System/component Tests - v6 Mazda MPV V

INTRODUCTION

Note. Prior to testing separate components or systems, it is highly recommended that all procedures listed in appropriate BASIC TESTING article be performed. Since many computer controlled and monitored components will set a trouble code if they malfunction, it is also recommended that self diagnosis be performed. See appropriate TESTS W/CODES article.

System Inspection

Warm engine to normal operating temperature. Run engine at idle. Verify swirl control valve actuator rod is retracted into swirl control valve. (Scheme 51) Gradually increase engine speed and verify rod extends at speeds above 4000 RPM. If necessary, check following components.

Scheme 51

Swirl Control Valve Actuator

Disconnect vacuum hose to swirl control valve actuator and connect a vacuum pump to actuator. (Scheme 51) Apply 7.87 in. Hg and verify rod fully retracts into actuator. If rod fails to retract, replace actuator.

Vacuum Signal

Disconnect vacuum hose from swirl control valve actuator. (Scheme 51) Place finger over hose and verify vacuum is felt at idle. Gradually increase engine speed and verify no vacuum is felt above 4000 RPM. Reconnect vacuum hose to actuator.

Electrical Signal

Connect a voltmeter to the Blue/Red terminal of the TICS control solenoid valve. (Scheme 52) Gradually increase engine speed and check voltmeter reading. Below 4000 RPM, voltage should be less than 2.0 volts. Above 4000 RPM, voltage should be approximately 12 volts.

Scheme 52

Solenoid Valve

Disconnect vacuum hose from solenoid valve port "A". Blow through solenoid valve from hose "B". (Scheme 53) Verify air flows from valve air filter. Disconnect solenoid valve connector and connect 12 volts and a ground to solenoid valve terminals. (Scheme 53) Blow through solenoid valve hose "B". Verify air passes through solenoid valve and flows from port "A".

Scheme 53

Swirl Control Valve Arm

Remove swirl control valve actuator. Rotate swirl control valve arm and verify swirl control valve moves freely. If necessary, replace intake manifold assembly.

Warm engine to normal operating temperature. Run engine at idle. Remove protector from shutter valve actuator. Verify shutter valve actuater rod is extended at idle. Gradually increase engine speed and verify rod retracts into shutter valve actuator at engine speeds above 3700 RPM. Continue to increase engine speed and verify rod extends above 5750 RPM. (Scheme 54) If necessary, check following components.

Scheme 54

Disconnect vacuum hose from shutter valve actuator. (Scheme 54) Place a finger over hose and ensure vacuum is felt between 3700 RPM and 5750 RPM. Reconnect vacuum hose to actuator.

Voltage Signal

Connect voltmeter to Brown/White terminal of solenoid valve. (Scheme 55) Check voltmeter reading is within specifications throughout RPM range. Replace solenoid valve if necessary. See VARIABLE RESONANCE INDUCTION SYSTEM RPM VOLTAGES table.

VARIABLE RESONANCE INDUCTION SYSTEM RPM VOLTAGES

Scheme 55

Disconnect vacuum hose from solenoid valve port "A". Blow through port "B". Verify air flows from valve air filter. (Scheme 53) Disconnect solenoid valve electrical connector and connect 12 volts and a ground to terminals of solenoid valve. Blow through valve from hose "B" and ensure air flows from port "A". Replace if necessary.

Shutter Valve Actuator

Remove shutter valve actuator. Connect a vacuum pump to shutter valve actuator. Apply vacuum and verify rod is pulled into actuator. Replace shutter valve actuator if rod fails to retract. With shutter valve actuator removed, ensure shutter valve control arm moves smoothly. (Scheme 56) Replace if necessary.

Scheme 56

A/C SWITCH

See A/C CUT-OUT CONTROL SYSTEM under RELAYS, SOLENOIDS, MOTORS & MOTORS.

MPV 3.0L & 929

Inspect airflow meter for damage and ensure measuring plate moves smoothly. (Scheme 57) Disconnect airflow meter connector. Measure resistance using AIRFLOW METER TERMINAL RESISTANCE table.

