Engine Controls - System/component Tests: Other Toyota Avalon XX10

INTAKE AIR CONTROL VALVE SYSTEM

Note. Intake Air Control Valve (IACV) system may also be referred to as Acoustic Control Induction System (ACIS).

Scheme 5

Scheme 6

1. Using 3-way connector, connect vacuum gauge to actuator valve. (Scheme 5) Start engine. With engine idling, ensure no vacuum reading is obtained.
2. Fully open throttle and ensure vacuum reading momentarily reads about 8 in. Hg and actuator valve rod pulls inward. If actuator valve rod does not pull inward, proceed to next step.
3. Disconnect vacuum hose from actuator valve. Using vacuum pump, apply about 8 in. Hg of vacuum to actuator valve. Ensure actuator valve rod pulls inward and remains pulled inward for at least one minute. Replace actuator valve if defective. If actuator valve operates correctly, reconnect vacuum hose. Proceed to next step.
4. Disconnect hoses from vacuum tank, located near driver's side front corner of engine compartment, below battery tray. Apply air pressure to port "B" on vacuum tank. Ensure air passes out port "A". Perform STEP 1. (Scheme 6) Apply air pressure to port "A". Ensure air does not pass out port "B". Perform STEP 1. (Scheme 6)
5. Plug port "B" on vacuum tank. Using vacuum pump, apply about 8 in. Hg of vacuum to port "A". Perform STEP 2. (Scheme 6) Ensure vacuum reading will hold for at least one minute. Replace vacuum tank if defective and recheck system operation. If vacuum tank is okay, reconnect vacuum hoses. Proceed to next step.
6. Remove "V" bank cover, located on top of engine. (Scheme 7) Disconnect electrical connector and vacuum hoses from intake air control valve Vacuum Switching Valve (VSV), located near valve cover. (Scheme 7) NOTE: It may be necessary to remove emission control valve set which contains various vacuum switching valves for access to intake air control valve VSV.
7. Using ohmmeter, ensure continuity exists between electrical terminals on intake air control valve VSV and resistance is 33-39 ohms. Check that no continuity exists between each electrical terminal and the body of intake air control valve VSV.
8. Apply air pressure to port "B". Ensure air passes out the filter. Perform STEP 1. (Scheme 8) Connect battery voltage and ground to intake air control valve VSV terminals. Apply air pressure to port "B". Ensure air passes out port "A". Perform STEP 2. (Scheme 8) Replace intake air control valve VSV if defective. Recheck system operation.
9. If intake air control valve VSV is okay, reinstall VSV. Remove glove box for access to Engine Control Module (ECM). Turn ignition on.
10. Use voltmeter to check voltage between terminal No. 6 (Red/Yellow wire) of "E6" connector and chassis ground. (Scheme 9)
11. Voltage should be 9-14 volts. If voltage is not within specification, check for defective EFI main relay or wiring harness between EFI main relay and ECM. See «EFI MAIN RELAY»(ref-21595-S36559667432001010300000) under RELAYS. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article.
12. If EFI main relay and wiring harness are okay, check ECM ground circuit. If ECM ground circuit is okay, substitute another ECM and recheck system operation.

Scheme 7

Scheme 8

Power & Ground Circuits

For testing of power/ground circuits, see procedures in PIN VOLTAGE CHARTS article. See ECM LOCATION table for identifying ECM mounting locations.

ECM LOCATION

Note. (Scheme 9)identifies ECM terminals which are used for performing tests on various components in this article.

Scheme 9

AIRFLOW METER

Note. Airflow meter may be referred to as Volume Airflow (VAF) meter or Mass Airflow (MAF) meter.

