Vehicle Speed Limiter (At); Drive-By-Wire Relay Control Outline; Drive-By-Wire Relay Control Operation; Sequential Dynamic Air Intake System (S-Dais) Control Outline - Mazda RX-8 2004 Service Highlights

Cruise control function
• The cruise control includes accelerating, coasting, resume, tap-down, tap-up and downshift functions (AT).
Function List
Function
• When any of the following conditions are met while driving in cruise control and when the RESUME/
Accelerating
ACCEL switch is continuously pressed, the PCM gradually increases the set vehicle speed.
— Except during resume operation
— The RESUME/ACCEL switch is on one time or more during resume operation.
• When the SET/COAST switch is continuously pressed, the PCM gradually decreases the set
Coasting
vehicle speed.
• When the RESUME/ACCEL switch signal is input to the PCM during regular driving (cruise control
Resume
is stopped) and the previously set vehicle speed is stored in the PCM, the PCM sets the set vehicle
speed to the previously set vehicle speed and begins control.
• When all of the following conditions are met while driving in cruise control, the PCM decreases the
Tap down
set vehicle speed by 1.6 km/h {1 mph} and controls the throttle valve actuator.
— During cruise control
— RESUME/ACCEL switch off
— The RESUME/ACCEL switch switches from off to on
— When actual vehicle speed is lower (set vehicle speed −2 km/h {-1.2 mph})
• When all of the following conditions are met, the PCM increases the set vehicle speed by 1.6 km/h
Tap-up
{1 mph} and controls the throttle valve actuator so that the vehicle speed is close to the set vehicle
speed.
— During cruise control
— The RESUME/ACCEL switch switches from off to on
• When the following conditions are met, a downshift signal is sent to the TCM via CAN.
Downshift (AT)
— RESUME/ACCEL switch on
— Target vehicle acceleration is not reached

Vehicle Speed Limiter (AT)

• When the actual vehicle speed exceeds 200 km/h {124.3 mph}, the vehicle speed limiter controls the throttle
valve actuator so that vehicle speed is maintained at 200 km/h {124.3 mph} or less. It also reduces shock when
the vehicle speed reaches 200 km/h {124.3 mph} and prevents rapid temperature increase of the catalytic
converter during high speed.
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DRIVE-BY-WIRE RELAY CONTROL OUTLINE

• Supplies power to the drive-by-wire control.
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DRIVE-BY-WIRE RELAY CONTROL OPERATION

• When the main relay is on, the drive-by-wire relay also turns on. (See 01–40–10 MAIN RELAY CONTROL
OPERATION.)
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SEQUENTIAL DYNAMIC AIR INTAKE SYSTEM (S-DAIS) CONTROL OUTLINE

• Operates the SSV solenoid valve, the APV motor (13B-MSP (High Power)), the VDI solenoid valve, and the
VFAD solenoid valve (13B-MSP (High Power)) according to the engine speed range. As a result, torque and
output at all engine speed ranges have been improved.
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01–40–14
CONTROL SYSTEM
Contents
CHU014000140S13
CHU014000140S14
CHU014000140S15