Engine Controls - System & Component Testing: Other Mazda MPV II

Lysholm Compressor

Remove drive belt. Rotate compressor shaft by hand. Compressor shaft should rotate smoothly. Check for cracks or damage. Replace compressor as necessary.

Air By-Pass Valve (ABV) Actuator

Remove ABV actuator. (Scheme 26) Verify air does not flow from port "A" to port "B". (Scheme 27) Connect a vacuum pump to ABV actuator port "C" and apply over 10 in. Hg of vacuum. Air should flow from port "A" to port "B". Airflow should increase as vacuum to port "C" is increased. If ABV actuator does not operate as specified, replace ABV actuator.

Scheme 26

Scheme 27

Charge Air Cooler (Intercooler)

Remove charge air cooler and inspect for cracks, restriction or damage. Replace as necessary.

Charge Air Cooler By-Pass (System Check)

1. Connect scan tool to DLC-2. Start engine and verify charge air cooler by-pass actuator rod is retracted. (Scheme 26)
2. Select SIMULATION TEST function. Select CACBYP. Using SIMULATION TEST function, turn off CACBYP and ensure actuator rod returns. If actuator rod operation is not as specified, turn ignition off. Go to next step.
3. Turn ignition on. Using SIMULATION TEST function, ensure operation sound of Charge Air Cooler By-Pass (CACBYP) solenoid valve. If operation sound of CACBYP solenoid valve is not heard, replace CACBYP solenoid valve. If operation sound of CACBYP solenoid valve is heard, check following: Vacuum hose damaged or loose. Vacuum pump. Damaged actuator diaphragm. Sticking shutter valve. Repair as necessary.

Charge Air Cooler (CAC) By-Pass Actuator

Remove vacuum hose from air cooler by-pass actuator. (Scheme 26) Connect vacuum pump to CAC by-pass actuator and apply about 7.5 in. Hg of vacuum. Actuator rod should retract. If CAC by-pass actuator does not operate, replace CAC by-pass actuator.

Charge Air Cooler (CAC) By-Pass Solenoid Valve

Remove CAC by-pass solenoid valve. (Scheme 26) Apply air pressure to solenoid valve port "B". (Scheme 28) Air from port "B" should flow from "C" only. Using fused jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to solenoid valve port "A". Air should flow from port "B" only. If CAC by-pass solenoid valve operation is not as specified, replace CAC by-pass solenoid valve.

Scheme 28

Air By-Pass Valve (ABV) Solenoid Valve (Vacuum)

Remove ABV solenoid valve. (Scheme 26) Apply air pressure to port "A" of ABV solenoid valve. (Scheme 29) Air should not flow from port "B". Using fused jumper wires, apply battery voltage to ABV solenoid valve terminals. Air should flow from port "B". If operation of ABV solenoid valve is not as specified, replace ABV solenoid valve.

Scheme 29

Air By-Pass Valve (ABV) Solenoid Valve (Vent)

1. Remove ABV solenoid valve. (Scheme 26) Apply air pressure to port "A" of ABV solenoid valve. (Scheme 30) Air should flow from ports "B" and "C". Apply air pressure to port "B". Air should flow from port "C". If ABV solenoid valve operates as specified, go to next step. If ABV solenoid valve does not operate as specified, replace ABV solenoid valve.
2. Using fused jumper wires, apply battery voltage to ABV solenoid valve terminals. Apply air pressure to port "A". Air should flow from port "B" only. If ABV solenoid valve does not operate as specified, replace ABV solenoid valve.

Scheme 30

System Check

Start engine, and let idle. IMRC actuator should not operate at engine speeds of less than 3300 RPM. Raise engine speed. IMRC actuator should operate at engine speeds of more than 3300 RPM. Using scan tool, check for DTCs. If DTC P1512, P1518 or P1520 are present, see appropriate test in SELF-DIAGNOSTICS - MPV. If DTCs are not present, start engine. Using scan tool, select SIMULATION TEST. Turn IMRC actuator on and off. If IMRC actuator operation is heard, check IMRC actuator cable tension and condition. Repair as necessary. If IMRC actuator operation is not heard, check Green/White wire between main relay and IMRC actuator terminal No. 2. Check Black/White wire between IMRC actuator terminal No. 3 and ground. Check wire between IMRC actuator terminal No. 1 (Black/Red wire) and PCM terminal No. 42 (Black/Yellow wire). Repair as necessary. If problem is not present, replace IMRC actuator.

VARIABLE INERTIA CHARGING SYSTEM (VICS) - PROTEGE 2.0L

Note. For VICS component locations, see appropriate vacuum diagram in VACUUM DIAGRAMS article.

Note. Shutter valve actuator rod retracts for 5 seconds after engine is started.

Connect scan tool to DLC-2. DLC-2 is located under instrument panel, left of steering column. Select RPM PID. Start engine, and let idle. Turn on all electrical loads. Shutter valve actuator rod should be extended at idle. (Scheme 31) Gradually increase engine speed to 5250 RPM and ensure actuator rod retracts. If system actuator does not operate as specified, check for vacuum leaks. If no vacuum leaks are detected, check shutter valve and shutter valve solenoid.

Scheme 31

Solenoid Valve

Disconnect negative battery cable. Remove solenoid valve. Apply air pressure to port "B". (Scheme 32) Air should flow from "C". Using fused jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to port "B". Air should flow from port "A". Replace solenoid valve as necessary.

Scheme 32

Shutter Valve Actuator

Disconnect vacuum hose from VICS shutter valve actuator. (Scheme 31) Connect vacuum pump to actuator. If rod does not move, disconnect rod and check rod and valve for freedom of movement. Apply vacuum and verify shutter valve rod retracts. Replace as necessary.

Vacuum Chamber

Remove vacuum chamber. Visually inspect vacuum chamber for clogging, cracks and damage. Apply air pressure to port "A" and ensure air flows from port "B". (Scheme 33) Apply air pressure to port "B". Air should flow from port "A". Replace vacuum chamber as necessary.

Scheme 33

VARIABLE INERTIA CHARGING SYSTEM (VICS) - MIATA

Note. For VICS component locations, see appropriate vacuum diagram in VACUUM DIAGRAMS article.

Connect tachometer to engine. Start engine, and let idle. Shutter valve actuator rod should be extended at idle for 5 seconds. After 5 seconds, Shutter valve actuator rod should retract. Gradually increase engine speed to 5250 RPM and ensure actuator rod extends. If system actuator does not operate as specified, check for vacuum leaks. If no vacuum leaks are detected, check for DTC P1523. Diagnose and repair as necessary. If DTC P1523 is not present, use scan tool in SIMULATION TEST mode to actuate solenoid valve. Listen to solenoid while actuating with scan tool. If solenoid clicks, check vacuum actuator, vacuum chamber and vacuum lines. If solenoid does not click, check solenoid. Repair or replace as necessary.

Actuator Check

Disconnect vacuum hose. Using vacuum pump, apply vacuum to actuator. See VICS OPERATION table. If actuator does not operate properly, replace actuator and recheck.

VICS OPERATION

Solenoid Check

Remove solenoid. Check flow between solenoid valve port "B" and "C". (Scheme 28) Flow should be present. Using fused jumper wires, connect battery voltage to solenoid terminal "A" and battery ground to terminal "B". Check flow between solenoid valve port "A" and "B". Flow should be present. If flow is not as specified, replace solenoid.