1. Turn ignition off. Disconnect electrical connector from airflow meter. Note airflow meter terminal identification. (Scheme 10)
2. Using ohmmeter, measure resistance between specified terminals. See the «AIRFLOW METER RESISTANCE SPECIFICATIONS»(ref-21595-S27117766452001010300000) table. Replace airflow meter if resistance is not within specification.
3. To check airflow meter operation, ensure electrical connector is installed on airflow meter. Connect voltmeter leads to proper terminals on airflow meter with electrical connector installed. (Scheme 11)
4. Turn ignition on. Apply air into airflow meter and note voltage reading. (Scheme 11) While air is being applied, voltage reading should fluctuate. Replace airflow meter if voltage does not fluctuate. Remove voltmeter.

Scheme 10

Scheme 11

AIRFLOW METER RESISTANCE SPECIFICATIONS

CAMSHAFT POSITION SENSOR

For checking camshaft position sensor, see CAMSHAFT POSITION SENSOR under IGNITION CHECKS (DISTRIBUTORLESS IGNITION SYSTEM) in BASIC TESTING article.

CRANKSHAFT POSITION SENSOR

For checking crankshaft position sensor, see CRANKSHAFT POSITION SENSOR under IGNITION CHECKS (DISTRIBUTORLESS IGNITION SYSTEM) in BASIC TESTING article.

EGR GAS TEMPERATURE SENSOR

1. Remove EGR gas temperature sensor from side of EGR valve. Place threaded end of sensor and thermometer in container of oil.
2. Attach ohmmeter to electrical terminals. Heat oil and note resistance at specified temperature. See «EGR GAS TEMPERATURE SENSOR SPECIFICATIONS»(ref-21595-S03213779472001010300000) table. Replace EGR gas temperature sensor if resistance is not within specification.

EGR GAS TEMPERATURE SENSOR SPECIFICATIONS

ENGINE COOLANT TEMPERATURE SENSOR

1. Ensure ignition is off. Disconnect electrical connector from Engine Coolant Temperature (ECT) sensor. See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION»(ref-21595-S29602161142001010300000) table. To verify wire colors for proper sensor identification, see wiring diagram in «WIRING DIAGRAMS»(ref-21644) article. NOTE: The ECT may be also identified using appropriate illustration in «THEORY/OPERATION»(ref-21643) article.
2. Using ohmmeter, check resistance between ECT sensor electrical terminals. Resistance should be within specification at designated temperature. (Scheme 12) Replace ECT sensor if resistance is not within specification.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

Scheme 12

KNOCK SENSOR

1. Knock Sensors (KS) are located on the cylinder block. (Scheme 13) Remove KS from cylinder block before testing. See «REMOVE/INSTALL/OVERHAUL»(ref-22181) article.
2. Using ohmmeter, check that no continuity exists between electrical terminal of knock sensor and body of KS. Replace KS if continuity exists.

Scheme 13

PARK/NEUTRAL POSITION (PNP) SWITCH CIRCUIT

If problem exists with park/neutral position switch or circuit, a diagnostic trouble Code P1780 will be stored in the Engine Control Module (ECM). See the TESTS W/CODES article for accessing diagnostic trouble codes.

A/T Models

1. Disconnect electrical connector from Park/Neutral Position (PNP) switch, mounted on side of transmission or transaxle. Note terminal identification. (Scheme 14)
2. Using ohmmeter, check for continuity at specified terminals with gearshift in proper positions. See «PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS»(ref-21595-S21210251962001010300000) table. If proper continuity cannot obtained, adjust switch. Replace switch if proper continuity cannot be obtained.

PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS

Scheme 14

OXYGEN SENSOR HEATER

1. An oxygen sensor is used in each exhaust manifold and one on exhaust pipe behind catalytic converter. Disconnect electrical connector from appropriate oxygen sensor and note oxygen sensor terminals. (Scheme 16) NOTE: Electrical connector for oxygen sensor behind catalytic converter is located below passenger's side seat, beneath the carpet.
2. Using ohmmeter, measure resistance between oxygen sensor terminals "+B" and "HT". (Scheme 15)and (Scheme 16). Replace oxygen sensor if resistance is not within specification. See «OXYGEN SENSOR HEATER RESISTANCE SPECIFICATIONS»(ref-21595-S26874909292001010300000) table.

