Mazda X-5. Manual - part 41

CONTROL SYSTEM 

01–40–37

01–40

GENERATOR CONTROL OUTLINE [LF]

E5U014000000N52

• Idling stability and the corresponding load performance have been improved by optimum control of generator 

voltage according to engine operation and electrical load conditions.

• The PCM determines the engine operation and electrical load conditions based on the input signals from input 

devices shown in the figure below and controls the excitation time of the generator field coils.

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GENERATOR CONTROL BLOCK DIAGRAM [LF]

E5U014000000N53

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GENERATOR CONTROL OPERATION [LF]

E5U014000000N54

Determination of Field Coil Excitation Time

• By sending a duty signal to the power transistor 

built into the generator, the PCM increases and 
decreases the field coil excitation current.

• The field coil excitation current changes 

according to changes in the power transistor 
excitation time by changing the duty signal duty 
ratio. For example, when the battery voltage is 
low, the duty signal duty ratio sent to power 
transistor is higher, and the excitation current to 
the field coils increases.

Control

• To maintain optimum battery voltage, the PCM calculates the target excitation current based on the targeted 

generator current (target generated current) and the generator rotation speed at the time.

• The generator rotation speed is calculated from the generator pulley and crankshaft pulley ratios, and the 

engine speed.

• The PCM compares the target battery voltage (regulating voltage) calculated from the intake airflow 

temperature, engine speed and vehicle speed with the current battery voltage and, based on this difference, 
calculates the required generator current.

• When an electrical load is applied, the target rotation speed increases during idling because the battery voltage 

decreases due to the increased power consumption.

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PCM

IAT SENSOR

ECT SENSOR

CKP SENSOR

VEHICLE SPEED SIGNAL

GENERATOR (TERMINAL 
P: STATOR COIL)

BATTERY

FIELD COIL EXCITATION 
TIME

TARGET EXCITATION 
CURRENT

GENERATOR 
ROTATION 
SPEED

TARGET GENERATED 
CURRENT

TARGET BATTERY VOLTAGE 
(REGULATING VOLTAGE)

DEVIATION

CURRENT BATTERY 
VOLTAGE

GENERATOR (TERMINAL 
D: FIELD COIL)

E5U140ZT5011

1 CYCLE

EXCITATION TIME

C3U0140S029

CONTROL SYSTEM 

01–40–38

CONTROLLER AREA NETWORK (CAN) OUTLINE [LF]

E5U014000000N55

• The PCM sends and receives data to and from other modules via the CAN system. Refer to Section 09 for a 

detailed explanation of the CAN. (See 09–40–2 CAN SYSTEM DESCRIPTION.)

OUT: Output (sends signal)

IN: Input (receives signal)

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Signal

Multiplex module

PCM

TCM

ABS HU/CM 

or DSC HU/

CM

Keyless 

control 

module

Steering 

angle 

sensor

Instrument 

cluster

Engine speed

OUT

IN

IN (DSC)

IN

–

IN

Vehicle speed

OUT

IN

–

IN

–

IN

IN

OUT

–

–

Engine coolant temperature

OUT

IN

–

–

–

IN

Engine torque

OUT

IN

IN (DSC)

–

–

–

Accelerator pedal position

OUT

IN

IN (DSC)

–

–

–

TP

OUT

IN

IN  (DSC)

–

–

–

Intake air temperature

OUT

IN

–

–

–

–

Ignition timing

OUT

IN

–

–

–

–

Engine specification

OUT

–

IN

–

–

–

Brake pedal position

OUT

IN

–

–

–

–

Tire circumference (front/rear)

OUT

IN

IN

–

–

–

IN

–

OUT

Immobilizer related information

OUT

–

–

–

–

IN

IN

–

OUT

Travelled distance

OUT

–

–

–

–

IN

IN

OUT

–

Fuel injection amount

OUT

–

–

–

–

IN

MIL on request

OUT

–

–

–

–

IN

–

OUT

Generator warning light on request

OUT

–

–

–

–

IN

Cruise main/set indicator light on 
request

OUT

–

–

–

–

IN

AT gear position/selector lever 
position (AT)

IN

OUT

–

–

–

IN

ATF temperature (AT)

IN

OUT

–

–

–

–

Desired gear position (AT)

IN

OUT

IN (DSC)

–

–

–

TCC status (AT)

IN

OUT

IN (DSC)

–

–

–

AT warning light on request (AT)

IN

OUT

–

–

–

IN

Brake system status (EBD/ABS/
DSC)

IN

–

OUT

–

–

–

Wheel speed (LF, RF, LR, RR)

IN

–

OUT

–

–

–

Brake system warning light on 
request

–

–

OUT

–

–

IN

ABS warning light on request

–

–

OUT

–

–

IN

DSC indicator light on request

–

–

OUT (DSC)

–

–

IN

DSC OFF light on request

–

–

OUT (DSC)

–

–

IN

Security light on request

–

–

–

OUT

–

IN

Steering angle sensor status

–

–

IN (DSC)

–

OUT

–

Fuel tank level

IN

–

–

–

–

OUT

Parking brake position

–

–

IN (DSC)

–

–

OUT

CONTROL SYSTEM 

01–40–39

01–40

PCM FUNCTION [LF]

E5U014018880N01

Function List

• The control descriptions are as shown below.

