GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • 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.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Ignition 1 Voltage-Fuse to Splice

¹

²

--

--

Injector 1 Voltage-Splice to Injector

¹

P0201, P0202, P0203, or P0204

--

--

Fuel Injector 1 Control

P0201

P0201

P0201

--

Fuel Injector 2 Control

P0202

P0202

P0202

--

Fuel Injector 3 Control

P0203

P0203

P0203

--

Fuel Injector 4 Control

P0204

P0204

P0204

--

¹Open fuse, Cranks no start

²Cranks no start

Circuit/System Description

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The control module 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

    •  Engine Controls Connector End Views
    •  Inline Harness Connector End Views

Electrical Information Reference

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

Scan Tool Reference

    •  Scan Tool Data Definitions
    •  Scan Tool Data List
    •  Scan Tool Output Controls

Special Tools

J 35616-200 Test Light Probe Kit

Circuit/System Verification

Key ON, observe the DTC information with a scan tool. DTC P0201, P0202, P0203, or P0204 should not be set.

Circuit/System Testing

  1. Ignition OFF, disconnect the C101 fuel injector multi-way connector.
  2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal A powertrain control module (PCM) harness side and ground.
  3. 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 fuel injector.
  4. Ignition OFF, connect a J 35616-200 Probe Kit between the ignition circuit terminal A and the control circuit PCM harness side, of the appropriate injector listed below:
  5. • Injector 1 terminal B
    • Injector 2 terminal C
    • Injector 3 terminal D
    • Injector 4 terminal E
  6. Engine cranking, the test lamp should flash for each injector.
  7. If the test lamp is always ON, test the appropriate control circuit for a short to ground. If the circuit tests normal, replace the PCM.
    If the test lamp is always OFF, test the appropriate control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the PCM.
  8. Ignition OFF, measure for 10-15 ohms on the engine harness side of C101 between the ignition circuit terminal A and the control circuit of the appropriate injector listed below:
  9. • Injector 1 terminal B
    • Injector 2 terminal C
    • Injector 3 terminal D
    • Injector 4 terminal E
    If the resistance is not within the specified range, test for a short to ground or an open/high resistance between C101 and the appropriate fuel injector harness connector. If the circuits test normal, test or replace the affected fuel injector.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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