Heated Oxygen Sensor (Ho2S) Heater Control Block Diagram; Heated Oxygen Sensor (Ho2S) Heater Control Operation; Operation Conditions; A/C Cut-Off Control Outline - Mazda RX-8 2004 Service Highlights

HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL BLOCK DIAGRAM

• The PCM determines the engine conditions based on input signals and sends an operation signal to the front or
rear HO2S.
ECT SENSOR
IAT SENSOR
MAF SENSOR
BARO SENSOR
ECCENTRIC SHAFT
POSITION SENSOR
BATTERY
IGNITION SWITCH
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HEATED OXYGEN SENSOR (HO2S) HEATER CONTROL OPERATION

Operation Conditions

• The PCM operates the HO2S when the following conditions are met.
HO2S
• 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.
Front
• Battery positive voltage is 9 V or more and less
than 16 V.
• MAF sensor is normal (no DTC is stored in
PCM).
• 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
Rear 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.
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A/C CUT-OFF CONTROL OUTLINE

• 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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CONTROL SYSTEM
PCM
Activation condition
FRONT HO2S HEATER
REAR HO2S HEATER
Drive signal
• The PCM outputs a duty signal.
• The element temperature is measured by the
impedance of the HO2S and a duty ratio is
determined.
• The PCM outputs a duty signal. However the
duty signal is either 100% or 0%.
CHU014000140S40
01–40
CHU0140S031
CHU014000140S41
CHU014000140S42
01–40–35