OXYGEN SENSOR HEATER RESISTANCE SPECIFICATIONS

Scheme 15

Scheme 16

THROTTLE POSITION SENSOR

1. Turn ignition off. Disconnect electrical connector from Throttle Position (TP) sensor on throttle body. Note terminal identification. (Scheme 17) NOTE: Some models require that vacuum be applied to throttle opener before checking (TP) sensor. See «TP SENSOR RESISTANCE SPECIFICATIONS»(ref-21595-S09508634922001010300000) table.
2. Insert specified thickness feeler gauge between throttle stop screw and throttle lever and check resistance or continuity. See the «TP SENSOR RESISTANCE SPECIFICATIONS»(ref-21595-S09508634922001010300000) table. Replace or adjust TP sensor if not within specification.

Scheme 17

TP SENSOR RESISTANCE SPECIFICATIONS

VEHICLE SPEED SENSOR

1. Vehicle Speed Sensor (VSS) is located on transmission/transaxle and contains a 3-wire connector. Connect voltmeter and battery voltage to vehicle speed sensor terminals. (Scheme 18)
2. While rotating vehicle speed sensor shaft, ensure voltage changes from zero to at least 11 volts. Voltage should change 4 times per revolution of the shaft. Replace vehicle speed sensor if voltage does not change as specified.

Scheme 18

FUEL PUMP ELECTRONIC CONTROL UNIT

See FUEL DELIVERY under FUEL SYSTEM.

CIRCUIT OPENING RELAY

1. Ensure ignition is off. Remove circuit opening relay. See «CIRCUIT OPENING RELAY LOCATION»(ref-21595-S42716844592001010300000) table. NOTE: Circuit opening relay may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21643) article or wire color. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article. CIRCUIT OPENING RELAY LOCATION Application Relay Location Avalon In Relay Box Behind Passenger's Side Kick Panel
2. Using ohmmeter, check continuity between specified terminals. (Scheme 19)
3. Check circuit opening relay operation by applying battery voltage and ground and checking continuity between specified terminals. (Scheme 20) Replace circuit opening relay if defective.

Scheme 19

Scheme 20

EFI MAIN RELAY

1. Ensure ignition is off. Remove EFI main relay. See «EFI MAIN RELAY LOCATION»(ref-21595-S18022253202001010300000) table. NOTE: The EFI main relay may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21643) article or wire color. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article. EFI MAIN RELAY LOCATION Application Location Avalon Fuse/Relay Box Near Driver's Side Front Corner Of Engine Compartment
2. Using ohmmeter, check continuity between specified terminals. (Scheme 21)
3. Check EFI main relay operation by applying battery voltage and ground and checking continuity between specified terminals. (Scheme 22) Replace EFI main relay if defective.

Scheme 21

Scheme 22

See CIRCUIT OPENING RELAY under RELAYS.

See EFI MAIN RELAY under RELAYS.

Fuel Pump Pressure

For fuel pump pressure testing, see FUEL PRESSURE under FUEL SYSTEM in BASIC TESTING article.

