Engine Control System (Lf, L3): Diagnosis Mazda 3 BL

PCM INSPECTION [LF, L3]

NEUTRAL SWITCH INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

Scheme 1

1. Remove the neutral switch. (See «NEUTRAL SWITCH REMOVAL/INSTALLATION [G35M-R]».)
2. Verify that the continuity between neutral switch terminals A and B is as indicated in the table. If it can be verified, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". If it cannot be verified, replace the neutral switch. CONTINUITY REFERENCE Measured condition Continuity Rod pushed Continuity detected Except above No continuity

Scheme 2

1. Disconnect the PCM connector.
2. Inspect the following wiring harness for an open or short circuit. (Continuity inspection)

Scheme 3

1. If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness. Neutral switch terminal A and PCM terminal 1X Neutral switch terminal B and body ground

CLUTCH PEDAL POSITION (CPP) SWITCH INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See «FOREWORD [LF, L3]».)

Scheme 4

1. Remove the CPP switch.
2. Verify that the continuity between CPP switch terminals A and B is as indicated in the table. If there is no malfunction, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". If there is any malfunction, replace the CPP switch. CONTINUITY REFERENCE Measurement condition Continuity Push the rod. No continuity Except above Continuity detected

Scheme 5

1. Disconnect the PCM connector.
2. Disconnect the CPP switch connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

VARIABLE TUMBLE SHUTTER VALVE SWITCH INSPECTION [LF, L3]

Note. Perform the following inspection only when directed.

Scheme 6

Scheme 7

1. Turn the ignition switch to the ON position (Engine off).
2. Verify that the PCM terminal 2AE voltage is as shown in the following table when the variable tumble shutter valve actuator rod is depressed and released by hand. If not as specified, perform the "Circuit Open/Short Inspection". If there is no open or short circuit, replace the intake manifold. Variable tumble shutter valve switch output voltage VOLTAGE SPECIFICATION Condition PCM terminal 2AE Released (Open position) Approx. 5.0 V Depressed (Closed position) Less than 0.4 V

Scheme 8

Scheme 9

1. Disconnect the PCM connector.
2. Inspect the following harness for an open or short wiring. (Continuity inspection)

Resistance Inspection

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

1. Disconnect the ECT sensor connector.
2. Remove the ECT sensor. (See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [LF, L3]» ).
3. Place the ECT sensor in the water and while increasing the water temperature, measure the resistance between ECT sensor terminals A and B. If the monitor item status/specification (reference) is not within the specification, even though the ECT sensor resistance is within the specification, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". If not within the specification, replace the ECT sensor. Standard WATER TEMPERATURE AND RESISTANCE SPECIFICATION Water temperature (°C {°F}) Resistance (kilohm) 20 {68} 35.48-39.20 70(158} 5.07-5.60 80(176} 3.65-4.02

Scheme 10

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

MASS AIR FLOW (MAF) SENSOR INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

Visual Inspection

1. Visually inspect the MAF sensor for the following: Damage, cracks Rusted sensor terminal Bent sensor terminal If there is any malfunction, replace the MAF sensor. If the monitor item status/specification (reference) is not within the specification even though there is no malfunction, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ".

Voltage Inspection

1. Remove the MAF/IAT sensor without disconnect the MAF/IAT sensor connector.
2. Turn the ignition switch to the ON position.
3. As the air gradually approaches the MAF detection part of the MAF/IAT sensor, verify that the voltage at PCM terminal 1AK(California emission regulation applicable model and except for California emission regulation applicable model with LF MTX, L3), 1AC(Except for California emission regulation applicable model with LF ATX) (M-MDS PID: MAF) varies. If it cannot be verified even though the related harnesses have no malfunction, replace the MAF/IAT sensor. (See «INTAKE AIR SYSTEM REMOVAL/INSTALLATION [LF, L3]», «INTAKE AIR SYSTEM REMOVAL/INSTALLATION [LF, L3]».)

Scheme 11

Scheme 12

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF, L3]» ).
2. Disconnect the MAF sensor connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

INTAKE AIR TEMPERATURE (IAT) SENSOR INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

Scheme 13

1. Disconnect the mass air flow sensor connector.
2. Verify that the resistance between MAF sensor terminals D and E is within the specification. If the monitor item status/specification (reference) is not within the specification, even though the IAT sensor resistance is within the specification, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". If not within the specification, replace the MAF sensor. Standard AMBIENT TEMPERATURE AND RESISTANCE SPECIFICATION Ambient temperature (°C{°F}) Resistance (kilohm) -20 {-4.0} 13.6-18.4 20 {68} 2.21-2.69 60 {140} 0.493-0.667