1. Start engine. Check Variable Resonance Induction System (VRIS) shutter valve actuator rod positions. For 626, see VACUUM DIAGRAMS article. For Millenia (Scheme 34) On all models, VRIS shutter rods should not be pulled. If VRIS shutter valve actuator rods are not pulled, go to step 4. If VRIS shutter valve actuator rods are pulled, go to next step.
2. Turn ignition off. Connect New Generation Star (49 T088 0A0) scan tool to Data Link Connector (DLC) 2. DLC-2 is located under left side of instrument panel, right of steering column. Check for Diagnostic Trouble Codes (DTCs). See appropriate SELF-DIAGNOSTICS - INTRODUCTION article. If any DTCs are present, repair as necessary. If DTCs are not present, go to next step.
3. Start engine and run at idle. Using scan tool, select SIMULATION TEST. Turn both VRIS solenoid valves on using VRISV1 or VRISV2 selection. Listen for clicking noise from VRIS solenoids. If both VRIS solenoids click, check VRIS shutter valve actuators. If VRIS solenoids do not click, check VRIS solenoid valves.
4. Start engine and operate at idle. Check operation of shutter valve actuators No. 1 and 2 at specified engine speed. See «VRIS RPM SPECIFICATIONS (MILLENIA 2.5L & 626 2.5L)»(ref-12154-S35455496102000121300000) table. If actuators do not operate as specified, check for DTCs. See appropriate SELF-DIAGNOSTICS - INTRODUCTION article. Repair as necessary. If no DTCs are present, check VRIS components and Throttle Position (TP) sensor.

VRIS RPM SPECIFICATIONS (MILLENIA 2.5L & 626 2.5L)

Check Valve

Remove check valve. For 626, see VACUUM DIAGRAMS article. For Millenia (Scheme 34) On all models, apply air pressure to port "A" (White port) of check valve. Air should flow from port "B". Apply air pressure to port "B" (Green port) of check valve. Air should not flow from port "A". Replace check valve as necessary.

Shutter Valve Actuators

Disconnect vacuum hose from shutter valve actuators No. 1 and 2. For 626, see VACUUM DIAGRAMS article. For Millenia (Scheme 34) On all models, connect vacuum pump to VRIS shutter valve actuator. Apply vacuum to each VRIS shutter valve actuator separately and ensure VRIS shutter valve rod retracts. If operation is not as specified, remove suspect VRIS shutter valve actuator and ensure actuator moves freely. Replace VRIS shutter valve actuators as necessary.

Remove VRIS solenoid valve. Apply air pressure to port "B". (Scheme 32) Air should flow from "C". Using fused jumper wires, apply battery voltage to VRIS solenoid valve terminals. Apply air pressure to port "A". Air should flow from port "B". Replace VRIS solenoid valve as necessary.

Remove vacuum chamber. Visually inspect vacuum chamber for clogging, cracks and damage. Replace as necessary.

Scheme 34

For system check, see appropriate test in SELF-DIAGNOSTICS - PROTEGE 1.6L or SELF-DIAGNOSTICS 626 article.

One Way Check Valve Check

Remove one way check valve. Blow into valve in direction of arrow on valve. Air should flow. Blow into valve in opposite direction of arrow. Air should not flow. If flow is not as specified, replace one way check valve.

Shutter Valve Actuator Check

Disconnect vacuum hose from actuator. Connect a vacuum pump to actuator. Watch actuator rod and apply vacuum to actuator. See SHUTTER VALVE ACTUATOR CHECK table. If actuator does not operate as specified, replace actuator. If system is not working properly but actuator is okay, check vacuum lines.

SHUTTER VALVE ACTUATOR CHECK

Note. Perform VTCS solenoid check only when directed by SELF-DIAGNOSTICS testing.

VTCS Solenoid Check

Remove solenoid. Check solenoid airflow. (Scheme 35) Apply battery voltage to solenoid. Check airflow. (Scheme 35) If solenoid is okay, check vacuum lines. Repair as necessary. If problem is not present, Check for open or short in wiring. See WIRING DIAGRAMS article. Repair as necessary.

Scheme 35

Ground Circuit Checks

1. Using an ohmmeter, check ground circuits to PCM for continuity to ground. See WIRING DIAGRAMS article to determine PCM ground terminals. See «PCM LOCATIONS»(ref-12154-S07833634812000121300000) table. If continuity is not present, repair open circuit to ground.
2. Using a voltmeter, touch negative lead to a good ground. Touch positive lead to each ground terminal. With vehicle running, voltmeter should indicate less than one volt. If voltage reading is more than one volt, check for open circuit, corrosion, or loose connection on ground lead.

Power Circuit Checks

1. Using a voltmeter, check for battery voltage between PCM constant battery power terminals and ground. See WIRING DIAGRAMS article to determine PCM power terminals. See «PCM LOCATIONS»(ref-12154-S07833634812000121300000) table. If battery voltage is not present, check PCM power supply fuse. If fuse is okay, check for open in power supply or PCM wiring.
2. Turn ignition on. Using a voltmeter, check for battery voltage between PCM ignition power terminals and ground. If battery voltage is not present, check power supply fuse(s). If fuse is okay, check for an open in wiring between fuse and PCM, or check for a defective ignition switch.
3. Connect voltmeter between ground and PCM start (crank) signal terminal. Turn ignition switch to START position. Battery voltage should be present between PCM start terminal and ground only when ignition switch is in START position. If voltage is not present, check fuse(s). If fuse is okay, check for open circuit in wiring harness between fuse and PCM. If wiring harness is okay, check for a defective ignition switch.

PCM LOCATIONS

BRAKELIGHT SWITCH

Disconnect brakelight switch connector. Using ohmmeter, check continuity between brakelight switch terminals. With brake pedal released, continuity should not be present. With brake pedal depressed, continuity should be present. If continuity is not as specified, replace brakelight switch.

Miata

1. Remove and inspect camshaft position sensor. Clean off any metal particles or shavings. Reinstall sensor.
2. Connect scan tool. Start engine. Using scan tool, enter vehicle info and connect scan tool leads to PCM. See «CMP/PCM TERMINAL IDENTIFICATION (MIATA & PROTEGE 1.6L)»(ref-12154-S31416355792000121300000) table. Select DIGITAL MEASUREMENT SYSTEM, then FREQUENCY METER. Press link key to select RPM PID. Select PID/DATA MONITOR, then PCM. Press START.
3. Frequency meter should be displayed. Ensure threshold voltage is 2 volts and DC voltage is selected. Frequency should match specifications. See «CMP FREQUENCY SPECIFICATIONS (MIATA & PROTEGE 1.6L)»(ref-12154-S18226251872000121300000) table.
4. Change scan tool threshold voltage to 6 volts. Ensure frequency is 0 Hz. If frequency is out of specifications, check wiring for open or short circuit. Check camshaft pulley for damage. Repair as necessary.

CMP/PCM TERMINAL IDENTIFICATION (MIATA & PROTEGE 1.6L)

CMP FREQUENCY SPECIFICATIONS (MIATA & PROTEGE 1.6L)

Millenia 2.3L

CMP sensor is located on right front of engine. Disconnect negative battery cable. Disconnect CMP sensor connector. Using ohm meter, check continuity between CMP connector terminals "B" and "C". If continuity is present, replace CMP sensor. If continuity is not present, repair wire harness as necessary.

Millenia 2.5L

CMP sensor is located inside of distributor and is an integrated part. Disconnect distributor 6-pin harness connector. Using ohm meter, check continuity between distributor connector terminals "B" and "D". If continuity is present, replace distributor. If continuity is not present, repair wire harness as necessary.

MPV

Disconnect CMP sensor connector. Check resistance between sensor terminals. If resistance is not 292-385 ohms, replace sensor. If resistance is 292-385 ohms, disconnect PCM harness connector. Connect breakout box to PCM harness connector. Leave PCM disconnected. Check continuity of wire between CMP sensor harness connector terminal "A" (Blue wire) and breakout box terminal No. 85. Check continuity wire between CMP sensor harness connector terminal "B" (Yellow wire) and breakout box terminal No. 86.

Protege 1.6L

1. Remove and inspect camshaft position sensor. Clean off any metal particles or shavings. Reinstall sensor.
2. Remove PCM. Connect 104-pin breakout box between PCM and PCM harness connector. Connect scan to DLC-2. DLC-2 is located under left side of instrument panel. Connect test leads to breakout box. See «CMP/PCM TERMINAL IDENTIFICATION (MIATA & PROTEGE 1.6L)»(ref-12154-S31416355792000121300000) table.
3. Start engine. Monitor RPM PID. Frequency meter should be displayed. Ensure threshold voltage is 2 volts and DC voltage is selected. Frequency should match specifications. See «CMP FREQUENCY SPECIFICATIONS (MIATA & PROTEGE 1.6L)»(ref-12154-S18226251872000121300000) table.
4. Change scan tool threshold voltage to 6 volts. Ensure frequency is 0 Hz. If frequency or breakout box terminal No. 85 voltage is out of specifications, check wiring for open or short in Blue wire between CMP sensor harness connector terminal "B" and PCM harness connector terminal No. 85. Repair as necessary.