Fuel Injectors

1. Ensure ignition is off. Disconnect electrical connector at fuel injector. Using ohmmeter, measure resistance between fuel injector electrical terminals. Replace fuel injector if resistance is not within specification. See «FUEL INJECTOR RESISTANCE SPECIFICATIONS»(ref-21595-S18333776442001010300000) table.
2. To check fuel injector spray pattern and volume, remove fuel injector. See «REMOVE/INSTALL/OVERHAUL»(ref-22181) article. Disconnect fuel hose from fuel filter outlet. Use Delivery Hose (09268-41045) to install fuel injector between fuel filter and fuel pressure regulator. (Scheme 23)and (Scheme 24).
3. Place fuel injector into a clean graduated container. Place vinyl tube on end of fuel injector to prevent fuel spillage. NOTE: Scan tester is used to operate the fuel pump or by applying battery voltage to electric fuel pump.
4. Use scan tester to operate the fuel pump or apply battery voltage to electric fuel pump to pressurize the fuel system. See «FUEL PRESSURE»(ref-21707-S06191436482001010300000) under FUEL SYSTEM in BASIC TESTING article.
5. Connect fuel injector tester to fuel injector for 15 seconds. Use Fuel Injector Tester (09842-30070).
6. Measure fuel injector volume and check spray pattern. Test each fuel injector 2-3 times. Replace fuel injector if volume is not as specified. See «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-21595-S20900830352001010300000) table. NOTE: Ensure difference between fuel injector volume on all fuel injectors is within specification. See «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-21595-S20900830352001010300000) table.
7. Disconnect fuel injector tester. Ensure fuel leakage from end of fuel injector is one drop or less in specified time. See «FUEL INJECTOR LEAKAGE SPECIFICATIONS»(ref-21595-S01363241382001010300000) table. Replace fuel injector if leakage exceeds specified amount.

FUEL INJECTOR RESISTANCE SPECIFICATIONS

FUEL INJECTOR VOLUME SPECIFICATIONS

FUEL INJECTOR LEAKAGE SPECIFICATIONS

Scheme 23

Scheme 24

Note. Fuel pressure control system may also be referred to as fuel pressure-up system.

Fuel Pressure Control System

1. Fuel pressure control system uses a fuel pressure control Vacuum Switching Valve (VSV). Fuel pressure control VSV is supplied voltage through EFI main relay.
2. The Engine Control Module (ECM) will activate VSV by controlling ground circuit for approximately 90-180 seconds when restarting engine at normal operating temperature. Locate and remove fuel pressure control VSV. See «FUEL PRESSURE CONTROL VSV LOCATION»(ref-21595-S37796028882001010300000) table. NOTE: Fuel pressure control VSV may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21643) article or wire color. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article. FUEL PRESSURE CONTROL VSV LOCATION Application Location Avalon Rear VSV Below Cover On Intake Manifold, Near Pressure Regulator On Fuel Rail On Driver's Side
3. Using ohmmeter, check resistance and for continuity between fuel pressure control VSV electrical terminals. Replace fuel pressure control VSV if no continuity exists or resistance is not within specification. See «FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS»(ref-21595-S19664239022001010300000) table.
4. Ensure no continuity exists between each electrical terminal and fuel pressure control VSV body. Replace fuel pressure control VSV if continuity exists between electrical connector and fuel pressure control VSV body.
5. Check fuel pressure control VSV operation by applying air pressure to designated area and checking air passage, and then applying battery voltage and ground and retesting. (Scheme 25) Replace fuel pressure control VSV if defective.

FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS

Scheme 25

Fuel Cut System

1. When checking fuel cut system, engine RPM must be monitored.
2. Scan tester is connected to DLC-3 for monitoring engine RPM. For connecting of scan tester, see appropriate application under «IDLE SPEED & MIXTURE»(ref-21594-S08260220672001010300000) in ADJUSTMENTS article. CAUTION: Some tachometers may not be compatible with ignition system. Consult tachometer manufacturer before connecting tachometer to system. To avoid possible damage to ignitor and/or coil, DO NOT allow tachometer terminal to become grounded.
3. Start and warm engine to normal operating temperature. Ensure all accessories are off. Gradually increase engine RPM to maintain at least specified engine speed. See «FUEL CUT SYSTEM TESTING SPECIFICATION»(ref-21595-S13233940502001010300000) table. FUEL CUT SYSTEM TESTING SPECIFICATION Application Engine RPM Avalon 3500
4. Using stethoscope, check for fuel injector operating sound. Ensure when throttle lever is released, fuel injector stops operating momentarily (fuel cut RPM) and then resumes operating (fuel return RPM).
5. Ensure fuel cut RPM (if available) and fuel return RPM are within specification. See «FUEL CUT SYSTEM SPECIFICATIONS»(ref-21595-S02264235002001010300000) table. Shut engine off. Remove test equipment.