AIRFLOW METER TERMINAL RESISTANCE

Scheme 57

Testing

1. Remove vacuum hose on sensor. Turn ignition on and check voltage between terminal "A" and ground, and "B" and ground. Observe voltmeter while applying and releasing vacuum.
2. Voltage at terminal "B" should be about 4.5-5.5 volts. Voltage at terminal "A" should be less than 1.5 volts. If voltage at terminals "A" or "B" is not correct, check wiring harness. If voltage fluctuates, replace atmospheric pressure sensor.
3. Measure voltage between terminal "D" and ground. Depending on altitude, voltage at terminal "D" should be 3.5-4.5 volts at sea level and 2.5-3.5 volts at 6500 feet. If voltage at terminal "D" is incorrect, replace atmospheric pressure sensor. (Scheme 58)

Scheme 58

BRAKE LIGHT SWITCH

Disconnect brake light switch connector. Measure resistance between terminals of brake light switch. With brake pedal released, resistance should be infinite. With brake pedal depressed, resistance should be zero ohms.

CLUTCH SWITCH

Remove connector from switch. Connect ohmmeter to switch terminals. Check that continuity exists with clutch pedal depressed and no continuity exists with pedal released. Replace switch if continuity is not correct.

COOLANT THERMOSENSOR

1. Remove thermosensor. Place thermosensor in container of heated coolant with thermometer.
2. Connect ohmmeter to thermosensor terminals. Note resistance at specified temperatures. See «COOLANT THERMOSENSOR RESISTANCE»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) table. Replace if not within specification.

COOLANT THERMOSENSOR RESISTANCE

COOLANT TEMPERATURE SWITCH

1. Remove switch from radiator. Place switch in container of heated coolant with thermometer.
2. Connect ohmmeter to switch terminals. Note temperature at which continuity exists between switch terminals. Continuity should exist with coolant temperature above 63°F (17°C). Replace switch if not within specification.

CRANK ANGLE SENSOR

See IGNITION TESTING in BASIC TESTING article.

EGR POSITION SENSOR (929)

For testing procedures, see EGR SYSTEM under EMISSION SYSTEMS and SUB-SYSTEMS.

All Except MPV

1. Connect a voltmeter between control unit and ground. Start engine. Check voltage at terminals using ELC UNIT VOLTAGE chart under «VOLTAGE CHARTS»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) .
2. If voltages are incorrect, check the appropriate circuit. If voltages are okay, replace ELC.

MPV

1. Remove the ELC from behind left side of instrument panel. Check voltage at terminals of ELC connector using ELC UNIT VOLTAGE chart under «VOLTAGE CHARTS»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) .
2. If voltages are incorrect, check the appropriate circuit. If voltages are okay, replace ELC.

Scheme 59

Scheme 60

INTAKE AIR SENSOR (DYNAMIC CHAMBER)

Disconnect intake air temperature sensor connector. Measure resistance of sensor using INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. (Scheme 61)

Scheme 61

INTAKE AIR TEMPERATURE SENSOR RESISTANCE

1. Disconnect connector near transmission. Place transmission in Neutral position. Resistance across switch should be infinite.
2. Place transmission in any gear. Resistance across switch should be zero ohms. If necessary, replace switch.

OXYGEN SENSOR (O2)

1. Warm engine to operating temperature. Run engine at fast idle. Disconnect O2 sensor. Connect a high impedance voltmeter between O2 sensor and ground.
2. Observe voltmeter while rapidly accelerating and decelerating engine speed. Replace O2 sensor, if voltage is not .5-1.0 volt while accelerating and 0-.4 volt while decelerating. Ensure new oxygen sensor has anti-seize compound applied to threads. Tighten sensor to 22-36 ft. lbs. (29-49 N.m).

POWER STEERING SWITCH

1. Start engine and allow to idle. Remove connector from switch. Connect ohmmeter to switch terminals. Turn steering wheel from side to side and note continuity reading.
2. Continuity should exist with front wheels turned but should not exist with wheels straight ahead. Replace switch if continuity is not correct.

PULSATION DAMPER

Start engine and run at idle. Pulsation damper is located at end of fuel rail. Place finger over pulsation damper and ensure damper pulsates. Replace pulsation damper if no operation exists.

STOPLIGHT SWITCH

Stoplight switch is located at top of brake pedal. Switch should show continuity when brake pedal is depressed.

THROTTLE POSITION SENSOR

See ADJUSTMENTS article for checking and adjustment procedures.

VEHICLE SPEED SENSOR

See PIN VOLTAGE CHART S article and SENSOR RANGE CHARTS charts article.