Protege 2.0L

Disconnect CMP sensor harness connector. CMP sensor is located in timing belt cover, in upper front of engine. Using ohmmeter, measure resistance between component terminals. Resistance should be 950-1250 ohms. Replace as needed. If sensor is okay, check for open or short circuit in Blue wire between CMP sensor 2-pin harness connector and PCM harness connector terminal No. 85. Repair as necessary.

626 2.0L

Disconnect CMP sensor harness connector. CMP sensor is located in timing belt cover, in upper front of engine. Using ohmmeter, measure resistance between component terminals. Resistance should be 950-1250 ohms. Replace as needed.

626 2.5L

Disconnect CMP sensor harness connector. CMP sensor is located next to right timing pulley. Using ohmmeter, measure resistance between component terminals. Resistance should be approximately 550 ohms. Replace as needed.

Millenia

Closed throttle position switch is part of Throttle Position (TP) sensor. To test closed throttle position switch, check TP sensor continuity. See THROTTLE POSITION SENSOR (TP) in ON-VEHICLE ADJUSTMENTS article. Check TP sensor adjustment before replacing TP sensor.

Miata, Protege & 626

Disconnect clutch switch connector. Using ohmmeter, check continuity between switch terminals. With clutch pedal depressed, continuity should be present. With clutch pedal released, continuity should not be present. If continuity is not as specified, replace clutch switch.

CRANKSHAFT POSITION (CKP) SENSOR

1. CKP sensor is located on front of engine, near crankshaft pulley. Disconnect CKP sensor connector. Using ohmmeter, measure resistance between terminals "A" and "B" at CKP sensor. (Scheme 36) Resistance should be as specified. See «CRANKSHAFT POSITION SENSOR RESISTANCE SPECIFICATIONS»(ref-12154-S10014843482000121300000) table.
2. If resistance is not as specified, replace CKP sensor. If resistance is as specified, measure CKP sensor air gap. Air gap should be.020-.060" (.5-1.5 mm). On Miata and Protege 1.6L, when testing or replacing CKP sensor, set air gap to.020-.060" (.5-1.5 mm). On all models, if air gap is not as specified, replace CKP sensor or crankshaft pulley. MPV has no air gap specification.

CRANKSHAFT POSITION SENSOR RESISTANCE SPECIFICATIONS

Scheme 36

EGR BOOST SENSOR

See EXHAUST GAS RECIRCULATION (EGR) SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS.

Except Miata

Remove ECT sensor. Place ECT sensor and thermometer in a container of water. Connect ohmmeter between ECT sensor terminals. Slowly heat water. Observe resistance reading at specified temperatures. See ENGINE COOLANT TEMPERATURE (ECT) SENSOR SPECIFICATIONS table. If resistance is not as specified, replace ECT sensor.

1. Coolant temperature sender is part of ECT sensor. Remove ECT sensor. ECT sensor is located on left side of engine. Place ECT sensor and thermometer in a container of water. Connect ohmmeter between ECT sensor terminals "A" and "B". (Scheme 37)
2. Slowly heat water. Observe resistance reading at specified temperatures. See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR SPECIFICATIONS»(ref-12154-S38579030732000121300000) table. If resistance is not as specified, replace ECT sensor.
3. To check coolant temperature sender portion of ECT sensor, measure resistance between ground and ECT sensor terminal "C". (Scheme 37) Resistance should be 160-230 ohms with sensor temperature at 122°F (50°C). Replace ECT sensor as necessary.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR SPECIFICATIONS

Scheme 37

FUEL TANK PRESSURE (FTP) SENSOR

1. Connect NGS scan tool to DLC-2. DLC-2 is located under left side of instrument panel, right of steering column. Turn ignition on. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD. Select FTP V PID.
2. With 2 psi (6.6 kPa) of pressure applied to sensor, voltage should be 4-5 volts. With 0 psi (0 kPa) of pressure applied to FTP sensor, voltage should be 2.3-2.8 volts. With 2 in. Hg of vacuum applied to sensor, voltage should be 4.5-5.0 volt. If all voltage readings are as specified, FTP sensor is functioning properly. If any voltage reading is not as specified, go to next step.
3. Turn ignition off. Check continuity of circuits between FTP sensor wiring harness connector and PCM. See WIRING DIAGRAMS article. If continuity is present in all circuits, go to next step. If continuity is not present in one or more circuits, repair wiring harness as necessary.
4. Turn ignition on. Measure voltage at terminal "B" at FTP sensor wiring harness connector. (Scheme 38) Voltage should be less than one volt. Measure voltage at terminal "C" at FTP sensor wiring harness connector. Voltage should be 4.5-5.5 volts. If voltage is as specified, replace FTP sensor. If voltage is not as specified, locate and repair short circuit in wiring harness. See WIRING DIAGRAMS article.

Scheme 38

1. Warm engine to normal operating temperature. Connect NGS scan tool to DLC-2. DLC-2 is located under left side of instrument panel, behind fuse block cover. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD.
2. Turn ignition on. Select FHO2S PID for front sensor or RHO2S PID for rear sensor. See «HO2S VOLTAGE (MIATA)»(ref-12154-S30827004402000121300000) table. If voltage is not as specified, check wiring harness between PCM and HO2S. Also check intake manifold system, fuel system and self-diagnostic system. Repair as necessary. If problems are not present, replace HO2S.
3. To test HO2S heating element, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between sensor terminals "C" and "D". (Scheme 39) Resistance should be about 16 ohms with sensor temperature at 68°F (20°C). If resistance is not as specified, replace HO2S.

HO2S VOLTAGE (MIATA)

Scheme 39

1. Warm engine to normal operating temperature. Connect scan tool to DLC-2. DLC-2 is located under left side of instrument panel, right of steering column. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD.
2. Turn ignition on. Select appropriate HO2S PID to be checked. Voltage should be.5-1.0 volt under acceleration and 0-.5 volt under deceleration. If voltage is not as specified, check wiring harness and connector between PCM and HO2S. Also check intake air system, fuel system and self-diagnostic system. Repair as necessary. If problems are not present, replace suspect HO2S.
3. To test HO2S heating element on 2.5L, go to next step. To test HO2S heating element on 2.3L, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between sensor terminals "B" and "C" for front HO2S 3-pin connector or terminals "C" and "D" for rear HO2S 4-pin connector. (Scheme 40) Resistance should be about 6 ohms with sensor temperature at 68°F (20°C). If resistance is not as specified, replace HO2S.
4. To test HO2S heating element on 2.5L, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between HO2S 4-pin connector terminals "C" and "D". (Scheme 41) Rear HO2S resistance should be 6 ohms with sensor temperature at 68°F (20°C). Front HO2S resistance should be 3.3 ohms with sensor temperature at 68°F (20°C). If resistance is not as specified, replace HO2S.

Scheme 40

Scheme 41

1. Warm engine to normal operating temperature. Turn ignition off. Disconnect suspect HO2S connector. Connect voltmeter to sensor terminals. See «HO2S TERMINAL IDENTIFICATION (MPV)»(ref-12154-S21663411062000121300000) table. Start engine. Raise engine speed to 3000 RPM until voltage varies between zero and one volt. Allow engine to idle. Accelerate engine several times. Voltage should be .5-1.0 volt when accelerating, 0-.5 volt when decelerating. If voltage is as specified, go to next step. If voltage is not as specified, replace HO2S.
2. Check for open or short in wiring between suspect HO2S and PCM. See WIRING DIAGRAMS article. Repair as necessary.
3. To test HO2S heating element, allow sensor to cool to room temperature. Disconnect HO2S connector. Using ohmmeter, measure resistance between specified terminals. See HO2S HEATER TERMINAL RESISTANCE SPECIFICATION (MPV) table. If resistance is not as specified, replace HO2S.