FUEL CUT SYSTEM SPECIFICATIONS (1)

A/C IDLE-UP SYSTEM

1. Before testing A/C idle-up system, ensure hoses at A/C idle-up valve are not damaged or clogged. A/C idle-up valve is located on end of air intake chamber, near throttle body. (Scheme 26)
2. Ensure idle speed is correct with engine at normal operating temperature. See «IDLE SPEED & MIXTURE»(ref-21594-S08260220672001010300000) in ADJUSTMENTS article. Apply parking brake. Place transaxle in Neutral.
3. With engine idling, turn A/C on. Install Jumper Wire (SST 09843-18020) between terminals "TE1" and "E1" on DLC-1. (Scheme 28)
4. Engine idle speed should increase for approximately 3 seconds and then drop to just slightly above normal idle speed and remain at this speed. If idle speed does not increase, proceed to step 6. If idle speed is correct, proceed to next step.
5. After about 15 seconds, ensure idle speed does not increase more than 100 RPM than idle speed obtained in step 4). If idle speed increases more than 100 RPM, rotate adjusting screw on A/C idle-up valve so idle speed does not exceed idle speed obtained in step 4). (Scheme 26) Remove jumper wire from DLC-1. Turn A/C off and remove tachometer.
6. If idle speed does not increase as specified, check A/C idle-up valve. See «A/C IDLE-UP VALVE»(ref-21595-S05984061972001010300000) under IDLE CONTROL SYSTEM. If the A/C idle-up valve operates correctly, proceed to next step).
7. Remove glove compartment for access to Engine Control Module (ECM). Turn ignition on.
8. Using voltmeter, check voltage between terminal No. 1 (White/Blue wire) of "E6" connector and chassis ground. (Scheme 9)
9. Voltage should be 9-14 volts with the ignition on and A/C off. If voltage is not within specification, check for defective EFI main relay or wiring harness between EFI main relay and ECM. See «EFI MAIN RELAY»(ref-21595-S36559667432001010300000) under RELAYS. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article.
10. If EFI main relay and wiring harness are okay, check ECM ground circuit. If ECM ground circuit is okay, substitute another ECM and recheck system operation.

Scheme 26

A/C IDLE-UP VALVE

1. Remove A/C idle-up valve. See «A/C IDLE-UP VALVE LOCATIONS»(ref-21595-S15896369292001010300000) table. NOTE: The A/C idle-up valve may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21643) article or wire color. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article. A/C IDLE-UP VALVE LOCATIONS Application Valve Location Avalon On Air Intake Chamber, Near Throttle Body & Contains 2-Pin Black Connector
2. Using ohmmeter, check resistance between A/C idle-up valve electrical terminals. Replace A/C idle-up valve if resistance is within specification. See «A/C IDLE-UP VALVE RESISTANCE SPECIFICATIONS»(ref-21595-S08468422422001010300000) table. A/C IDLE-UP VALVE RESISTANCE SPECIFICATIONS Application Ohms @ 68°F (20°C) Avalon 30-33
3. Ensure no continuity exists between each electrical terminal and body of A/C idle-up valve. To check A/C idle-up valve operation, apply air pressure to designated area and checking air passage, and then applying battery voltage and ground and retesting. (Scheme 27) Replace A/C idle-up valve if defective.