Operation

The A/C clutch relay is opened (disengages A/C clutch), for 7 seconds during the following conditions: blower and A/C switch on, transmission in gear, clutch pedal released and throttle opened more than half way.

1. Turn A/C, blower and ignition switches on. DO NOT start engine. Shift transmission into a drive gear. Open throttle fully. Listen for A/C clutch disengaging and reengaging after 7 seconds.
2. If system does not test as indicated, check operations of related switches and relays. See PIN VOLTAGE CHART S and SENSOR RANGE CHARTS articles.

AIR INJECTION SOLENOIDS

For all related control solenoids, see SECONDARY AIR INJECTION under EMISSION SYSTEMS and SUB-SYSTEMS.

AIR INDUCTION CONTROLS

For all related control solenoids, see AIR INDUCTION.

CIRCUIT OPENING RELAY

See FUEL CONTROL CIRCUIT in BASIC TESTING article for test procedures.

COIL WITH IGNITOR

See IGNITION SYSTEM in BASIC TESTING article for test procedures.

EGR SOLENOID (929)

For testing procedures, see EGR SYSTEM under EMISSION SYSTEMS and SUB-SYSTEMS.

FUEL INJECTORS

1. Using stethoscope, listen for normal "clicking" sound at each injector during idle and acceleration.
2. Start engine and slowly increase engine speed. Using stethoscope, check that operating sound of secondary injectors occurs above 3500 RPM. If clicking sound is not heard, check crank angle sensor resistance, wiring from crank angle sensor to ECU and EGI main fuse.

Injector Resistance

Remove electrical connector from injector. Using ohmmeter, measure resistance between injector terminals. Replace injector if resistance is not within specifications.

FUEL INJECTOR RESISTANCE

HOT START RELAY

See HOT START SYSTEM in the FUEL SYSTEM section.

MAIN RELAY

1. Ensure main relay clicks when ignition is turned on and off.
2. If no sound is heard, unplug relay. Apply 12 volts to terminal A and ground terminal B. (Scheme 62)
3. Use ohmmeter to check terminal continuity. Terminals C-D should have continuity with 12 volts applied. There should be no continuity with no voltage applied. If relay does not respond as described, replace the main relay.

Scheme 62

OXYGEN SENSOR RELAY (MPV 3.0L & 929)

1. Ensure there is a clicking sound heard at oxygen sensor relay when ignition is turned on and off. Apply 12 volts to terminal "A" and ground terminal "B". (Scheme 63)
2. Measure resistance between terminals "C" and "D". With 12 volts applied, resistance should be zero ohms. With no voltage applied, resistance should be infinite.

Scheme 63

PRESSURE REGULATOR CONTROL SOLENOID

1. Unplug vacuum hose from pressure regulator control solenoid. Blow through solenoid from port A. Ensure air flows through port B. (Scheme 64)
2. Unplug solenoid valve connector. Connect 12 volts and ground to solenoid terminals. (Scheme 64) Blow through solenoid from port A. Air should exhaust through the valve air filter. Replace solenoid valve if it does not pass test.

Scheme 64

PURGE CONTROL SOLENOIDS

For testing procedures, see EVAPORATION CONTROL under EMISSION SYSTEMS AND SUB-SYSTEMS.

TICS SOLENOID

See AIR INDUCTION.

VRIS SOLENOID

See AIR INDUCTION.

WASTEGATE SOLENOID

See AIR INDUCTION.

FUEL DELIVERY

Note. For fuel system pressure testing, see BASIC TESTING article.

Injector Fuel Leakage

1. Remove dynamic chamber, if necessary. Loosen delivery pipe attaching bolts. Remove delivery pipe. Using wire, secure injectors tightly onto delivery pipe. CAUTION: Ensure injectors are securely tied to delivery pipe. If not properly secured, fuel may spray from loose connections.
2. Install jumper wire between 2 terminals of fuel pump test circuit connector. See BASIC TESTING article for test connector location. Turn ignition on. Check that no fuel leakage exists at injectors. After 5 minutes, only a slight amount of fuel leakage is acceptable.

