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Engine Controls - System/component Tests - 3.4L: Other Toyota T100 I

Testing & Diagnostics 31 illustrations ~3350 words

Power & Ground Circuits

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

ModelLocation
T100Behind Passenger's Side Kick Panel

ECM LOCATION

Note. Fig. (Scheme 45) or (Scheme 46) identifies ECM terminals which are used for performing tests on various components in this article.

Scheme 45

Scheme 45

Scheme 46

Scheme 46

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 47)
  2. Using ohmmeter, measure resistance between specified terminals. See the «AIRFLOW METER RESISTANCE SPECIFICATIONS»(ref-21629-S28145194452001010300000) 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 48)
  4. Turn ignition on. Apply air into airflow meter and note voltage reading. (Scheme 48) While air is being applied, voltage reading should fluctuate. Replace airflow meter if voltage does not fluctuate. Remove voltmeter.

Scheme 47

Scheme 47

Scheme 48

Scheme 48
Application & TerminalsOhms
E2-THA
4°F (-20°C)10,000-20,000
32°F (0°C)4000-7000
68°F (20°C)2000-3000
104°F (40°C)900-1300
140°F (60°C)400-700
176°F (80°C)200-400

AIRFLOW METER RESISTANCE SPECIFICATIONS

CAMSHAFT POSITION SENSOR

For checking camshaft position sensor, see CAMSHAFT POSITION SENSOR under IGNITION CHECKS (DISTRIBUTORLESS IGNITION SYSTEM) in the BASIC TESTING - 3.4L article.

CRANKSHAFT POSITION SENSOR

For checking crankshaft position sensor, see CRANKSHAFT POSITION SENSOR under IGNITION CHECKS (DISTRIBUTORLESS IGNITION SYSTEM) in the BASIC TESTING - 3.4L article.

2WD 1/2 Ton

  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-21629-S32319915512001010300000) table. Replace EGR gas temperature sensor if resistance is not within specification.
Temperature °F (°C)K/ohms
122 (50)64-97
212 (100)11-16
302 (150)2-4

EGR GAS TEMPERATURE SENSOR SPECIFICATIONS

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

  1. Ensure ignition is off. Disconnect electrical connector from ECT sensor. See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION»(ref-21629-S23254010122001010300000) table. To verify wire colors for proper sensor identification, see wiring diagram in the WIRING DIAGRAMS article. NOTE: The ECT may be also identified using appropriate illustration in the «THEORY/OPERATION - 3.4L»(ref-21693) article.
  2. Using ohmmeter, check resistance between ECT sensor electrical terminals. Resistance should be within specification at designated temperature. (Scheme 49) Replace ECT sensor if resistance is not within specification.
ModelLocation
V6Behind Upper Timing Belt Cover, On Top Of Intake Manifold

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

Scheme 49

Scheme 49

KNOCK SENSOR

  1. Knock sensor(s) are located on the cylinder block. (Scheme 50) Remove knock sensor from cylinder block before testing. See the REMOVE/INSTALL/OVERHAUL article.
  2. Using ohmmeter, check that no continuity exists between electrical terminal of knock sensor and body of knock sensor. Replace knock sensor if continuity exists.

Scheme 50

Scheme 50

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 - 3.4L article for accessing diagnostic trouble codes.

A/T Models

  1. Disconnect electrical connector from park/neutral position switch, mounted on side of transmission or transaxle. Note terminal identification. (Scheme 51)
  2. Using ohmmeter, check for continuity at specified terminals with gearshift in proper positions. See the «PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS»(ref-21629-S36379296772001010300000) table. If proper continuity cannot obtained, adjust switch. Replace switch if proper continuity cannot be obtained.
Application & Gearshift PositionTerminal Continuity
Park5 & 6, 4 & 7
Reverse4 & 8
Neutral5 & 6, 4 & 10
Drive4 & 9
24 & 2
Low3 & 4

PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS

Scheme 51

Scheme 51

OXYGEN SENSOR HEATER

  1. A front oxygen sensor is used on exhaust pipe in front of catalytic converter and a rear oxygen sensor on exhaust pipe behind catalytic converter. Disconnect electrical connector from appropriate oxygen sensor and note oxygen sensor terminals. (Scheme 52)
  2. Using ohmmeter, measure resistance between oxygen sensor terminals +B and HT. (Scheme 52) Replace oxygen sensor if resistance is not within specs. See the «OXYGEN SENSOR HEATER RESISTANCE SPECIFICATIONS»(ref-21629-S08871438812001010300000) table.
ApplicationOhms @ 68°F (20°C)
Front Oxygen Sensor
A/T Models11-16
M/T Models5-7
Rear Oxygen Sensor11-16

OXYGEN SENSOR HEATER RESISTANCE SPECIFICATIONS

Scheme 52

Scheme 52

PICK-UP COILS

See PICK-UP COIL AIR GAP and PICK-UP COIL RESISTANCE under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM) in the BASIC TESTING - 3.4L article.

THROTTLE POSITION SENSOR

  1. Turn ignition off. Disconnect electrical connector from Throttle Position Sensor (TPS) on throttle body. Note terminal identification. (Scheme 53) NOTE: Some models require that vacuum be applied to throttle opener before checking TPS. See «TPS RESISTANCE SPECIFICATIONS»(ref-21629-S18631258132001010300000) table.
  2. Insert specified thickness feeler gauge between throttle stop screw and throttle lever and check resistance or continuity. See the «TPS RESISTANCE SPECIFICATIONS»(ref-21629-S18631258132001010300000) table. Replace or adjust TPS if not within specification.