HO2S TERMINAL IDENTIFICATION (MPV)

HO2S HEATER TERMINAL RESISTANCE SPECIFICATION (MPV)

Protege

1. Warm engine to normal operating temperature. Connect NGS scan tool to DLC-2. DLC-2 is located under left side of instrument panel, left of steering column. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD.
2. Turn ignition on. Select FHO2S PID for front sensor or RHO2S PID for rear sensor. See «HO2S VOLTAGE (PROTEGE)»(ref-12154-S32142254802000121300000) table. If voltage is not as specified, check wiring harness between PCM and HO2S. Also check intake manifold system, fuel system and self-diagnostic system. Repair as necessary. If problems are not present, replace HO2S.
3. To test HO2S heating element, allow sensor to cool to room temperature. Disconnect front HO2S connector. Measure resistance between front HO2S terminals "C" and "D". (Scheme 42) Resistance should be about 6 ohms at 68°F (20°C). If resistance is not as specified, replace front HO2S.
4. Disconnect rear HO2S connector. Measure resistance between rear HO2S terminals "C" and "D". (Scheme 42) Resistance should be about 16 ohms. If resistance is not as specified, replace rear HO2S.

HO2S VOLTAGE (PROTEGE)

Scheme 42

626 2.0L (Using Breakout Box)

1. Warm engine to normal operating temperature. Turn ignition off. Connect 104-Pin Breakout Box (49 UN01 130) to PCM. Measure voltage at PCM terminal No. 60 for front HO2S or No. 35 for rear HO2S. See «HO2S VOLTAGE (626 2.0L)»(ref-12154-S24293212852000121300000) table.
2. If voltage is not as specified, check wiring harness and connector between PCM and HO2S. Also check intake manifold system, fuel system and self-diagnostic system. Repair as necessary. If no problems are present, replace HO2S.
3. To test HO2S heating element, allow HO2S to cool to room temperature. Disconnect HO2S 4-pin connector. Using ohmmeter, measure resistance between HO2S 4-pin connector terminals "C" and "D". (Scheme 43) Resistance should be about 6 ohms at 68°F (20°C). If resistance is not as specified, replace HO2S.

HO2S VOLTAGE (626 2.0L)

Scheme 43

1. Warm engine to normal operating temperature. Connect NGS scan tool to DLC-2. DLC-2 is located under left side of instrument panel, right of steering column. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD.
2. Turn ignition on. Select O2S11, O2S21, O2S12 or O2S22 PIDs to be checked and note voltage reading. See «HO2S PID IDENTIFICATION (626 2.5L)»(ref-12154-S20408273032000121300000) table. See VOLTAGE/PID VALUE CHARTS article. If voltage is not as specified, check wiring harness and connector between PCM and HO2S. Also check intake manifold system, fuel system and self-diagnostic system. Repair as necessary. If no problems are present, replace suspect HO2S.
3. To test HO2S heating element, allow sensor to cool to room temperature. Disconnect HO2S 4-pin connector. Using ohmmeter, measure resistance between HO2S 4-pin connector terminals "C" and "D" for rear HO2S. (Scheme 44) Resistance should be about 6 ohms at 68°F (20° C). If resistance is not as specified, replace HO2S.

HO2S PID IDENTIFICATION (626 2.5L)

Scheme 44

Miata, Millenia 2.5L & 626

Locate and remove IAT sensor from air cleaner housing. Place IAT sensor and thermometer in a container of water. Connect ohmmeter between IAT sensor terminals. Slowly heat water. Observe resistance at specified temperatures. See IAT SENSOR RESISTANCE SPECIFICATIONS (MIATA, MILLENIA 2.5L & 626) table. If resistance is not as specified, replace IAT sensor.

IAT SENSOR RESISTANCE SPECIFICATIONS (MIATA, MILLENIA 2.5L & 626)

1. Vehicle is equipped with 3 different IAT sensors. Each IAT sensor has unique resistance characteristics. One IAT sensor is located in air filter housing, another sensor is located in dynamic chamber at right rear of engine, and remaining IAT sensor is located in Lysholm compressor on top right of engine.
2. Remove IAT sensor(s) to be tested. Place IAT sensor and thermometer in a container of water. Connect ohmmeter between IAT sensor terminals. Slowly heat water. Observe resistance reading at specified temperatures. See «IAT SENSOR RESISTANCE SPECIFICATIONS (MILLENIA 2.3L)»(ref-12154-S41551744472000121300000) table. If resistance is not as specified, replace IAT sensor.

IAT SENSOR RESISTANCE SPECIFICATIONS (MILLENIA 2.3L)

IAT sensor is part of Mass Airflow (MAF) sensor. Disconnect MAF sensor connector. Using ohmmeter, measure resistance between MAF sensor terminals "A" and "F", located at each end of connector. See IAT SENSOR RESISTANCE SPECIFICATIONS (MPV) table. If resistance is not as specified, replace MAF sensor. Check for open or short on wiring between IAT sensor and PCM. Repair as necessary.

IAT SENSOR RESISTANCE (MPV)

IAT sensor is part of Mass Airflow (MAF) sensor. Disconnect MAF/IAT sensor connector. Using ohmmeter, measure resistance between MAF/IAT sensor terminals "D" and "E". (Scheme 45) See MAF/IAT SENSOR RESISTANCE SPECIFICATIONS (PROTEGE 1.6L) table. If resistance is not as specified, replace MAF/IAT sensor. If resistance is as specified, check for open between IAT sensor harness connector terminal "D" and PCM harness connector terminal No. 39 (Blue/White wire) or between IAT sensor harness connector terminal "E" and PCM harness connector terminal No. 91 (Orange wire). Check for short to ground between IAT sensor harness connector terminal "D" and PCM harness connector terminal No. 39 (Blue/White wire). Repair as necessary.

MAF/IAT SENSOR RESISTANCE SPECIFICATIONS (PROTEGE 1.6L)

Scheme 45

Remove IAT sensor. Using ohmmeter, measure resistance between IAT sensor terminals "A" and "B". (Scheme 46) See IAT SENSOR RESISTANCE (PROTEGE 2.0L) table. If not as specified, replace IAT sensor. If resistance readings are as specified, check for open in wiring between IAT sensor harness connector terminal "A" and PCM harness connector terminal No. 39 (Blue/White wire) or between IAT sensor harness connector terminal "B" and PCM harness connector terminal No. 91 (Orange wire). Check for short to ground between IAT sensor harness connector terminal "A" and PCM harness connector terminal No. 39 (Blue/White wire). Repair as necessary.

IAT SENSOR RESISTANCE SPECIFICATIONS (PROTEGE 2.0L)

Scheme 46

Miata, Millenia & 626 2.5L

Disconnect KS connector. Using ohmmeter, measure resistance between KS terminal "A" (White wire) and KS body. Resistance should be about 560,000 ohms at 68°F (20°C). If resistance is not as specified, replace KS.

Disconnect KS connector. Using ohmmeter, measure resistance between KS terminals "A" (Red wire) and "B" (Black wire). Resistance should be about 560,000 ohms at 68°F (20°C). If resistance is not as specified, replace KS.

Disconnect KS connector. Using ohmmeter, measure resistance between KS connector terminals "A" (Yellow/Blue wire) and "B" (Red wire). Resistance should be about 560,000 ohms at 68°F (20°C). If resistance is not as specified, replace KS.

1. MAP sensor is located in right rear of engine compartment. Connect NGS scan tool to DLC-2. DLC-2 is located under left side of instrument panel, right of steering column. Turn ignition on. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD. Select MAP V PID.
2. With 29.5 psi (100 kPa) of pressure applied to MAP sensor, voltage should be 4-5 volts. With 0 psi (0 kPa) of pressure applied to MAP sensor, voltage should be 2.4-2.9 volts. With 25.6 in. Hg of vacuum applied to MAP sensor, voltage should be .9-1.1 volts. If all voltage readings are as specified, MAP sensor is functioning properly. If any voltage reading is not as specified, go to next step.
3. Turn ignition off. Check continuity of following circuits: Black/Yellow wire between PCM harness connector terminal 3AB and MAP sensor harness connector terminal "A". Green/Orange wire between PCM harness connector terminal 3U and MAP sensor harness connector terminal "B". Light Green/Red wire between PCM harness connector terminal 3A and MAP sensor harness connector terminal "C". If continuity is present in all circuits, go to next step. If continuity is not present in one or more circuits, repair wiring harness as necessary. See WIRING DIAGRAMS article.
4. Turn ignition on. Measure voltage at MAP sensor harness connector terminal "B". Voltage should be a constant 4.5-5.5 volts. Measure voltage at MAP sensor harness connector terminal "A" (ground). Voltage should be less than one volt. If voltage is as specified, replace MAP sensor. If voltage is not as specified, repair wiring harness as necessary.

