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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Envoy - 2WD 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC P3400

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 Descriptor

DTC P3400: Cylinder Deactivation System Performance

Circuit/System Description

The Cylinder Deactivation System Performance diagnostic is a test of the internal mechanical condition of the engine, during operation in V4 mode. The control module determines the internal mechanical condition of the engine through the actual measured values of the mass airflow (MAF) sensor, the intake manifold absolute pressure (MAP) sensor, and the throttle position (TP) sensor. The actual measured values of the 3 sensors are then compared to the calculated values for V4 mode, stored in the engine control module (ECM). If the measured values are incorrect for V4 mode, the ECM will set DTC P3400, and will return to V8 mode operation.

Conditions for Running the DTC
    • DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0119, P0335, and P0336 are not set.
    • The engine speed is between 450-6,400 RPM.
    • The IAT Sensor parameter is between -7 and +125°C (+19 and +257°F).
    • The ECT Sensor parameter is between 70- 125°C (158-257°F).
    • Time in V8 mode is more than 2 seconds.
    • Time in V4 mode is more than 2 seconds.
    • This DTC runs continuously within the enabling conditions.

Conditions for Setting the DTC
    • The control module detects that the actual measured values from the MAF sensor, MAP sensor, and TP sensor, is not within the range of the calculated values for V4 mode.
    • The above condition is met for more than 100 milliseconds.

Action Taken When the DTC Sets
    • DTC P3400 is a Type B DTC.
    • The engine will return to V8 mode.

Conditions for Clearing the DTC

DTC P3400 is a Type B DTC.

Diagnostic Aids
    • This DTC will not set during engine idling conditions. The vehicle will need to be driven for the DTC to set.
    • This test procedure requires that the vehicle battery has passed a load test and its completely charged. Refer to Battery Inspection/Test .
    • The valve lifter oil manifold (VLOM) solenoids are assigned to the following engine cylinders:
       - Solenoid #1--Cylinder #1
       - Solenoid #2--Cylinder #4
       - Solenoid #3--Cylinder #6
       - Solenoid #4--Cylinder #7

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views
    •  Electrical Center Identification Views

Description and Operation

Cylinder Deactivation (Active Fuel Management) System Description

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

Mechanical Information Reference

Cylinder Deactivation (Active Fuel Management) System Diagnosis

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification
  1. Start and idle the engine.
  2. Allow the engine to reach normal engine operating temperature. The engine should idle smoothly, without any misfires. If the engine misfires, refer to DTC P0300-P0308 .
  3. Monitor the cylinder deactivation system data parameters with a scan tool.
  4. Road test the vehicle under light throttle and load conditions that will allow the engine control module (ECM) to command V4 mode. If all enabling conditions are met for cylinder deactivation, and if no internal engine hydraulic/mechanical fault conditions are present, the ECM will continue with V4 mode operation.
    5. ⇒If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records data list. Another option is to refer to Testing for Intermittent Conditions and Poor Connections .

Circuit/System Testing

Electrical System Testing

  1. If DTCs P3401, P3425, P3441, or P3449 are set, refer to DTC P3401, P3425, P3441, or P3449 .
  2. Ignition ON, the engine OFF, command each VLOM solenoid ON and OFF using the scan tool output control function. While standing next to the engine compartment, you should be able to hear the solenoid energize and de-energize with each scan tool output control command.
⇒If you cannot hear each solenoids energize and de-energize, then refer to Cylinder Deactivation (Active Fuel Management) System Diagnosis .

Mechanical System Testing

Refer to Cylinder Deactivation (Active Fuel Management) System Diagnosis .

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.