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VIN L




DTC P1224, P1227, P122A, P1233, P1236, P1239, P1242, or P1247

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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





Circuit/System Description

The engine control module (ECM) supplies a high voltage supply circuit and a high voltage control circuit for each fuel injector. The injector high voltage supply circuit and the high voltage control circuit are both controlled by the ECM. The ECM energizes each fuel injector by grounding the control circuit and supplying each fuel injector with up to 250 V and 20 A on the voltage supply circuit to activate the Piezo type fuel injectors. This is controlled by boost capacitors in the ECM. During the 250 V boost phase, the capacitor is used to charge the injector piezo stack, allowing for injector opening. The injector is then held open with this high voltage. At the end of the injection event the ECM closes the injector by discharging the injector piezo stack. The ECM monitors the status of the voltage supply and voltage control circuits. The injectors are separated into the following four groups:

* Group 1- injectors 1 and 4
* Group 2- injectors 6 and 7
* Group 3- injectors 2 and 5
* Group 4- injectors 3 and 8

When a fuel injector circuit fault condition is detected by the ECM, the specific fuel injector, or the two fuel injectors in the affected group may be disabled. DTCs for the injector and/or group may set.

Conditions for Running the DTC

* Engine speed is greater than 600 RPM.
* The charging system voltage is between 10-18 V.

Conditions for Setting the DTC

* The ECM injector output driver detects an incorrect current on a fuel injector circuit.
* The condition exists for less than 1 s.

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.

Diagnostic Aids

* The electronic control module (ECM) is sensitive to resistance on the injector circuits.
* Inspect each connector terminal for loose terminal fit or signs of fretting.
* Ensure that the ohm meter is zeroed before making any resistance checks.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Fuel System Description (Fuel System Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Engine Running, observe the following scan tool parameters.

* Cylinder 1 Injector Circuit Status
* Cylinder 2 Injector Circuit Status
* Cylinder 3 Injector Circuit Status
* Cylinder 4 Injector Circuit Status
* Cylinder 5 Injector Circuit Status
* Cylinder 6 Injector Circuit Status
* Cylinder 7 Injector Circuit Status
* Cylinder 8 Injector Circuit Status
Each parameter should display OK or Not Run.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Danger: Before working on any high voltage fuel injection system, be aware of the following procedures:


* Do not make contact with the fuel injection harness, engine control module (ECM), or fuel injectors while the ignition is ON or RUN positions.

* Wait 5 minutes after key OFF to allow the electronic control module (ECM) to discharge before attempting to disconnect or test engine control components.

* Do not use the electronic control module (ECM) case as a ground while jump starting.


Failure to follow the procedure exactly as written may result in serious injury or death.


1. 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 (Diagnostic Trouble Code (DTC) List - Vehicle).
2. Ignition OFF, disconnect the appropriate harness connector at the Q17 fuel injector.
3. Ignition ON, test for less than 1 V between the appropriate Direct Fuel Injector (DFI) High Control Supply circuit terminal 2 and ground.

• If greater than the specified value, repair the short to voltage in the appropriate Direct Fuel Injector (DFI) High Voltage Control circuit.

4. If all circuits test normal, replace the K20 engine control module.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for ECM replacement, programing, and setup

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