Circuit Open/Short Inspection

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

1. Remove the MAP sensor with the connector still connected. (See «MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR REMOVAL/INSTALLATION [LF, L3]» ).
2. Remove the vacuum hose of the MAP sensor.
3. Verify that the voltage at PCM terminal 2AL is within the specification when the ignition switch is turned to the ON position. If not within the specification, replace the MAP sensor. Voltage 2.69-4.37 V
4. Install the vacuum pump.
5. Turn the ignition switch to the ON position.
6. Verify that change in voltage is within the specification when a vacuum of 30 kPa {225 mmHg, 8.86 inHg} is applied using a vacuum pump. If not within the specification, replace the MAP sensor. Voltage variance 1.16-1.27V

Scheme 14

1. Disconnect the PCM connector.
2. Inspect the following wiring harness for an open or short circuit. (Continuity inspection)

THROTTLE POSITION (TP) SENSOR INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See «FOREWORD [LF, L3]».)

Scheme 15

Scheme 16

1. Verify that no DTC related to APP sensor has been detected. If any DTCs related to APP sensor have been detected, perform the DTC inspection. (See «DTC TABLE [LF, L3]»(/mazda/3/bl-2008-2011/remont/testing-diagnostics/#on-board-diagnostic-engine-controls-lf-l3) .)
2. Connect the M-MDS to the DLC-2.
3. Turn the ignition switch to ON position.
4. Select TP1 or TP2 PID (percentage) on the M-MDS.
5. Verify that the TP1 or TP2 PID is within the specification when the accelerator pedal not depressed. (See «PCM INSPECTION [LF, L3]» ).
6. Operate the accelerator pedal and verify that the TP1 or TP2 PID (percentage) changes as shown in the following graph. If not verified, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". If there is no open or short circuit, replace the throttle body. (See «INTAKE AIR SYSTEM REMOVAL/INSTALLATION [LF, L3]», «INTAKE AIR SYSTEM REMOVAL/INSTALLATION [LF, L3]».)

Scheme 17

1. Disconnect the PCM connector.
2. Disconnect the throttle body connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the troubleshooting flowchart. (See «FOREWORD [LF, L3]».)

1. Connect the M-MDS to the DLC-2.
2. Turn the ignition switch to ON position.
3. Select APP1 and APP2 PID on the M-MDS.
4. Verify that the APP1 and APP2 PID is within the specification when the accelerator pedal not depressed. (See «PCM INSPECTION [LF, L3]» ).

Scheme 18

1. Disconnect the PCM connectors.
2. Disconnect the APP sensor connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

Scheme 19

1. If there is no continuity in the following wiring harnesses, there is an open circuit. Repair or replace the wiring harness. APP sensor terminal A and PCM terminal 1AL(California emission regulation applicable model)(Except for California emission regulation applicable model with LF MTX, L3), 1AW(Except for California emission regulation applicable model with LF ATX) APP sensor terminal B and PCM terminal 1AP (California emission regulation applicable model) (Except for California emission regulation applicable model with LF MTX, L3) 1Y(Except for California emission regulation applicable model with LF ATX) APP sensor terminal C and PCM terminal 1AS(California emission regulation applicable model), 1AV(Except for California emission regulation applicable model with LF MTX, L3),1AA(Except for California emission regulation applicable model with LF ATX) APP sensor terminal D and PCM terminal body ground APP sensor terminal E and PCM terminal 1AC(California emission regulation applicable model), 1AO(Except for California emission regulation applicable model with LF MTX, L3), 1AL(Except for California emission regulation applicable model with LF ATX) APP sensor terminal F and main relay terminal A

AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) INSPECTION [LF, L3]

Front/rear HO2S heater resistance inspection

1. Disconnect the Front/rear HO2S connector.
2. Measure the Front/rear HO2S resistance between terminals C and D. If not within the specification, replace the Front/rear HO2S. Middle/rear HO2S heater resistance 2-50 ohms

Front/rear HO2S circuit open/short inspection (heater)

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

A/F sensor current inspection

1. Warm up the engine to normal operating temperature.
2. Using the M-MDS, monitor the following: Vehicle speed (PID: VSS) Engine speed (PID: RPM) A/F sensor current (PID: 02S11)
3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
4. Verify that the A/F sensor current (PID: O2S11) is 0.25 mA or more while decelerating as shown in the figure. If not within the specification, inspect the A/F sensor for an open or short circuit. (See «A/F SENSOR CIRCUIT OPEN/SHORT INSPECTION (SENSOR)» ). Then if there is no malfunction in the wiring harness, replace the A/F sensor.