MASS AIRFLOW (MAF) SENSOR

1. Visually check MAF sensor for cracks or damage. If any damage is present, replace MAF sensor. If no damage is present, turn off all electrical loads. Connect New Generation Star (NGS) scan tool to DLC-2. Turn ignition on.
2. Using scan tool, select PID/DATA MONITOR AND RECORD function. Select MAF V PID and record value while operating vehicle under specified conditions. See «MASS AIRFLOW (MAF) SENSOR VOLTAGE»(ref-12154-S11607299052000121300000) table. If voltage is not as specified, check continuity of each circuit between MAF sensor and PCM. See WIRING DIAGRAMS article. Repair as necessary. If continuity is present in all circuits, replace MAF sensor.

MASS AIRFLOW (MAF) SENSOR VOLTAGE

Protege & 626

Disconnect neutral switch. Using ohmmeter, check continuity between switch terminals. Ensure continuity is present with transmission in Neutral (button on switch is pushed) and is not present in any other gear. Replace switch as necessary.

POWER STEERING PRESSURE (PSP) SWITCH

Disconnect PSP switch connector. Connect ohmmeter between PSP switch and ground. Start engine and operate at idle. Turn steering wheel from side to side and observe ohmmeter. Continuity should be present when steering wheel is fully turned. Continuity should not be present when steering wheel is straight ahead. If continuity is not as specified, replace PSP switch.

THROTTLE POSITION SENSOR

See ON-VEHICLE ADJUSTMENTS article for TP sensor testing and adjustment procedures.

TRANSMISSION RANGE SENSOR - 626 2.0L A/T

See appropriate TRANSMISSION SERVICE & REPAIR article for testing and adjustment procedures.

Except 626 2.0L A/T

1. Check for starter operation with ignition switch in START position and shift lever in "P" and "N" position only. Ensure back-up lights illuminate with ignition in ON position and selector lever in "R".
2. To test switch, disconnect transmission range switch connector. Check for continuity between specified terminals at transmission range switch. (Scheme 47), (Scheme 48), (Scheme 49), (Scheme 50) or (Scheme 51). If continuity is not as specified, replace switch.

Scheme 47

Scheme 48

Scheme 49

Scheme 50

Scheme 51

Miata, Millenia, Protege & 626

VSS is located on side of transaxle (transmission on Miata). Disconnect negative battery cable. Disconnect VSS connector. Rotate front wheels (rear wheels on Miata) and using analog voltmeter, measure voltage between sensor terminals. (Scheme 52) If voltmeter needle does not fluctuate, replace sensor.

Scheme 52

VSS is located on side of transaxle. Disconnect VSS connector. Remove VSS. Rotate gear and measure voltage (using analog voltmeter) between sensor terminals. (Scheme 52) If voltmeter needle does not fluctuate, replace sensor.

Note. The fuel pump relay housing is easily broken when relay is removed. Test relay in place and remove relay only for replacement.

Disconnect negative battery cable. Disconnect fuel pump relay 6-pin harness connector. FUEL PUMP RELAY LOCATIONS table. Check continuity between fuel pump relay terminals "A" and "B". (Scheme 53) Continuity should be present. Using fused jumper wires, connect positive battery terminal to fuel pump relay terminal "A". Connect negative battery terminal to fuel pump relay terminal "B". Continuity should be present between fuel pump relay terminals "C" and "E". Replace relay if continuity is not as specified.

Scheme 53

Millenia, Protege & 626

Remove fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. Using ohmmeter, check for continuity between relay terminals "C" and "D". (Scheme 54) Continuity should not be present. Using fused jumper wires, connect positive battery terminal to fuel pump relay terminal "A". Connect negative battery terminal to fuel pump relay terminal "B". Continuity should be present between fuel pump relay terminals "C" and "D". If continuity is not as specified, replace fuel pump relay.

Scheme 54

Remove fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. Using ohmmeter, check for continuity between relay terminals "C" and "E". (Scheme 55) Continuity should not be present. Using fused jumper wires apply battery voltage to terminal "A" and ground terminal "B". Continuity should be present between fuel pump relay terminals "C" and "E" with battery voltage applied. If continuity is not as specified, replace fuel pump relay.

FUEL PUMP RELAY LOCATIONS

Scheme 55

1. Fuel pump resistor and relay (speed) is located in left rear corner of engine compartment. Disconnect fuel pump resistor and relay connector. To check fuel pump resistor, measure resistance between relay terminals "A" and "B". (Scheme 56) Resistance should be.38-.42 ohm. If resistance is not as specified, replace fuel pump resistor and relay.
2. To check relay, check for continuity between terminals "E" and "F". (Scheme 56) Continuity should not be present. Using fused jumper wires, apply battery voltage to connector terminals "C" and "D". Continuity should be present between terminals "E" and "F". If continuity is not as specified, replace fuel pump resistor and relay (speed).

Scheme 56

MAIN RELAY

1. Ensure main relay clicks when ignition is turned on and off. If no sound is heard, locate and remove main relay from main fuse block, in left side of engine compartment. Using ohmmeter, check continuity between main relay terminals "C" and "D". (Scheme 54) Continuity should not be present.
2. Using fused jumper wires, apply battery voltage to main relay terminal "A" and ground terminal "B". Continuity should be present between main relay terminals "C" and "D". If continuity is not as specified, replace main relay.

Air By-Pass Valve (ABV) Vent Solenoid Valve - Millenia 2.3L

See AIR CHARGING PRESSURE CONTROL (MILLENIA 2.3L) under AIR INDUCTION SYSTEMS.

By-Pass Air Solenoid Valve - Millenia 2.3L

1. Solenoid valve is located in right rear of engine compartment. To identify solenoid valve, see appropriate illustration in VACUUM DIAGRAMS article. Disconnect vacuum hoses and connector from solenoid valve.
2. Apply air pressure to a solenoid valve port. Air should not flow through valve. Using fused jumper wires, apply battery voltage to solenoid valve terminals. Air should flow through valve. Replace solenoid valve as necessary.

Charge Air Cooler By-Pass Solenoid Valve - Millenia 2.3L

See AIR CHARGING PRESSURE CONTROL (MILLENIA 2.3L) under AIR INDUCTION SYSTEMS.

EGR Vent Solenoid Valve

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

EGR Vacuum Solenoid Valve

See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS & SUB-SYSTEMS.

Manifold Absolute Pressure (MAP) Sensor Solenoid Valve - Millenia 2.3L

Remove MAP sensor solenoid valve. MAP sensor solenoid valve is mounted on top of right shock tower. Apply air pressure to port "B" of MAP sensor solenoid valve. (Scheme 28) Air from port "B" should flow from "C" only. Using fused jumper wires, apply battery voltage to MAP sensor solenoid valve terminals. Apply air pressure to port "A" of MAP sensor solenoid valve. Air should flow from port "B" only. Replace MAP sensor solenoid valve as necessary.

Pressure Regulator Control (PRC) Solenoid Valve

Disconnect vacuum hose from PRC solenoid valve. See PRC SOLENOID VALVE LOCATIONS table. Apply air pressure to PRC solenoid valve port "B". (Scheme 57) Air should flow from port "C". Using fused jumper wires, apply battery voltage to solenoid terminals. Apply air pressure to PRC solenoid valve port "B". Air should flow through PRC solenoid valve air filter (port "A"). Replace PRC solenoid valve as necessary.

PRC SOLENOID VALVE LOCATIONS

Scheme 57

Purge Control Solenoid

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

VICS Solenoid

See appropriate VARIABLE INERTIA CHARGING SYSTEM (VICS) under AIR INDUCTION SYSTEMS .

