Cylinder Deactivation Inhibit Reasons

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Listed below are the powertrain conditions that will inhibit V4 mode, while operating under light load driving conditions:

Engine manifold vacuum low
Brake booster vacuum pressure low
Accelerator pedal position rate of increase too high, electronic throttle control
Accelerator pedal position too high, electronic throttle control
Ignition voltage out of range
Engine oil pressure out of range
Engine oil temperature out of range
Engine RPM out of range
Transmission gear incorrect
Transmission range incorrect
Transmission gear shift in progress
All cylinders activated via scan tool output control
Minimum time in V8 mode not met
Maximum V4 mode time exceeded
Engine oil aeration present
Decel fuel cutoff active
Fuel shut-off timer active
Minimum heater temp low, HVAC system
Reduced engine power active, electronic throttle control
Brake torque management active
Axle torque limiting active
Engine metal over temperature protection active
Catalytic converter over temperature protection active
Piston protection active, knock detected
Hot coolant mode active
Engine over speed protection active
Fault Active or Fault Pending-cylinder deactivation is disabled for the following faults:
- Manifold Absolute Pressure Sensor
- Engine Oil Pressure Sensor
- Engine Coolant Temperature Sensor
- Vehicle Speed Sensor
- Crankshaft Position Sensor
- Engine Misfire Detected
- Cylinder Deactivation 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:

Engine speed out of range
Manifold absolute pressure (MAP) sensor fault
Accelerator pedal position too high, electronic throttle control
Piston protection active, knock detected
Engine oil temperature out of range
Engine oil pressure out of range
Engine oil aeration present
Engine metal over temperature protection active
Accelerator pedal position rate of increase too high, electronic throttle control
Cylinder deactivation solenoid driver circuit fault
Engine coolant temperature sensor fault
Catalytic converter over temperature protection active
Brake booster vacuum pressure low
Axle torque limiting active
Brake torque management active
Vehicle speed sensor fault
Engine coolant temperature too high
Engine not running
Vehicle speed not zero
Engine coolant temperature low
Reduced Engine Power Active, electronic throttle control
Transmission gear incorrect
Transmission range incorrect
Ignition voltage out of range
Maximum V4 mode time exceeded

Listed below are the powertrain conditions that will inhibit a cylinder deactivation solenoid from being energized, with the ignition ON and the engine OFF, while using the scan tool output control function:

Engine speed not zero
Vehicle speed not zero
Transmission not in park or neutral
Ignition voltage out of range

For the system description covering the hydraulic/mechanical system of cylinder deactivation, refer to Cylinder Deactivation (Active Fuel Management) System Diagnosis .