Scheme 20

1. Disconnect the A/F sensor connector.
2. Measure the resistance between A/F sensor terminals C and D. If not within the specification, replace the A/F sensor. (See «AIR FUEL RATIO (A/F) SENSOR, HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF, L3]» ). A/F sensor heater resistance 1-10 ohms [20°C {68°F}]

Scheme 21

1. Disconnect the PCM connector.
2. Disconnect the A/F sensor connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

HO2S voltage inspection

1. Warm up the engine to normal operating temperature.
2. Using the M-MDS, monitor the following: Vehicle speed (PID: VSS) Engine speed (PID: RPM) HO2S voltage (PID: O2S12)
3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
4. Verify that the HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the HO2S voltage (PID: O2S12) is 0.3 V or less while decelerating as shown in the figure. If not within the specification, inspect the HO2S for an open or short circuit. (See «HO2S CIRCUIT OPEN/SHORT INSPECTION (SENSOR)» ). Then if there is no malfunction in the wiring harness, replace the HO2S.

Scheme 22

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

HO2S circuit open/short inspection (heater)

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [LF, L3]

Note. Perform the following inspection according to the DATA MONITOR function (indicated by monitor item from here onwards).

Air Gap Inspection

1. Verify that the CKP sensor is securely installed.
2. Using a thickness gauge, measure the air gap between the plate projections at the back of crankshaft pulley and the CKP sensor. If not within the specification, inspect the plate projections for cracks or bending. If there is any malfunction, replace the plate. If the monitor item condition/specification (reference) is not within the specification, even though there is no malfunction, carry out the "Circuit Open/Short Inspection". Air gap 0.5-1.5 mm {0.02-0.05 in}

1. Disconnect the negative battery cable.
2. Remove the CKP sensor. (See «CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [LF, L3]» ).
3. Verify that there are no metal shavings on the sensor. If the monitor item condition/specification (reference) is without the specification even though there is no malfunction, carry out the "Circuit Open/Short Inspection".

Scheme 23

1. Idle the engine. CAUTION: Water penetrating the connector will cause sensor malfunction. To prevent this, be careful not to damage the wiring harnesses or the waterproof connector so as to cause water penetration.
2. Measure the output voltage using a oscilloscope. If not within the specification, replace the CKP sensor. If the monitor item condition/specification (reference) is without the specification, even though the voltage is within the specification, carry out the "Circuit Open/Short Inspection". Voltage VOLTAGE SPECIFICATION Terminal Voltage (V) Condition A 0 Under any condition B 4.8 or more High output (1) 0.8 or less Low output (1) C B+ Under any condition (1) Output voltage varies with crankshaft rotation.

Scheme 24

1. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

CAMSHAFT POSITION (CMP) SENSOR INSPECTION [LF, L3]

Note. Perform the following inspection according to the DATA MONITOR function (indicated by monitor item from here onwards).

1. Disconnect the negative battery cable.
2. Remove the CMP sensor. (See «CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [LF, L3]» ).
3. Verify that there are no metal shavings on the sensor. If the monitor item condition/specification (reference) is not within the specification even though there is no malfunction, carry out the "Circuit Open/Short Inspection".

Scheme 25

1. Idle the engine. CAUTION: Water penetrating the connector will cause sensor malfunction. To prevent this, be careful not to damage the wiring harnesses or the waterproof connector so as to cause water penetration.
2. Measure the output voltage using a oscilloscope. If not within the specification, replace the CMP sensor. If the monitor item condition/specification (reference) is not within the specification, even though the voltage is within the specification, carry out the "Circuit Open/Short Inspection". Voltage VOLTAGE SPECIFICATION Terminal Voltage (V) Condition A 0 Under any condition B 4.8 or more High output (1) 0.8 or less Low output (1) C B+ Under any condition (1) Output voltage varies with camshaft rotation.

1. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

KNOCK SENSOR (KS) INSPECTION [LF, L3]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart.

1. Disconnect the knock sensor connector.
2. Measure resistance between KS terminals A and B. If not within the specification, replace the KS. If the monitor item status/specification (reference) is not within the specification, even though the KS resistance is within the specification, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". Resistance Approx. 4.87 megohms

Scheme 26

1. Disconnect the PCM connector.
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

BAROMETRIC PRESSURE (BARO) SENSOR INSPECTION [LF, L3]

Note. Perform the following inspection only when directed. The following vacuum values are indicated by relative pressure from the PCM. (See «PCM REMOVAL/INSTALLATION [LF, L3]» ).

1. Connect the M-MDS to the DLC-2.
2. Turn the ignition switch to the ON position.
3. Select BARO on the M-MDS.
4. Verify that the BARO PID (pressure) and barometric pressure are practically equal. If not as verified, perform the " «CIRCUIT OPEN/SHORT INSPECTION» ". If there is no open or short circuit, replace the PCM.

See also:
• DTC TABLE [LF, L3]