VRIS Solenoid

See VARIABLE RESONANCE INDUCTION SYSTEM (VRIS) - MILLENIA 2.5L & 626 2.5L under AIR INDUCTION SYSTEMS.

FUEL PRESSURE RELEASE

Remove fuel filler cap. Disconnect fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. Start engine (if possible) and allow to die. Crank engine several times. Turn ignition off. Reconnect fuel pump relay. Reinstall fuel filler cap.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC DIAGNOSTIC PROCEDURES article.

Fuel Pump Circuit

See FUEL PRESSURE under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article.

Fuel Pressure Regulator

See FUEL PRESSURE under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article.

Pressure Regulator Control Solenoid

See PRESSURE REGULATOR CONTROL (PRC) SOLENOID VALVE under SOLENOIDS.

Fuel Injectors

Using stethoscope, listen for normal clicking sound at each injector during idle and acceleration. If clicking sound is not heard, check injector wiring circuit, or main relay and circuit.

Fuel Injector Leakage

1. Using mechanics wire, secure each fuel injector to fuel rail. Disconnect fuel injector connectors. Remove fuel rail assembly from intake manifold. See REMOVAL, OVERHAUL & INSTALLATION article. Reconnect fuel lines to fuel rail. Locate underhood DLC-1 in left side of engine compartment.
2. Connect a fused jumper wire between underhood DLC-1 terminals F/P and GND. (Scheme 58) Turn ignition on. Tilt injectors about 60 degrees and check injector nozzles for fuel leaks. Fuel leakage should be less than one drop every 2 minutes. If fuel leakage is present, replace injector.

Scheme 58

Fuel Injector Resistance - Except Millenia

Disconnect fuel injector connector. Using ohmmeter, measure resistance between injector terminals. See FUEL INJECTOR RESISTANCE SPECIFICATIONS table. Replace injectors as necessary.

FUEL INJECTOR RESISTANCE SPECIFICATIONS

Fuel Injector Resistance (Millenia)

Disconnect fuel injector connectors. Using ohmmeter, measure resistance between injector terminals. See FUEL INJECTOR RESISTANCE SPECIFICATIONS and FUEL INJECTOR TERMINAL IDENTIFICATION (MILLENIA) tables. (Scheme 59) Replace injectors as necessary.

FUEL INJECTOR TERMINAL IDENTIFICATION (MILLENIA)

Scheme 59

Fuel Injector Volume - Miata

1. Disconnect battery. Remove fuel rail assembly and injectors from intake manifold. See REMOVAL, OVERHAUL & INSTALLATION article.
2. Using mechanics wire, secure each fuel injector to fuel rail. Disconnect fuel injector connectors. Reconnect fuel lines to fuel rail.
3. Using Service tool (49L018901), connect battery to each injector in turn. Using a fused jumper wire, connect DLC-1 connector terminals F/P and GND. Turn ignition on for 15 seconds. Measure fuel injector volume.
4. If injector output volume is less than 68-88 cc's, replace suspect injector, then check next injector. If injector output volume is 68-88 cc's or more, check next injector.
5. When all injectors have been checked, reinstall all components. recheck system.

Fuel Injector Volume - MPV

Disconnect battery. Remove fuel rail assembly and injectors from intake manifold. See REMOVAL, OVERHAUL & INSTALLATION article. Using a fuel injector tester, check each injector output for 15 seconds. If injector output volume is not 44-58 cc's, replace suspect injector.

Fuel Cut Control System - Miata

1. To check system operation, connect New Generation Star (49 T088 0A0) scan tool to DLC-2. DLC-2 is located under left side of instrument panel, behind fuse block cover. Ensure engine is at normal operating temperature. Allow engine to idle. Turn A/C switch off.
2. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD. Select RPM and INJ. Scan tool will measure and display fuel injector pulse width. Increase engine speed to 2500 RPM, then quickly close throttle valve.
3. Fuel injection pulse width should be zero milliseconds until engine speeds drops below 1000 RPM, then pulse width should be 2-5 milliseconds. If pulse width is as specified, Fuel cutoff system is functioning properly.

Fuel Cut Control System - Millenia 2.5L & 626

1. Warm up engine to normal operating temperature and let idle.
2. Increase engine speed to 3000 RPM, then quickly release throttle.
3. Using screwdriver or stethoscope, listen to each fuel injector for operating sound. Ensure that injectors are not operating above about 2500 RPM.

SYSTEM CHECK - MPV

1. Ensure engine is at ambient temperature. Connect scan tool. Using PID/DATA monitor and record function, select ECT, IAC V and RPM PIDs. Start engine.
2. Engine speed should decrease as engine reaches operating temperature. If idle speed decreases, go to next step. If engine speed does not decrease, check ECT sensor, IAC valve and wiring.
3. Allow engine to warm to operating temperature. Check for DTC P0506, P0507 and P1504. If no DTCs are present, go to next step. If any DTCs are present, diagnose and repair as necessary.
4. Using scan tool, select SIMULATION TEST. Change duty value of IAC valve to 100 percent. If idle speed increases, go to next step. If idle speed does not increase, check IAC valve passages and wiring.
5. Using scan tool PID/DATA monitor and record function, select A/C SW, ALTF, IAC V, PSP SW, RPM and RPM DES PIDs. Ensure idle speed stays in specification when accessories are operated. See «IDLE SPECIFICATIONS»(ref-12154-S06776926782000121300000) table. If idle speed is okay, check is complete. If idle speed is not okay, check suspect component and circuit.

IDLE SPECIFICATIONS

BY-PASS AIR CONTROL (BAC) VALVE (MILLENIA)

1. On Millenia 2.3L, BAC valve is located on rear of front cylinder head. (Scheme 60) On Millenia 2.5L, BAC valve is located underneath throttle body. (Scheme 61)
2. On all models, ensure engine is cold. Start engine and let it idle. Idle speed should gradually decrease as engine reaches normal operating temperature. If idle speed does not decrease, check coolant hose to BAC valve. Repair as necessary. If coolant hose is okay, replace BAC valve.

Scheme 60

Scheme 61

Miata, MPV, Protege & 626

Disconnect IAC valve connector. Using an ohmmeter, measure resistance between IAC valve terminals. See IAC VALVE RESISTANCE SPECIFICATIONS table. If resistance is not within specification, replace IAC valve.

IAC valve is part of By-Pass Control (BAC) valve. Disconnect IAC valve connector. Using an ohmmeter, measure resistance between IAC valve terminals. See IAC VALVE RESISTANCE SPECIFICATIONS table. If resistance is not as specified, replace BAC valve.

IAC VALVE RESISTANCE SPECIFICATIONS

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC DIAGNOSTIC PROCEDURES article.

System Check - Except Miata, MPV & Protege

Check all connectors and vacuum hose routing. Check for cracks, leakage and restrictions, and repair as necessary. Start engine and operate throttle. Diaphragm of EGR control valve should not move while engine is cold. Warm engine to operating temperature. Increase engine speed to about 2000 RPM, EGR control valve diaphragm should move. If no movement is detected, check EGR system components.

System Check - Miata & MPV

1. While listening to EGR valve, turn ignition on. If initial operation of EGR valve is present, go to next step. If initial operation of EGR valve is not present, check for DTCs. See appropriate SELF-DIAGNOSTICS article. Check EGR valve. See «EGR VALVE (MIATA, MPV, PROTEGE & 626)»(ref-12154-S28899096182000121300000) .
2. Start engine. Connect scan tool and select SIMULATION TEST. Using scan tool, increase EGR step value from 0 to 40. If idle speed does not change, go to next step. If engine stumbles or stalls, go to step 4 .
3. Turn ignition off. Remove EGR valve. Reconnect EGR electrical connector. Turn ignition on. Using scan tool, increase EGR step value from 0 to 40. If EGR valve operates, clean EGR valve and passages. Install and retest. If EGR valve does not operate, replace EGR valve and retest.
4. Warm engine to operating temperature. Raise and support vehicle with drive wheels off the ground, or place vehicle on a chassis dynamometer. Using scan tool, select PID/DATA MONITOR AND RECORD function. Select SEGRP, RPM, VS, TP V, and ECT V PIDs. Start engine and allow vehicle to idle in gear. Ensure SEGRP PID is 0. Increase engine speed and check SEGRP. If SEGRP does not change, go to next step. If SEGRP changes, go to step 6 .
5. Check TP PID value for increase when throttle is depressed. Check VS PID value for increase when vehicle speed is increased. Check ECT PID for proper voltage when engine is at operating temperature. If any problem is present, repair component or wiring as necessary and retest.
6. Stop vehicle. Check SEGRP PID at idle. Ensure SEGRP PID is 0.

