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DTC P0671, P0672, P0673, or P0674 - 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 P0671 00: Cylinder 1 Glow Plug Control Circuit

DTC P0672 00: Cylinder 2 Glow Plug Control Circuit

DTC P0673 00: Cylinder 3 Glow Plug Control Circuit

DTC P0674 00: Cylinder 4 Glow Plug Control Circuit

Circuit/System Description

The glow plug controller is a solid state device which operates the glow plugs. The temperature and the power consumption is controlled between the engine control module (ECM) and the glow plug controller within a wide range to suit the engine pre-heating requirements. The ECM controls the glow plug module with a pulse-width modulated (PWM) control circuit. The glow plug initial ON time will vary based on the system voltage and temperature. Lower temperatures cause longer ON times.

Conditions for Running the DTC
    • The ignition is ON or the engine is running.
    • The ignition voltage is less than 16 V.
    • These DTCs run once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM detects an open or a short to ground on a glow plug control circuit for greater than 6 s.

Action Taken When the DTC Sets

DTCs P0671 00, P0672 00, P0673 00, P0674 00 are Type C DTCs.

Conditions for Clearing the DTC

DTCs P0671 00, P0672 00, P0673 00, P0674 00 are Type C 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 P0671 00, P0672 00, P0673 00, or P0674 00 should not set.
  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
  1. Ignition OFF, disconnect the harness connectors at the K34 Glow Plug Control Module.
  2. Test for 0.5-1.5 Ω between the appropriate glow plug control circuit terminal listed below and ground.
    3. • E12A Glow Plug 1 circuit terminal 3 X2
    • E12B Glow Plug 2 circuit terminal 1 X2
    • E12C Glow Plug 3 circuit terminal 4 X2
    • E12D Glow Plug 4 circuit terminal 6 X2
    ⇒If less than the specified range, test the control circuit for a short to ground. If the circuit tests normal, replace the appropriate glow plug.
    ⇒If greater than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the appropriate glow plug.
  3. If all circuits test normal, test or replace the K34 Glow Plug Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Glow Plug Replacement
    •  Glow Plug Controller Replacement
   


© Copyright Chevrolet. All rights reserved
   


© Copyright Chevrolet. All rights reserved