Injector Delivery Volume

1. Using wire, secure injectors tightly onto delivery pipe. Install hose on injector. Install Injector Checker (49 B092 953) on injector. (Scheme 65)
2. Install jumper between 2 terminals of fuel pump test circuit connector. See BASIC TESTING for test connector location. Turn ignition on. Connect injector checker to battery voltage. Note injector volume within 15 seconds.
3. Replace injectors which do not meet volume specifications. Check primary and secondary injectors in the same manner.

INJECTOR VOLUME SPECIFICATIONS

Scheme 65

Fuel Pump Relay Control

On 929 Models, see FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES section. On MPV see SELF-DIAGNOSTICS and WIRING DIAGRAMS.

BAC Valve

1. Ensure air flows through port A when valve is cold. (Scheme 66) If not, replace BAC valve.
2. Measure resistance of Idle Speed Control (ISC) valve at 2 wire connector of BAC valve. Resistance should be between 10.7-12.3 ohms, at normal operating temperature. If not, replace BAC valve.

Scheme 66

1. Operate engine to warm temperature. Ensure air temperature is above 113°F (45°C). Shut engine off. Connect voltmeter to pressure regulator control solenoid valve (Blue/Black wire on MPV and 929. (Scheme 67)
2. Start engine and note voltage. Voltage should be below 2 volts for 1-4 minutes after engine is started, then increase to approximately 12 volts after 1-4 minutes.

Scheme 67

Pressure Regulator Control Solenoid Valve

1. Disconnect hose from solenoid. Blow through port "A". see scheme 18 Air should flow from port "B". Remove connector from valve.
2. Apply battery voltage and ground to proper terminals. see scheme 18 Blow through port "A". Air should flow through air filter.

Intake Air Temperature Sensor

Using ohmmeter, measure sensor terminal resistance at specified temperature. See INTAKE AIR TEMPERATURE SENSOR RESISTANCE table. Replace sensor if not within specification.

INTAKE AIR TEMPERATURE SENSOR RESISTANCE

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING article.

KNOCK CONTROL

Note. If secondary (spark voltage) is available and no problems with knock control system are present, see TESTS W/CODES article. If no trouble codes are available or problem still exists, see PIN VOLTAGE CHART S and SENSOR RANGE CHARTS articles.

EMISSION SYSTEMS & SUB-SYSTEMS

Note. For complete vacuum schematics, see VACUUM DIAGRAMS article.

Air Pump

1. With engine at normal operating temperature, inspect all hose connections and belt tension.
2. Stop engine. Disconnect line from air pump to air control valve at the valve. Install Pressure Gauge Set (49 2113 010B) to the line. (Scheme 68) Connect tachometer to engine.
3. Start engine. Operate engine at idle and note pressure reading. Reading should exceed 1.7 psi (.12 kg/cm 2 ). Replace pump if not within specification.

Scheme 68

Converter Air Line Check Valve

Disconnect intake manifold-to-converter check valve hose at the check valve. Install tachometer and start engine. Accelerate engine to 1500 RPM. Check for exhaust leakage from check valve opening. Replace check valve if leakage exists.

Intake Manifold Check Valve

Disconnect air pump-to-air control valve air hose at the air pump. Install tachometer and start engine. Disconnect switching solenoid valve connector. Accelerate engine to 1500 RPM. Check for exhaust leakage at air control valve inlet fitting. (Scheme 69) Replace check valve if leakage exists.

Scheme 69

Scheme 70

Scheme 71

1. Operate engine to normal operating temperature. Stop engine and install tachometer. On turbo models equipped with Anti-Lock Brake Systems (ABS), disconnect and plug air hose and vacuum hose of air by-pass valve from the turbo. CAUTION: On turbo models with Anti-Lock Brake Systems (ABS), ensure air hose and vacuum hose of air by-pass valve are disconnected and plugged prior to removing air silencer-to-air control valve hoses.
2. On all models, disconnect air silencer-to-air control valve hose at air control valve. Place finger over air control valve outlet. Start engine and increase engine speed to 3750 RPM on turbo models or 1500-2500 RPM on non-turbo models. Note that air begins to flow at specified RPM.
3. Operate engine at idle. On turbo models, disconnect relief valve solenoid Blue connector. (Scheme 70) On non-turbo models, disconnect relief valve solenoid-to-air control valve hose. (Scheme 70)
4. Check that air flows from air control valve outlet above 1200 RPM on turbo models or at idle on non-turbo models. Reconnect vacuum hose or Blue connector.
5. Remove intake manifold-to-check valve hose. Disconnect hose at check valve on turbo models or intake manifold on non-turbo models. Place finger over opening.
6. On turbo models, disconnect hose at air control valve at air control valve. (Scheme 71) On non-turbo models, disconnect hose at switching solenoid valve. (Scheme 70)
7. With engine at idle, note that air flows from intake manifold fitting (non-turbo) or check valve (turbo). Replace air control valve if necessary. Reconnect all hoses.