Scheme 27

IDLE AIR CONTROL (IAC) VALVE

1. Warm engine to normal operating temperature. Ensure idle speed is correct. See «IDLE SPEED & MIXTURE»(ref-21594-S08260220672001010300000) in ADJUSTMENTS article.
2. Apply parking brake and place transmission/transaxle in neutral. Install Jumper Wire (SST 09843-18020) between terminals "TE1" and "E1" of DLC-1. (Scheme 28) Start engine and note RPM. NOTE: DLC-1 is located in engine compartment.
3. Engine RPM should increase to specified RPM for 5 seconds, and then return to idle. See «IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS»(ref-21595-S20179360732001010300000) table. IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS Application Engine RPM Avalon 1000
4. If engine RPM is not as specified, check IAC valve resistance and operation. If engine RPM is within specification, remove jumper wire. Turn ignition off.
5. To check IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve located on lower area of throttle body. Using ohmmeter, measure resistance between terminal "+B" and each remaining terminal. (Scheme 29)
6. Replace IAC valve if resistance is not within specification. See «IAC VALVE RESISTANCE SPECIFICATIONS»(ref-21595-S39156783932001010300000) table.
7. To check IAC valve operation, remove IAC valve from throttle body. Connect battery voltage and ground to proper terminals and ensure valve opens and closes. (Scheme 30) Replace IAC valve if defective.
8. If IAC valve resistance is correct and operates correctly, check wiring circuit between Engine Control Module (ECM) and IAC valve. See «ECM LOCATION»(ref-21595-S40057037202001010300000) table. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article.

IAC VALVE RESISTANCE SPECIFICATIONS

Scheme 28

Scheme 29

Scheme 30

IGNITION SYSTEM

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

See KNOCK SENSOR under ENGINE SENSORS & SWITCHES.

EGR VACUUM MODULATOR

Note. When testing EGR vacuum modulator, it will be necessary to monitor engine RPM by using tachometer or scan tester depending on model application. For tachometer or scan tester connections, see IDLE SPEED & MIXTURE in ADJUSTMENTS article.

1. Mark vacuum hose locations and disconnect vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" on EGR vacuum modulator. see scheme 28 NOTE: Ports "P" and "R" are the double ports on side of EGR vacuum modulator. Port "Q" is single port on side of EGR vacuum modulator.
2. Apply air pressure to port "Q". see scheme 28 Air should pass freely through air filter side of EGR vacuum modulator.
3. Start and operate engine at specified RPM. See «EGR VACUUM MODULATOR TESTING SPECIFICATIONS»(ref-21595-S37801135132001010300000) table. Repeat steps 1 and 2. Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt. Reconnect vacuum hoses to proper locations.

EGR VACUUM MODULATOR TESTING SPECIFICATIONS

EGR VACUUM SWITCHING VALVE (VSV)

Note. When testing EGR VSV, use proper illustration to determine component location. see scheme 29or see scheme 30.

1. Disconnect electrical connector from EGR VSV. Using ohmmeter, check resistance between EGR VSV electrical terminals.
2. Replace EGR VSV if resistance is not within specification. See «EGR VSV RESISTANCE SPECIFICATIONS»(ref-21595-S01368375152001010300000) table. Ensure no continuity exists between each electrical terminal and EGR VSV body. Replace EGR VSV if continuity exists between any electrical terminal and VSV body.
3. Apply air pressure to port "E" without battery connected. (Scheme 31) Air pressure should flow from port "G". Connect battery voltage and ground to EGR VSV electrical terminals. (Scheme 31) Apply air pressure to port "E". Air pressure should flow through the air filter. Replace EGR VSV if defective.

EGR VSV RESISTANCE SPECIFICATIONS

Scheme 31

FUEL EVAPORATION SYSTEM

Note. Fuel evaporation systems contain different components depending on application. see scheme 29or see scheme 30. When testing fuel evaporation system components, use proper illustration to determine component location.

EVAP Thermal Vacuum Valve (Except California)

1. Drain cooling system. Remove EVAP Thermal Vacuum Valve (TVV), located in coolant passage. see scheme 30
2. Use cool water to cool threaded end of EVAP TVV to less than 104°F (40°C). Apply air pressure to top port on EVAP TVV. Ensure EVAP TVV is closed and no air will pass through lower port.
3. Heat water to greater than 138°F (59°C). Apply air pressure to top port on EVAP TVV. Ensure EVAP TVV is open and air passes through lower port. Replace EVAP TVV if defective. Apply thread sealant to threads of EVAP TVV and reinstall. Fill cooling system.

