Engine Control System: Diagnosis Mazda MX-5 NC

NEUTRAL SWITCH INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 26

1. Remove the neutral switch. (See «NEUTRAL SWITCH REMOVAL/INSTALLATION [M15M-D]»(ref-244481-S14225015202006092400000).) (See «NEUTRAL SWITCH REMOVAL/INSTALLATION [P66M-D]»(ref-244462-S25848329282006092400000).)
2. Verify that the continuity between neutral switch terminals 1A and 2A is as indicated in (Scheme 28). If not as indicated in (Scheme 28), replace the neutral switch. (See «NEUTRAL SWITCH REMOVAL/INSTALLATION [M15M-D]»(ref-244481-S14225015202006092400000).) (See «NEUTRAL SWITCH REMOVAL/INSTALLATION [P66M-D]»(ref-244462-S25848329282006092400000).) If the monitor item condition/specification (reference) is not within the specification, even though there is no malfunction, perform the «CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S05179007452006092400000).

Scheme 27

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harness for open or short circuit (continuity Inspection).

CLUTCH PEDAL POSITION (CPP) SWITCH INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 28

1. Remove the CPP switch. (See «CLUTCH PEDAL REMOVAL/INSTALLATION»(ref-244470-S17358566232006092400000).)
2. Verify that the continuity between CPP switch terminals D and B is as indicated in (Scheme 30). If not as indicated in (Scheme 30), replace the CPP switch. (See «CLUTCH PEDAL REMOVAL/INSTALLATION»(ref-244470-S17358566232006092400000).) If the monitor item condition/specification (reference) is not within the specification, even though there is no malfunction, perform the «CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S15468069092006092400000).

Scheme 29

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harness for open or short circuit (continuity Inspection).

POWER STEERING PRESSURE (PSP) SWITCH INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 30

1. Inspect the following items: Power steering fluid amount (See «POWER STEERING FLUID INSPECTION»(ref-244476-S15635912252006092400000).) Power steering-related inspection (See «STEERING LOCATION INDEX»(ref-244476-S03639347162006092400000).)
2. Disconnect the PSP switch connector.
3. Start the engine.
4. Verify that the continuity between PSP switch terminal A and body ground is as indicated in see scheme 26. If not as indicated in see scheme 26, replace the CPP switch. (See «POWER STEERING OIL PUMP DISASSEMBLY/ASSEMBLY»(ref-244476-S25868125072006092400000).) If the monitor item condition/specification (reference) is not within the specification, even though there is no malfunction, perform the «CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S25425093132006092400000).

Scheme 31

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harness for open or short circuit (continuity Inspection).

ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Resistance Inspection

1. Remove the battery cover.
2. Disconnect the negative battery cable. (See «BATTERY REMOVAL/INSTALLATION [LF]»(ref-244448-S25513985422006092400000) .)
3. Disconnect the ECT sensor connector.
4. Remove the ECT sensor. (See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S25963678032006092400000) .)
5. 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»(ref-244452-S08161792242006092400000) . If not within the specification, replace the ECT sensor. (See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S25963678032006092400000) )

STANDARD ECT SENSOR RESISTANCE SPECIFICATION

Scheme 32

Scheme 33

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

INTAKE AIR TEMPERATURE (IAT) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 34

1. Remove the battery cover.
2. Disconnect the negative battery cable. (See «BATTERY REMOVAL/INSTALLATION [LF]»(ref-244448-S25513985422006092400000) .)
3. Disconnect the MAF/IAT sensor connector.
4. Verify that the resistance between MAF/IAT 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»(ref-244452-S19997998012006092400000) . If not within the specification, replace the MAF/IAT sensor. (See «MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION»(ref-244452-S31229317942006092400000)

STANDARD MAF/IAT SENSOR RESISTANCE SPECIFICATION

Scheme 35

Scheme 36

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

CRANKSHAFT POSITION (CKP) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 37

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 crankshaft pulley. (See «ENGINE REMOVAL/INSTALLATION [LF]»(ref-244453-S22263767602006092400000) .) 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»(ref-244452-S20887751752006092400000) . Air gap 0.5-1.5 mm {0.02-0.05 in}

Visual Inspection

1. Remove the battery cover.
2. Disconnect the negative battery cable. (See «BATTERY REMOVAL/INSTALLATION [LF]»(ref-244448-S25513985422006092400000) .)
3. Remove the CKP sensor. (See «CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S28144161072006092400000) .)
4. 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»(ref-244452-S20887751752006092400000) .