Scheme 72

1. Install tachometer. Warm engine to normal operating temperature. Allow engine to idle. Connect Checker Light (49 F018 001) to Green connector. Check connector is located near air filter on non-turbo or intercooler on turbo. (Scheme 72)
2. Remove relief solenoid valve-to-air control valve hose at air control valve. Cover valve port with finger. Note that Green checker light activates and air flows at designated areas. See «GREEN CHECKER LIGHT OPERATIO»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) N table. NOTE: Checker light may occasionally turn off at approximately 1200 RPM. GREEN CHECKER LIGHT OPERATION Engine Condition Air Flow Light Operation Idle No On Above 3600 RPM Yes Off Deceleration No On
3. Remove right seat and floor mat. Disconnect heat hazard sensor connector. Install jumper wire to terminals of connector to the ECU. Ensure Green checker light does not activate and air flows from valve port at any engine speed. Remove jumper wire. Install connector at heat hazard sensor.
4. Start engine. Increase engine speed, noting that Green checker light does not activate and air flows from valve port when engine speed exceeds 1000-1200 RPM.

Switching Solenoid Valve Signal Check

1. Install tachometer. Warm engine to normal operating temperature. Allow engine to idle. Connect Checker Light (49 F018 001) to Green connector. (Scheme 72)
2. Disconnect hose at air control valve. (Scheme 71) Cover valve port with finger and note that Red checker light activates and air is drawn into valve at designated areas. See «RED CHECKER LIGHT OPERATION»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) table.

RED CHECKER LIGHT OPERATION

Split Air Solenoid Valve (M/T Models)

1. Connect voltmeter at Blue/Black wire terminal and ground of solenoid valve.
2. Turn ignition on. Place transmission in 5th gear and note voltage. Voltage should be below 2.5 volts in 5th gear and approximately 12 volts in all other gears.

Split Air Solenoid Valve (A/T Models)

1. Connect voltmeter at Blue/Black wire terminal and ground of solenoid valve.
2. Place gearshift in "D" range. Remove oil pressure switch connector on side of transmission. Install jumper wire between connector and ground. (Scheme 73)
3. Turn ignition on and note voltage. Voltage should be below 2.5 volts with jumper wire installed or approximately 12 volts with jumper wire removed.

Scheme 73

Port Air Solenoid Valve

1. Install voltmeter between Blue wire terminal and ground of solenoid valve. Start engine. Allow to idle and note voltage reading. Voltage should be below 2.5 volts.
2. Open throttle halfway and note voltage. Voltage should be approximately 12 volts.

Note. Solenoid valve voltage will be constantly below 2.5 volts once vehicle has operated over 20,000 miles.

Relief Solenoid Valve

1. Disconnect vacuum hoses from relief solenoid valve. Blow through port "B". (Scheme 74) Air should flow from air filter. Remove connector from solenoid valve.
2. Apply battery voltage and ground to proper terminals. (Scheme 74) Blow through port "B". Air should flow from port "A".

Scheme 74

Switching Solenoid Valve

1. Disconnect vacuum hoses from switching solenoid valve. Blow through port "A". see scheme 26 Air should flow from port "B". Remove connector from solenoid valve.
2. Apply battery voltage and ground to proper terminals. see scheme 26 Blow through port "A". Air should flow from air filter.

System Inspection (MPV 3.0L & 929)

1. No. 1 and No. 2 3-way solenoid valves are tested by removing vacuum hoses and blowing through port "B". With ignition off, air should flow out air filter.
2. Disconnect electrical connector and apply battery voltage to valve terminals. Blow air in port "B", air should exit at port "A".

