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DTC P0671, P0672, P0673, or P0674

DTC P0671, P0672, P0673, or P0674

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 Malfunction

DTC P0672 00

Cylinder 2 Glow Plug Control Circuit Malfunction

DTC P0673 00

Cylinder 3 Glow Plug Control Circuit Malfunction

DTC P0674 00

Cylinder 4 Glow Plug Control Circuit Malfunction

Circuit/System Description

This DTC applies to internal microprocessor integrity conditions within the glow plug control module.

Conditions for Running the DTC


• The ignition is ON.

• The battery voltage is between 9-16 V.

• The DTC runs once per ignition cycle when the above condition is met.


Conditions for Setting the DTC

The ECM detects a glow plug control module malfunction.

Action Taken When the DTC Sets

DTC P0671, P0672, P0673 and P0674 are Type C DTC.

Conditions for Clearing the DTC

DTC P0671, P0672, P0673 and P0674 are Type C DTC.

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

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 connector at the K34 Glow Plug Control Module.

2. Test for less than 5 Ω of resistance between the ground circuit terminal 3 and ground.

3. If greater than the specified range, test the ground circuit for an open/high resistance.

4. Test for greater than 0.3 Ω of resistance between each of the glow plug circuit terminals and ground.

• Glow Plug 1 circuit terminal 3

• Glow Plug 2 circuit terminal 1

• Glow Plug 3 circuit terminal 4

• Glow Plug 4 circuit terminal 6

5. If less than the specified range, test the glow plug circuit for a short to ground.

6. Ignition ON, verify a test lamp illuminates between the ignition voltage circuit terminal 4 and ground.

7. If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance.

8. If all circuits test normal, replace the K34 Glow Plug Control Module.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Glow Plug Control Module Replacement

• Glow Plug Replacement

• Control Module References for ECM replacement, setup, and programming