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PCM CONSTRUCTION/OPERATION [LF]

E5U014018880N02

Structure

• A 120-pin (two-block) PCM connector has been adopted.

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Function

Description

Main relay control

When the ignition switch is turned to the ON position, the main relay turns on.

Drive-by-wire control

The drive-by-wire control calculates the optimum target throttle valve opening angle at all 
ranges of engine speeds and controls the throttle valve actuator.

Drive-by-wire relay control

Supplies power to the drive-by-wire control.

Variable intake air control

Switches energization of the variable shutter valve actuator according to engine speed to 
enhance the inertia charging effect.

Variable valve timing control

Changes the intake valve timing according to engine operation conditions to improve engine 
output, fuel economy and exhaust emission performance.

Fuel injection control

Performs optimum fuel injection according to engine operation conditions.

Fuel pump control

Performs energization of the fuel pump relay only when the engine is running (operates fuel 
pump) to improve stability and durability.

ESA control

Controls ignition to optimum timing according to engine operation conditions.

Evaporative purge control

An appropriate amount of evaporative gas is fed into the dynamic chamber by the driving of the 
purge solenoid valve according to the engine operation conditions to ensure driveability and 
prevent release of fuel vapor gas into the atmosphere.

EGR control

Adjusts the EGR to the optimum opening angle according to engine operation conditions.

HO2S heater control

Based on the control of the front and rear HO2S heater, a stabilized oxygen concentration is 
detected even at low exhaust gas temperature and feedback control of fuel injection even 
during cold engine start is made possible for improved cold temperature emission performance.

A/C cut-off control

The current application (energize/non-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.

Electrical fan control

Through cooling of the radiator and condenser by operation of the cooling fan according to 
vehicle conditions, engine reliability and cooling performance have been improved.

Starter cut-off control

Theft deterrence has been improved by controlling energization to the starter relay according to 
an engine stop request signal from the immobilizer system.

Generator control

Generator output is optimized according to the engine operation and electrical load conditions, 
ensuring idling stability and anti-load performance.

CAN

Used for communication with the EHPAS control module, ABS HU/CM, instrument cluster and 
DLC-2.

CONTROL SYSTEM 

01–40–40

NEUTRAL SWITCH FUNCTION [LF]

E5U014017640N01

• The neutral switch detects the neutral position of the gearshift lever.

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NEUTRAL SWITCH CONSTRUCTION/OPERATION [LF]

E5U014017640N02

• When the shift lever is in the neutral position, the contact closes (ON) and the PCM detects a voltage of 0 V. When 

the shift lever is not in the neutral position, the contact opens (OFF) and the PCM detects a voltage of 12 V.

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CLUTCH PEDAL POSITION (CPP) SWITCH FUNCTION [LF]

E5U014018660N01

• This switch determines whether the engine is under a load condition (condition in which the engine output is 

transmitted to the powertrain) or under a no-load condition (condition in which the engine output is not 
transmitted to the powertrain).

• Detects the clutch engagement condition.

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CLUTCH PEDAL POSITION (CPP) SWITCH CONSTRUCTION/OPERATION [LF]

E5U014018660N02

• When the clutch pedal is depressed, the contact closes (ON) and the PCM detects a voltage of 0 V. When the 

clutch pedal is not depressed, the contact opens (OFF) the PCM detects a voltage of 12 V.

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NEUTRAL SWITCH

PUSH ON

OTHER THEN 
NEUTRAL (OFF)

NEUTRAL (ON)

NEUTRAL (ON)

EXCEPT ABOVE

PCM

NO LOAD

LOAD

CPU

C3U0140S030

CPP SWITCH

PUSH OFF

PCM

CLUTCH PEDAL NOT 
DEPRESSED (OFF)

CLUTCH PEDAL NOT 
DEPRESSED (OFF)

CLUTCH PEDAL  
DEPRESSED (ON)

CLUTCH PEDAL  
DEPRESSED (ON)

NO LOAD

LOAD

CPU

C3U0140S031