TrailBlazer 4WD V8-5.3L VIN M (2006)
To control any contamination to the DoD hydraulic circuits, a small replaceable oil screen is located in the VLOM oil inlet passage, below the oil
pressure sensor. The oil pressure sensor is a 3-wire sensor which provides oil pressure information to the ECM.
During service, use extreme care in keeping the VLOM assembly free of any contamination or foreign material.
Engine Control Module (ECM)
The engine control module (ECM) is responsible for the management and control of all engine functions. Each ECM comes equipped with a specific
set of software/calibrations designed for that engine and vehicle application. The ECM will determine engine operating parameters, based upon
information from a network of switches, sensors, modules and communication with other controllers located throughout vehicle. Internal to the ECM
is an integrated circuit device called a low-side driver. The low-side driver is designed to operate internally, like an electronic switch. An individual
low-side driver controls each valve lifter oil manifold (VLOM) solenoid. When enabling conditions for V4 mode are met, the ECM will command the
low-side driver to ground each VLOM solenoid control circuit, in firing order sequence. Internal to the low-side driver is a fault detection circuit,
which monitors the solenoid control circuit for an incorrect voltage level. If an incorrect voltage level, such as an open, high resistance, short to
ground, or short to power, is detected, the low-side driver, along with the fault detection circuit, will communicate the condition to the central
processor in the ECM. The ECM will then command a return to V8 mode, set a corresponding DTC, and illuminate the malfunction indicator lamp
(MIL) on the instrument panel.
Displacement on Demand (DoD) Inhibit Reasons
Listed below are the powertrain conditions that will inhibit V4 mode, while operating under light load driving conditions:
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Engine manifold vacuum low
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Brake booster vacuum pressure low
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Accelerator pedal position rate of increase too high, electronic throttle control
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Accelerator pedal position too high, electronic throttle control
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Ignition voltage out of range
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Engine oil pressure out of range
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Engine oil temperature out of range
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Engine RPM out of range
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Transmission gear incorrect
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Transmission range incorrect
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Transmission gear shift in progress
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All cylinders activated via scan tool output control
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Minimum time in V8 mode not met
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Maximum V4 mode time exceeded
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Engine oil aeration present
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Decel fuel cutoff active
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Fuel shut-off timer active
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Minimum heater temp low, HVAC system
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Reduced engine power active, electronic throttle control
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Brake torque management active
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Axle torque limiting active
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Engine metal over temperature protection active
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Catalytic converter over temperature protection active
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Piston protection active, knock detected
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Hot coolant mode active
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Engine over speed protection active
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Fault Active or Fault Pending-displacement on demand (DoD) is disabled for the following faults:
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Manifold Absolute Pressure Sensor
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Brake Booster Vacuum Sensor
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Engine Oil Pressure Sensor
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Engine Coolant Temperature Sensor
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Vehicle Speed Sensor
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Crankshaft Position Sensor
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Engine Misfire Detected
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Displacement On Demand Solenoid Driver Circuit
The scan tool output control is used to deactivate half of the engine cylinders, V4 mode, by commanding all of the solenoids ON, or deactivate one
cylinder switching to a V7 mode, by commanding ON one solenoid. Listed below are the powertrain conditions that will inhibit V4 mode, or V7
mode, with the engine running, while using the scan tool output control function:
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Engine speed out of range
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Manifold absolute pressure (MAP) sensor fault
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Accelerator pedal position too high, electronic throttle control
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Piston protection active, knock detected
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Engine oil temperature out of range
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Engine oil pressure out of range
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Engine oil aeration present
