

Repair Instructions

Perform the Diagnostic Repair Verification

    • Link (Fuel Injector Replacement)
    •  Control Module References