Scheme 75

Scheme 76

Scheme 77

Scheme 78

1. For manual transmissions, disconnect neutral switch connector (M/T), jumper connector and start engine. For automatic transmissions, disconnect ECAT control unit after starting engine.
2. Connect voltmeter between Brown/Red solenoid wire and ground. With engine temperature less than 131°F (55°C), voltage should be 12 volts. With engine temperature greater than 131°F (55°C) and engine RPM less than 900, voltage should be 12 volts. With engine warm and engine RPM greater than 900, voltage should be less than 2.5 volts. (Scheme 78)
3. Disconnect vacuum hose from solenoid. Blow through port "B". Ensure air exhaust through air filter. (Scheme 79)
4. Disconnect 2-wire connector from solenoid. Connect 12 volts to one terminal and ground the other terminal of solenoid. Blow air through port "B". Ensure air exhaust through port "A".

Scheme 79

Scheme 80

1. Connect voltmeter between Blue/Yellow solenoid wire and ground. (Scheme 80) With engine temperature less than 158°F (70°C), start engine and note voltage. Voltage should be 12 volts.
2. Warm engine to normal operating temperature. With engine RPM less than 1500, voltage should be 12 volts. During acceleration with engine RPM greater than 1500, voltage should be less than 2.5 volts. Any time except acceleration, with engine RPM is greater than 1500, voltage should be 12 volts.
3. Disconnect vacuum hose from solenoid. Blow through port "B". Ensure air exhausts through air filter. (Scheme 79)
4. Disconnect 2 wire connector from solenoid. Connect 12 volts to one terminal and ground the other terminal of solenoid. Blow air though port "B". Ensure air exhausts through port "A". (Scheme 80)

Scheme 81

EGR SYSTEM TEST (929)

1. Check all connectors, hoses and routings for cracks, leakage, or restrictions and repair as needed. Bring engine to normal operating temperature and run at idle.
2. Increase engine speed to 2500 RPM. EGR valve should open. If not, test EGR position sensor, EGR duty solenoid valve and ECU circuits.

EGR CONTROL VALVE

Bring engine to normal operating temperature and run at idle. Disconnect and plug vacuum hose at EGR control valve. Engine should run smoothly. Connect vacuum pump to EGR control valve and apply more than 2.36 in. Hg. Engine should run rough or stop. If procedure fails, clean or replace EGR control valve.

Scheme 82

1. Backprobe EGR position sensor connector with voltmeter. (Scheme 82)
2. With EGR vacuum hose disconnected, connect vacuum pump. Turn ignition on and check voltages at connector. Use «EGR POSITION SENSOR VOLTAGE»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) table to compare results. EGR POSITION SENSOR VOLTAGE Terminal Voltage A 4.5-5.5 B Less Than 1.5 C Without Vacuum.25-.95 With Vacuum Approx. 4
3. If voltage is not correct at terminals A and B, check harness and connection at ECU connector terminals No. 2A and 2C. If voltage is not correct at terminal C, check sensor resistance, harness and ECU connector terminal No. 2F.
4. Check sensor resistance according to «EGR POSITION SENSOR RESISTANCE»(/mazda/mpv/v-1986-1991/remont/testing-diagnostics/#systemcomponent-tests-v6) table. If resistance is not within specifications, replace sensor.

EGR POSITION SENSOR RESISTANCE

929

1. Disconnect hoses and blow through vent hose. Ensure air flows. Disconnect solenoid connector. (Scheme 83)
2. Apply 12 volts to Violet/White wire connector of solenoid and ground both Red/Black wire connectors of solenoid. Blow through vacuum hose and ensure air does not flow. Replace solenoid if not okay.
3. Blow through vacuum hose and ensure air does not flow. Apply 12 volts to Yellow/Red wire connector of solenoid and ground both Red/Black wire connectors of solenoid. Blow through vacuum hose and ensure air does flow. Replace solenoid if not okay.

Scheme 83

DECELERATION CONTROL SYSTEM (MPV 3.0L & 929)

Deceleration control system is a function of ECU. It provides fuel cut during deceleration.

1. Using voltmeter, backprobe ECU connector terminals No. 3C, 3E or 3F. Start engine. Voltage should pulsate.
2. Increase engine speed to 4500 RPM. Suddenly decrease engine speed. Voltage should become constant during deceleration. If not, check idle switch, coolant temperature sensor, dashpot and all ECU connections.

See also:
• VARIABLE RESONANCE INDUCTION SYSTEM RPM VOLTAGES