System Check - Protege

Disconnect negative battery cable. Inspect EGR valve system vacuum hoses for improper routing, kinks or leaks. Using ohmmeter, measure resistance between EGR valve terminals "C" and "E", "C" and "A", "D" and "B" and between "D" and "F". (Scheme 64) Resistance reading should be 20-24 ohms. If resistance readings are not as specified, replace EGR valve. If readings are as specified, check wire harness between EGR valve and PCM for short or open circuit. See WIRING DIAGRAMS article. Repair as necessary.

Note. Millenia 2.3L & Miata models are not equipped with EGR Boost Sensor

1. Connect NGS scan tool to DLC-2. DLC-2 is located under left side of instrument panel. Turn ignition on. Using scan tool, access DIAGNOSTIC DATA LINK menu, and select PCM. Highlight and select PID/DATA MONITOR AND RECORD. Select BARO V PID.
2. Ensure BARO V PID is within specification. Voltage should be 2.3-4.7 volts. If BARO voltage is not as specified, locate and repair open or short circuit in wire harness between EGR boost sensor and PCM. (Scheme 62) See WIRING DIAGRAMS article. If voltage is as specified, go to next step.
3. Apply vacuum to EGR boost sensor and monitor BARO voltage. If vacuum is exceeded, EGR boost sensor will be damaged. Voltage should vary between 0.8-1.3 volts. If voltage readings vary as vacuum is applied, EGR boost sensor is functioning properly. If voltage readings do not vary as vacuum is applied, replace EGR boost sensor.

Scheme 62

EGR Boost Solenoid

Note. Millenia 2.3L models are not equipped with EGR Boost Solenoid.

Remove EGR boost solenoid. See EGR BOOST SOLENOID LOCATIONS table. Apply air pressure to port "B" of solenoid valve. (Scheme 28) Air should flow from port "C" only. Using fused jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to port "A" of solenoid valve. Air should flow from port "B" only. Replace solenoid valve as necessary.

EGR BOOST SOLENOID LOCATIONS

EGR Position Sensor - Millenia

EGR position sensor is part of EGR valve. Disconnect EGR position sensor connector. Disconnect vacuum hose from EGR control valve. Measure resistance between EGR position sensor terminals. See EGR POSITION SENSOR RESISTANCE SPECIFICATIONS table. (Scheme 63) Apply 5.9 in. Hg of vacuum to EGR position sensor and recheck resistance. If resistance is not as specified, replace EGR valve.

EGR POSITION SENSOR RESISTANCE SPECIFICATIONS

Scheme 63

EGR Vacuum Solenoid Valve - Millenia

Remove EGR vacuum solenoid. See EGR VACUUM/VENT SOLENOID VALVE LOCATIONS table. Apply air pressure to a EGR vacuum solenoid valve port. (Scheme 65) Air should not flow from other EGR vacuum solenoid port. Using fused jumper wire, apply battery voltage to EGR vacuum solenoid valve terminals. Air should flow with voltage applied. If EGR vacuum solenoid valve does not operate as specified, replace valve.

EGR Valve - Miata, MPV, Protege & 626

1. Using a stethoscope, listen for EGR valve initialization noise (clicks) when starting and stopping engine. If clicking noise is heard, EGR valve is functioning properly. If clicking noise is not heard, go to next step.
2. Turn ignition off. Disconnect EGR valve connector. Using an ohmmeter, measure resistance between EGR valve terminals "C" and "E", "C" and "A", "D" and "B" and between "D" and "F". (Scheme 64) Each resistance reading should be about 22 ohms. On Protege, resistance reading should be 20-24 ohms.
3. If resistance is as specified, check wiring harness between EGR valve and PCM. See WIRING DIAGRAMS article. If resistance is not as specified, replace EGR valve.

Scheme 64

EGR Valve - Millenia

Warm engine to normal operating temperature and operate at idle. Disconnect and plug vacuum hose at EGR valve. Engine should run smoothly. Connect vacuum pump to EGR valve, and apply vacuum. Engine should run rough or stall. If engine does not operate as specified, replace EGR valve.

EGR Vent Solenoid Valve - Millenia

Remove EGR vent solenoid valve. See EGR VACUUM/VENT SOLENOID VALVE LOCATIONS table. Apply air pressure to port "A". (Scheme 65) Air should flow from ports "B" and "C". Using fused jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to port "A". Air should flow from port "B" only. Replace solenoid valve as necessary.

EGR VACUUM/VENT SOLENOID VALVE LOCATIONS

Scheme 65

FUEL EVAPORATION (EVAP) SYSTEM - EXCEPT MPV

Note. For DTC related procedures, see appropriate SELF-DIAGNOSTICS article.

Charcoal Canister - Miata & Protege

Remove charcoal canister. On Miata, charcoal canister is located under vehicle, forward of fuel tank. On Protege, charcoal canister is located in right rear of engine compartment. Plug ports "A" and "B". Apply small amount of air pressure to port "C". On Protege, plug ports "A" and "C". Apply small amount of air pressure to port "B". (Scheme 66) If air leaks, replace charcoal canister.

Scheme 66

Charcoal Canister - Millenia

Charcoal canister is located under rear of vehicle. Plug Canister Drain Cut Valve (CDCV) port and purge solenoid valve port. (Scheme 67) Apply small amount of air pressure to fuel tank port on charcoal canister. If air leaks, replace charcoal canister.

Scheme 67

Charcoal Canister - 626

Remove hoses from charcoal canister. Charcoal canister is located under vehicle, below spare tire well. Plug ports "A" and "B". Apply small amount of air pressure to port "C". If air leaks, replace charcoal canister.

Catch Tank - Miata, MPV & Protege

Remove catch tank. See CATCH TANK LOCATIONS table. Plug one port and apply small amount of air pressure into other port on catch tank. Check for leaks. Replace if any leaks are present.

CATCH TANK LOCATIONS

One-Way Check Valve - Millenia

One-way check valve is located on top of fuel tank. Note direction of valve installation. Remove check valve. Apply air pressure to one-way check valve port "A". (Scheme 68) Air should flow from port "B". Apply air pressure to port "B". Air should not flow from port "A". If check valve does not operate as specified, replace one-way check valve.

Scheme 68

2-Way Check Valve - Millenia, Protege & 626

Remove check valve, located at rear of vehicle by fuel filler. Using SST, apply +0.99 kPa of air pressure to port "A". (Scheme 69) Air should flow from port "B". Apply air pressure to port "C". Air should flow from port "A". If not as specified, replace 2-way check valve.

Scheme 69

Fuel Shut-Off/Rollover Valve - Miata

Vehicle is equipped with 2 fuel shut-off/rollover valves located in top of fuel tank. Fuel shut-off/rollover valves are part of fuel tank. Remove fuel tank. Plug main fuel pipe, return pipe of fuel pump unit and port "A"of fuel tank. (Scheme 70) Level fuel tank. Using SST 49-U014-001, blow air through port "B" and ensure air flows from port "A". If no air flow is present from port "A", replace fuel tank. If air flow is present, unplug port "C" and turn fuel tank upside down. With fuel tank turned upside down, use SST 49-U014-001 and blow air through port "B". Ensure air does not flow from ports "A" and "C". If fuel shut-off/rollover valves do not operate as specified, replace fuel tank.

Scheme 70

Fuel Vapor Rollover Valve - Millenia

Vehicle is equipped with 2 fuel vapor valves, built into top of fuel tank. With fuel vapor rollover valve in upright position, air should flow through valve. With fuel vapor rollover valve turned upside down (with fuel tank), air should not flow through valve. If fuel vapor rollover valve does not operate as specified, replace fuel tank.