Scheme 38

1. Install all removed parts.
2. 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.
3. Measure the output voltage using an oscilloscope. If not within the specification, replace the CKP sensor. (See «CRANKSHAFT POSITION (CKP) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S28144161072006092400000) .) 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»(ref-244452-S20887751752006092400000) .

CKP SENSOR VOLTAGE SPECIFICATION

Circuit Open/Short Inspection

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity Inspection)

Scheme 39

Scheme 40

CAMSHAFT POSITION (CMP) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

1. Remove the battery cover.
2. Disconnect the negative battery cable. (See «BATTERY REMOVAL/INSTALLATION [LF]»(ref-244448-S25513985422006092400000) .)
3. Remove the CMP sensor. (See «CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S33999344992006092400000) .)
4. 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»(ref-244452-S27130360512006092400000) .

Scheme 41

1. Install all removed parts.
2. 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.
3. Measure the output voltage using an oscilloscope. If not within the specification, replace the CMP sensor. (See «CAMSHAFT POSITION (CMP) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S33999344992006092400000) .) 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»(ref-244452-S27130360512006092400000) .

CMP SENSOR TERMINALS VOLTAGE SPECIFICATION

Scheme 42

Scheme 43

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity Inspection)

THROTTLE POSITION (TP) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 44

Scheme 45

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]»(ref-244449-S40344338372006092400000).)
2. Connect the WDS or equivalent to the DLC-2.
3. Turn the ignition switch to the ON position.
4. Select TP1 or TP2 PID (percentage) on the WDS or equivalent.
5. Verify that the TP1 or TP2 PID is within the specification when the accelerator pedal not depressed. (See «PCM INSPECTION [LF]»(ref-244452-S30974371722006092400000).)
6. Operate the accelerator pedal and verify that the TP1 or TP2 PID (percentage) changes see scheme 49 If not verified, perform the «CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S33973259452006092400000). If there is no open or short circuit, replace the throttle body. (See «INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [LF]»(ref-244455-S24513161252006092400000).)

Scheme 46

Scheme 47

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
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]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

1. Connect the WDS or equivalent to the DLC-2.
2. Turn the ignition switch to the ON position.
3. Select APP1 and APP2 PID on the WDS or equivalent.
4. Verify that the APP1 and APP2 PID is within the specification when the accelerator pedal not depressed. (See «PCM INSPECTION [LF]»(ref-244452-S30974371722006092400000) .)

Scheme 48

Scheme 49

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Disconnect the APP sensor connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

MASS AIR FLOW (MAF) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

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/IAT sensor. (See «MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S31229317942006092400000) .)

Voltage Inspection

1. Remove the MAF/IAT sensor without disconnecting 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 MAF sensor output voltage (WDS PID: MAF) varies. If it cannot be verified even though the related wiring harnesses have no malfunction, replace the MAF/IAT sensor. (See «MASS AIR FLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S31229317942006092400000) .)

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harness for open or short circuit (continuity Inspection).

FRONT HEATED OXYGEN SENSOR (HO2S) INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 50

1. Warm up the engine to normal operating temperature.
2. Using the WDS or equivalent, monitor the following: Vehicle speed (PID: VSS) Engine speed (PID: RPM) Front HO2S current (PID: O2S11)
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 front HO2S current (PID: O2S11) is 0.25 mA or more while decelerating (Scheme 54) If not within the specification, inspect the front HO2S for an open or short circuit. (See «FRONT HO2S CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S37695124502006092400000).) Then if there is no malfunction in the wiring harness, replace the front HO2S. (See «FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF]»(ref-244452-S41964357682006092400000).)

