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DTC P1248, P1249, P124A, or P124B - LNP or LNQ

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 P1248 00: Cylinder 1 Injector High Control Circuit Shorted to Control Circuit

DTC P1249 00: Cylinder 2 Injector High Control Circuit Shorted to Control Circuit

DTC P124A 00: Cylinder 3 Injector High Control Circuit Shorted to Control Circuit

DTC P124B 00: Cylinder 4 Injector High Control Circuit Shorted to Control Circuit

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Fuel Injector Positive Voltage Control Group 1

P2147 00

P0201 00, P0204 00

P2148 00

P2148 00

Fuel Injector Positive Voltage Control Group 2

P2150 00

P0202 00, P0203 00

P2151 00

P2149 00

Fuel Injector 1 Control

-

P0201 00

-

-

Fuel Injector 2 Control

-

P0202 00

-

-

Fuel Injector 3 Control

-

P0203 00

-

P124A 00

Fuel Injector 4 Control

-

P0204 00

-

P124B 00

Circuit/System Description

The engine control module (ECM) supplies voltage to each fuel injector on the injector positive voltage control circuits. The ECM energises 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 two groups:

    • Group 1 - Injectors 1 and 4
    • Group 2 - Injectors 2 and 3

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

Conditions for Running the DTC

    • The engine is running.
    • The ECM monitors for a condition once per camshaft revolution.

Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match.

Action Taken When the DTC Sets

DTCs P1248 00, P1249 00, P122A 00 and P122B 00 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P1248 00, P1249 00, P122A 00 and P122B 00 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 Verification

  1. Ignition ON, observe the DTC information with a scan tool. DTCs P2147 00, P2148 00, P2150 00 or P2151 00 should not set.
  2. If any DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  3. 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 are captured in the freeze frame/failure records Data List.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the affected fuel injector.
  2. Ignition ON, test for 2.0-2.5 V between the control circuit terminal 1 and ground.
  3. If less than the specified range, test the control circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
    If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
  4. Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module.
  5. Test for less than 5 Ω between the affected fuel injector low control circuit terminal 2 and the K20 Engine Control Module terminal as listed below:
  6. • Terminal 26 for injector 1
    • Terminal 74 for injector 2
    • Terminal 75 for injector 3
    • Terminal 25 for injector 4
    If greater than the specified range, test the low control circuit for an open/high resistance
  7. If all circuits test normal, perform the Component Testing before replacing the K20 Engine Control Module.

Component Testing

Static Test

  1. Disconnect the harness connector at the affected fuel injector.
  2. Note: The DMM and test leads must be calibrated to 0 Ω in order to prevent misdiagnosis.

  3. Test for 0.2-0.7 Ω between the low control terminal 2 and the high control terminal 1.
  4. If not within the specified range, replace the fuel injector.
  5. Test for infinite resistance between each terminal and ground.
  6. If not the specified value, 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, programming and setup
   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved