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.

DTC Descriptors

DTC P1224: Fuel Injector 1 Control Circuit Shorted

DTC P1227: Fuel Injector 2 Control Circuit Shorted

DTC P122A: Fuel Injector 3 Control Circuit Shorted

DTC P1233: Fuel Injector 4 Control Circuit Shorted

DTC P1236: Fuel Injector 5 Control Circuit Shorted

DTC P1239: Fuel Injector 6 Control Circuit Shorted

DTC P1242: Fuel Injector 7 Control Circuit Shorted

DTC P1247: Fuel Injector 8 Control Circuit Shorted

Diagnostic Fault Information

Fuel Injector Circuits

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Fuel Injector Positive Voltage Control Group 1

P2146

P2146

P0201, P0204¹

P1233, P1224, P2146

--

Fuel Injector Positive Voltage Control Group 2

P2149

P2149

P0206, P0207¹

P1239, P1242, P2149

--

Fuel Injector Positive Voltage Control Group 3

P2152

P2152

P0202, P0205¹

P1227, P1236, P2152

--

Fuel Injector Positive Voltage Control Group 4

P2155

P2155

P0203, P0208¹

P122A, P1247, P2155

--

Fuel Injector 1 Control

P1233, P2146

P2146

P0201

P1224, P2146

--

Fuel Injector 2 Control

P1236, P2152

P2152

P0202

P1227, P2152

--

Fuel Injector 3 Control

P1247, P2155

P2155

P0203

P122A, P2155

--

Fuel Injector 4 Control

P1224, P2146

P2146

P0204

P1233, P2146

--

Fuel Injector 5 Control

P1227, P2152

P2152

P0205

P1236, P2152

--

Fuel Injector 6 Control

P1242, P2149

P2149

P0206

P1239, P2149

--

Fuel Injector 7 Control

P1239, P2149

P2149

P0207

P1242, P2149

--

Fuel Injector 8 Control

P122A, P2155

P2155

P0208

P1247, P2155

--

¹ Misfire DTCs may also set.

Circuit/System Description

The engine control module (ECM) supplies voltage to each fuel injector on the injector positive voltage control circuits. The ECM energizes each fuel injector by grounding the control circuit of that fuel injector. The ECM monitors the status of the injector positive voltage control circuits and the fuel injector control circuits. The injectors are separated into the following four groups:

    • Group 1--DTC P2146 with injectors 1 and 4
    • Group 2--DTC P2149 with injectors 6 and 7
    • Group 3--DTC P2152 with injectors 2 and 5
    • Group 4--DTC P2155 with injectors 3 and 8

When a fuel injector circuit condition is detected by the ECM, the affected fuel injectors will be disabled and may disable the affected group of fuel injectors.

Conditions for Running the DTC

    • The engine is running.
    • The charging system voltage is between 10-18 volts.

Conditions for Setting the DTC

    • The ECM injector output driver detects an incorrect current on a fuel injector circuit.
    • The condition exists for 1 second.

Action Taken When the DTC Sets

DTCs P1224, P1227, P122A, P1233, P1236, P1239, P1242 and P1247 are Type A DTCs.

Conditions for Clearing the MIL/DTC

DTCs P1224, P1227, P122A, P1233, P1236, P1239, P1242 and P1247 are Type A DTCs.

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

Important: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Observe the DTC information with a scan tool. If DTC P2146, P2149, P2152 or P2155 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

One Fuel Injector DTC Sets

  1. Disconnect the affected fuel injector connector.
  2. Turn ON the ignition with the engine OFF.
  3. Connect a test lamp between the affected fuel injector control circuit and a ground. The test lamp should not illuminate.
  4. If the test lamp illuminates, test the fuel injector control circuit for a short to voltage.
  5. Connect a test lamp between the affected fuel injector control circuit and battery voltage. The test lamp should not illuminate.
  6. If the test lamp illuminated, test the fuel injector control circuit for a short to ground.
  7. Test the affected group injector positive voltage control circuit for a short to ground or a short to voltage.
  8. Test the affected fuel injector for high resistance. Refer to Component Testing in this diagnostic.
  9. If the circuits tested normal, replace the ECM.

Component Testing

  1. Disconnect the connector of the fuel injector to be tested.
  2. Connect a DMM between the terminals of the fuel injector and measure the resistance. The resistance should be 0.2-0.3 ohms.
  3. If the resistance is more than 0.2-0.3 ohms resistance, replace the fuel injector.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Fuel Injector Replacement
    •  Control Module References for ECM replacement, programing, and setup