Scheme 51

1. Disconnect the front HO2S connector.
2. Measure the resistance between front HO2S terminals C and D. If not within the specification, replace the front HO2S. (See «FRONT HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF]»(ref-244452-S41964357682006092400000) .) Front HO2S heater resistance 1-10 ohms

Scheme 52

Scheme 53

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Disconnect the front HO2S connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)

REAR HEATED OXYGEN SENSOR (HO2S) INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

Scheme 54

1. Warm up the engine to normal operating temperature.
2. Using the WDS or equivalent, monitor the following: Vehicle speed (PID: VSS) Engine speed (PID: RPM) Rear 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 rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the rear HO2S voltage (PID: O2S12) is 0.3 V or less while decelerating (Scheme 59) If not within the specification, inspect the rear HO2S for an open or short circuit. (See «REAR HO2S CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S28378324392006092400000).) Then if there is no malfunction in the wiring harness, replace the rear HO2S. (See «REAR HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF]»(ref-244452-S06130148932006092400000).)

Scheme 55

1. Disconnect the rear HO2S connector.
2. Measure the rear HO2S resistance between terminals C and D. If not within the specification, replace the rear HO2S. (See «REAR HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF]»(ref-244452-S06130148932006092400000) .) Rear HO2S heater resistance 2-50 ohms

Scheme 56

Scheme 57

1. Disconnect the PCM connector.
2. Disconnect the rear HO2S connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity Inspection)

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

1. Connect the WDS or equivalent to the DLC-2.
2. Turn the ignition switch to the ON position (Engine off).
3. Select MAP PID on the WDS or equivalent.
4. Verify that the MAP PID (pressure) and barometric pressure are practically equal. If not as verified, perform the «CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S22013088592006092400000) . If there is no open or short circuit, replace the MAP sensor. (See «MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S31739968622006092400000) .) If as verified, go to next step.
5. Apply vacuum of -25.0 kPa {-187 mmHg, -7.38 inHg} to the MAP sensor, and verify that the MAP variation from that of Step 4 is approx. 25.0 kPa {187 mmHg, 7.38 inHg}. If not as verified, perform the «CIRCUIT OPEN/SHORT INSPECTION»(ref-244452-S22013088592006092400000) . If there is no open or short circuit, replace the MAP sensor. (See «MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR REMOVAL/INSTALLATION [LF]»(ref-244452-S31739968622006092400000) .)

Scheme 58

Scheme 59

1. Disconnect the PCM connector. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)
2. Inspect the following wiring harnesses for an open or short circuit. (Continuity Inspection)

KNOCK SENSOR (KS) INSPECTION [LF]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

1. Remove the battery cover.
2. Remove the negative battery cable. (See «BATTERY REMOVAL/INSTALLATION [LF]»(ref-244448-S25513985422006092400000) .)
3. Disconnect the KS connector.
4. Measure resistance between KS terminals A and B. If not within the specification, replace the KS. (See «KNOCK SENSOR (KS) REMOVAL/INSTALLATION [LF]»(ref-244452-S26956623482006092400000) .) 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»(ref-244452-S40001663522006092400000) . KS resistance Approx. 4.87 megohms

Scheme 60

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]

Note. Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flow diagram. (See TROUBLESHOOTING PROCEDURE .)

1. Connect the WDS or equivalent to the DLC-2.
2. Turn the ignition switch to the ON position.
3. Select BARO PID on the WDS or equivalent.
4. Verify that the BARO PID (pressure) and barometric pressure are practically equal. If not as verified, replace the PCM. (See «PCM REMOVAL/INSTALLATION [LF]»(ref-244452-S11022070362006092400000) .)