Charcoal Canister (California Only)

1. Disconnect hoses from charcoal canister. Check for clogged filter and/or stuck check valve by applying low air pressure to port "A" while holding port "B" closed. (Scheme 32) Ensure air flows freely from port "D".
2. Apply low air pressure to port "A" while holding ports "B" and "D" closed. (Scheme 32) Ensure no air flows from port "C".
3. Using vacuum pump, apply light vacuum to port "B". Ensure vacuum does not decrease when port "C" is closed, and that vacuum decreases with port "C" is opened.
4. While holding port "C" closed, use vacuum pump to apply light vacuum to port "A". Ensure air flows into port "B". Replace charcoal canister if defective.

Charcoal Canister (Except California)

1. Disconnect hoses from charcoal canister. Check for clogged filter and/or stuck check valve by applying low air pressure to port "A". (Scheme 33) Ensure air flows freely from other ports on charcoal canister.
2. Apply low air pressure to port "B". (Scheme 33) Ensure no air flows from any other ports on charcoal canister. Replace charcoal canister if defective.
3. To clean charcoal canister filter, apply 43 psi (3 kg/cm 2 ) air pressure to port "A" while holding port "B" closed. Ensure no activated carbon comes out of charcoal canister. DO NOT attempt to wash out charcoal canister.

Scheme 32

Scheme 33

EVAP Check Valve (Except California)

1. Remove EVAP check valve from lower hose on charcoal canister. Apply air pressure to Yellow colored side of EVAP check valve. Air should pass through EVAP check valve.
2. Apply air pressure to Black colored side of EVAP check valve. Air should not pass through EVAP check valve. Replace EVAP check valve if defective.

EVAP Vacuum Switching Valve (California)

1. Remove EVAP Vacuum Switching Valve (VSV). See «EVAP VSV LOCATIONS»(ref-21595-S40190732762004041500000) table. see scheme 29 EVAP VSV LOCATIONS Application Location California (1) On Emission Control Valve Set On Top Of Engine, Near Intake Manifold (1) EVAP VSV contains a Blue 2-pin electrical connector. NOTE: EVAP VSV may also be identified by wire colors. See wiring diagram in «WIRING DIAGRAMS»(ref-21644) article.
2. Using ohmmeter, ensure continuity exists between electrical terminals on EVAP VSV and resistance is within specification. See «EVAP VSV RESISTANCE SPECIFICATIONS»(ref-21595-S26008240232001010300000) table. EVAP VSV RESISTANCE SPECIFICATIONS Application Ohms @ 68°F (20°C) California 27-33
3. Ensure no continuity exists between each electrical terminal and the body of the EVAP VSV. Apply air pressure to port "E". Ensure no air passes out port "F". Perform STEP 1. (Scheme 34)
4. Connect battery voltage and ground to EVAP VSV electrical terminals. Apply air pressure to port "E". Ensure air passes out port "F". Perform STEP 2. (Scheme 35) Replace EVAP VSV if defective.

Scheme 34

Scheme 35

POSITIVE CRANKCASE VENTILATION

1. Remove Positive Crankcase Ventilation (PCV) valve. Attach hose to PCV valve. Blow air from cylinder head side of PCV valve. Ensure air passes easily through PCV valve.
2. Blow air from intake manifold side of PCV valve. Ensure air passes through PCV valve with some restriction. Replace PCV valve if valve does not function as described.

THROTTLE OPENER

1. Warm engine to normal operating temperature. Ensure idle speed is correct. See «IDLE SPEED & MIXTURE»(ref-21594-S08260220672001010300000) in ADJUSTMENTS article.
2. Disconnect/plug vacuum hose at throttle opener, located on side of throttle body. Start engine and note engine speed. Engine speed should be within specs. See «THROTTLE OPENER SPECIFICATIONS»(ref-21595-S23293013442001010300000) table.
3. If engine speed is not within specification, replace throttle body. Shut engine off. Reinstall vacuum hose on throttle opener. Start engine and ensure engine returns to proper idle speed.

THROTTLE OPENER SPECIFICATIONS