Mazda RX-8 2004 - A;C Cut-Off Control Outline; Heated Oxygen Sensor (Ho2 S) Heater Control Block Diagram; Heated Oxygen Sensor (Ho2 S) Heater Control Operation; Operation Conditions

CONTROL SYSTEM
01–40–35
01–40
HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL BLOCK DIAGRAM
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• The PCM determines the engine conditions based on input signals and sends an operation signal to the front or
rear HO2S.
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HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION
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Operation Conditions
• The PCM operates the HO2S when the following conditions are met.
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A/C CUT-OFF CONTROL OUTLINE
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• The current application (energize/de-energize) to the A/C relay (magnetic clutch) is controlled according to the
engine operation conditions to prevent deterioration of engine performance, damage to the engine, and
deterioration of the A/C function.
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PCM
ECT SENSOR
IAT SENSOR
FRONT HO2S HEATER
BARO SENSOR
ECCENTRIC SHAFT
POSITION SENSOR
BATTERY
MAF SENSOR
REAR HO2S HEATER
IGNITION SWITCH
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HO2S Activation condition Drive signal
Front
• After engine start
• After the engine has started and a fixed period
of time has elapsed (the elapsed time period
after the engine starts is determined by ECT).
• ECT is 5°C {41°F} or more.
• Battery positive voltage is 9 V or more and less
than 16 V.
• MAF sensor is normal (no DTC is stored in
PCM).
• The PCM outputs a duty signal.
• The element temperature is measured by the
impedance of the HO2S and a duty ratio is
determined.
Rear
• Starter is off
• After engine start
• After the engine has started and a fixed period
of time has elapsed (the time period after the
engine starts lenghtens if the ECT falls below
0°C {32°F}.
• ECT is 10°C {50°F} or more.
• Battery positive voltage is 9 V or more and less
than 16 V.
• Charging efficiency is the fixed value or less, or
during fuel cut.
• The PCM outputs a duty signal. However the
duty signal is either 100% or 0%.