Fuel Vapor Rollover Valve - Protege

Vehicle is equipped with 2 fuel shut-off/rollover valves located in top of fuel tank. Fuel shut-off/rollover valves are part of fuel tank. Remove fuel tank. Plug main fuel pipe, return pipe of fuel pump unit and port "A"of fuel tank. (Scheme 71) Level fuel tank. Using SST 49-U014-001, blow air through port "B" and ensure air flows from port "C". If no air flow is present from port "C", replace fuel tank. If air flow is present, connect SST to port "C" and plug port "A". Apply air pressure using SST 49-U014-001 to port "C". Air should flow from port "B". If air flow is not present at port "B", replace fuel tank. If air flow is present, connect SST 49-U014-001 to port "B" and turn fuel tank upside down. With fuel tank turned upside down, blow air through port "B". Ensure air does not flow from port "C". If valve does not operate as specified, replace fuel tank.

Scheme 71

Fuel Vapor Rollover Valve - 626

Two fuel vapor rollover valves are located in top of fuel tank. Remove fuel vapor valve. It may be necessary to remove fuel tank to access valve. Hold valve in level upright position. Blow air into port (hose barb). Air should flow through valve to lower port. Turn valve upside down. Air should not flow through valve. Replace valve as necessary.

Purge Control Solenoid Valve

Disconnect purge control solenoid valve connector. See PURGE CONTROL SOLENOID VALVE LOCATIONS table. Ensure air does not flow through purge control solenoid valve vacuum ports. Using fused jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to a solenoid valve port. Air should flow from other port. If solenoid valve does not operate as specified, replace purge control solenoid valve.

PURGE CONTROL SOLENOID VALVE LOCATIONS

FUEL EVAPORATION (EVAP) SYSTEM - MPV

Note. For DTC related procedures, see appropriate SELF-DIAGNOSTICS article.

Fuel Tank Pressure Graphing

Connect scan tool to DLC-2. DLC-2 is located under left side of instrument panel, left of steering column. Select PID/DATA MONITOR AND RECORD function. Select CDCV and FTP PIDs. Press start to view PIDs. Perform drive mode 4. Press TRIGGER to capture data when starting drive mode. When PCM monitors EVAP system, PID will change from OFF to ON. After test is complete, PID will change to OFF. Wait a few seconds, then press TRIGGER. Select VIEW RECORDING and press TRIGGER. Select CDCV and FTP PIDs. Press GRAPH. Use No. 8 key to advance to point when CDCV was turned on. Compare graph to normal and abnormal patterns. (Scheme 72) Diagnose and repair as necessary.

Scheme 72

Air Filter

Remove air filter, located next to left front shock tower. Blow through filter in both directions. If air flows in both directions, filter is okay. If air does not flow in both directions, replace filter.

Fuel Shut-off/Rollover Valve

1. Clean area around quick release connector. Disconnect fuel lines and wiring from fuel tank. Remove fuel tank with pump. Plug main fuel and return lines at pump. Plug ports "A" and "D". (Scheme 73)
2. Blow through port "B". If air flows out of port "C", remove port "A" plug and go to next step. If air does not flow out of port "C", replace tank.
3. Plug ports "C" and "D". Blow through port "B". If air flows out of port "A", remove port "C" plug and go to next step. If air does not flow out of port "A", replace tank.
4. Turn tank upside down. Blow through port "B". If air flows out of ports "A" or "C", replace tank. If air does not flow out of ports "A" or "C", test is complete.

Scheme 73

Disconnect purge control solenoid valve connector, located next to air inlet. Ensure air flows through solenoid valve vacuum ports "B" and "C". Using fused jumper wires, apply battery voltage to solenoid valve terminals. Apply air pressure to a solenoid valve port "B". Air should flow from port "A". If valve does not operate as specified, replace solenoid valve.

Vent Cut Valve

Note. Testing information not available from manufacturer.

Coil Resistance

1. Disconnect Oil Control Valve (OCV) harness connector.
2. Using DVOM, measure resistance between OCV terminals. Resistance reading should be 6.9-7.9 ohms.
3. If resistance reading is not as specified, replace OCV.

Scheme 74

1. Remove the Oil Control Valve (OCV). See «OIL CONTROL VALVE»(ref-134974-S23228190112002092000000) under VARIABLE VALVE TIMING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article.
2. Ensure spool valve (in OCV) is in maximum valve timing retard position. (Scheme 74) If not as specified, replace OCV.
3. Ensure battery is fully charged.
4. Using fused jumper wires, apply battery voltage between OCV terminals and ensure spool valve moves to maximum valve timing advance position. (Scheme 74) If OCV operation is not as specified, replace OCV. NOTE: When applying battery voltage between OCV terminals, connection can be either of following: Positive battery cable to terminal "A". Negative battery cable to terminal "B". Positive battery cable to terminal "B". Negative battery cable to terminal "A".
5. Disconnect fused jumper wires and verify spool valve returns to maximum valve timing retard position. (Scheme 74) If OCV does not operate as specified, replace OCV.

Scheme 75

1. Disconnect the negative battery cable.
2. Remove the timing belt. See TIMING BELT under REMOVAL & INSTALLATION in appropriate ENGINES article.
3. Hold hexagonal part of the intake camshaft with an adjustable wrench to prevent camshaft from rotating. (Scheme 75) Attempt to rotate Variable Valve Timing (VVT) actuator by hand and ensure it does not move. If VVT actuator moves, stopper pin in VVT actuator is not operating. Replace VVT actuator.
4. Install timing belt. See TIMING BELT under REMOVAL & INSTALLATION in appropriate ENGINES article.

Scheme 76

1. Disconnect negative battery cable.
2. Remove Variable Valve Timing (VVT) actuator. CAUTION: If engine oil gets on parts, they may not function properly. When removing VVT actuator, be sure to cover other parts with a cloth to protect them from oil.
3. Ensure camshaft dowel pin hole on VVT actuator is aligned with top of third tooth, by counting back 3 teeth to sprocket gap which is aligned with alignment mark. (Scheme 76) If not as specified, stopper pin in VVT actuator is not engaged at position of maximum valve timing retard. Replace VVT actuator.
4. Install VVT actuator.

MISCELLANEOUS CONTROLS

Note. Although some of the controlled devices listed here are not technically engine performance components, they can affect driveability if they malfunction.

A/C Clutch Relay

For detailed A/C clutch diagnostic procedures, see appropriate MANUAL A/C-HEATER SYSTEMS or AUTOMATIC A/C HEATER SYSTEMS articles.

1-Speed Motor

1. Ensure battery is fully charged. Disconnect cooling fan motor connector. Connect ammeter between positive battery terminal and positive cooling fan motor connector. Ground negative cooling fan terminal. See appropriate wiring diagram under WIRING DIAGRAMS in ELECTRIC COOLING FANS article.
2. Ensure cooling fan motor operates smoothly at specified current. See «COOLING FAN MOTOR CURRENT SPECIFICATIONS»(ref-12154-S03085464682001062800000) table. If cooling fan motor draws more or less than specified amperage, check wiring. If wiring is okay, replace cooling fan motor.

COOLING FAN MOTOR CURRENT SPECIFICATIONS

2-Speed Or 3-Speed Motor

1. Ensure battery is fully charged. Disconnect cooling fan motor connector. Connect ammeter between positive battery terminal and positive cooling fan motor connector terminal for desired fan speed test. See appropriate wiring diagram under WIRING DIAGRAMS in ELECTRIC COOLING FANS article.
2. Ensure cooling fan motor operates smoothly on all speeds at specified current. See «COOLING FAN MOTOR CURRENT SPECIFICATIONS»(ref-12154-S03085464682001062800000) table. If cooling fan motor draws more or less than specified amperage, check wiring. If wiring is okay, replace cooling fan motor.

Cooling Fan Relay

For diagnostic procedures, see appropriate MANUAL A/C-HEATER SYSTEMS, AUTOMATIC A/C HEATER SYSTEMS or COOLING FAN articles.