Scheme 53

Scheme 53
Application TypeClearance In. (mm)Terminals TestedOhmmeter Reading
3.4L0 (0)VTA & E2280-6400
".013 (.32)IDL & E2500 Or Less
".021 (.53)IDL & E2No Continuity
"Fully OpenVTA & E22000-11,600
""VC & E22700-7700
(1) Apply vacuum to throttle opener before checking TPS.
(1)Apply vacuum to throttle opener before checking TPS.

TPS RESISTANCE SPECIFICATIONS (1)

VEHICLE SPEED SENSOR

  1. Vehicle speed sensor is located on rear of combination meter in instrument cluster. Connect ohmmeter between terminals "A" and "B". Terminals are located near vehicle speed sensor. (Scheme 54)or (Scheme 55).
  2. Rotate speedometer cable shaft and note reading. Ohmmeter should deflect from continuity to no continuity 4 times per speedometer cable shaft revolution. Replace speedometer if reading does not deflect as specified.

Scheme 54

Scheme 54

Scheme 55

Scheme 55

4WD SWITCH

  1. 4WD switch is located on passenger's side of transfer case. Remove switch from transfer case. Connect ohmmeter between switch terminals.
  2. Push pin on end of switch inward and ensure continuity exists. No continuity should exist when switch pin is released (outward) position. Replace switch if defective.

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-21629-S06164455782001010300000) table. NOTE: Circuit opening relay may also be identified using illustration in the «THEORY/OPERATION - 3.4L»(ref-21693) article or wire color. See wiring diagram in the WIRING DIAGRAMS article. CIRCUIT OPENING RELAY LOCATION Application Relay Location T100 Behind Glove Box, Near Passenger's Side Kick Panel
  2. Using ohmmeter, check continuity between specified terminals. (Scheme 56)
  3. Check circuit opening relay operation by applying battery voltage and ground and checking continuity between specified terminals. (Scheme 57) Replace circuit opening relay if defective.

Scheme 56

Scheme 56

Scheme 57

Scheme 57

EFI MAIN RELAY

  1. Ensure ignition is off. Remove EFI main relay. See «EFI MAIN RELAY LOCATION»(ref-21629-S00381816342001010300000) table. NOTE: The EFI main relay may also be identified using appropriate illustration in «THEORY/OPERATION - 3.4L»(ref-21693) article or wire color. See wiring diagram in the WIRING DIAGRAMS article. EFI MAIN RELAY LOCATION Application Location T100 Fuse/Relay Box Near Driver's Side Front Corner Of Engine Bay
  2. Using ohmmeter, check continuity between specified terminals. (Scheme 58)
  3. Check EFI main relay operation by applying battery voltage and ground and checking continuity between specified terminals. (Scheme 59) Replace EFI main relay if defective.

Scheme 58

Scheme 58

Scheme 59

Scheme 59

See CIRCUIT OPENING RELAY under RELAYS.

See EFI MAIN RELAY under RELAYS.

Fuel Pump Pressure

For fuel pump pressure testing, see FUEL PRESSURE in the BASIC TESTING - 3.4L 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-21629-S18097385352001010300000) table.
  2. To check fuel injector spray pattern and volume, remove fuel injector. See the REMOVE/INSTALL/OVERHAUL 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 60)and (Scheme 61).
  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 in the «BASIC TESTING - 3.4L»(ref-21583) 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 the «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-21629-S23255490772001010300000) table. NOTE: Ensure difference between fuel injector volume on all fuel injectors is within specification. See FUEL INJECTOR VOLUME SPECIFICATIONS table.
  7. Disconnect fuel injector tester. Ensure fuel leakage from end of fuel injector is one drop or less in specified time. See the «FUEL INJECTOR LEAKAGE SPECIFICATIONS»(ref-21629-S03901427262001010300000) table. Replace fuel injector if leakage exceeds specified amount.
ApplicationOhms @ 68°F (20°C)
3.4L13.8

FUEL INJECTOR RESISTANCE SPECIFICATIONS

ApplicationCu. In. (cc)
3.4L3.4-4.2 (56-69)
Maximum Difference Between Each Fuel Injector.4 (6)

FUEL INJECTOR VOLUME SPECIFICATIONS

ApplicationLeakage Time
T1001 Minute

FUEL INJECTOR LEAKAGE SPECIFICATIONS

Scheme 60

Scheme 60

Scheme 61

Scheme 61

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-21629-S41528881612001010300000) table. NOTE: Fuel pressure control VSV may also be identified using illustration in the «THEORY/OPERATION - 3.4L»(ref-21693) article or wire color. See wiring diagram in WIRING DIAGRAMS article. FUEL PRESSURE CONTROL VSV LOCATION Application Location 3.4L Near Rear Of Air Intake Chamber & Contains Brown 2-Pin Electrical Connector
  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-21629-S26055919702001010300000) 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 62) Replace fuel pressure control VSV if defective.
ApplicationOhms
T10033-39

FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS

Scheme 62

Scheme 62

Fuel Cut System

  1. When checking fuel cut system, engine RPM must be monitored.
  2. Scan tester is connected to data link connector No. 3 for monitoring engine RPM. For connecting of scan tester, see appropriate application under IDLE SPEED & MIXTURE in the «ADJUSTMENTS - 3.4L»(ref-21628) 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-21629-S24651489672001010300000) table. FUEL CUT SYSTEM TESTING SPECIFICATION Application Engine RPM 3.4L 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-21629-S23604617772001010300000) table. Shut engine off. Remove test equipment.
ApplicatioFuel Cut RPMFuel Return RPM
A/T(2)1200
M/T(2)1000
(1) Check with engine at operating temperature and A/C off. (2) Fuel cut specs. not available at time of publication.
(1)Check with engine at operating temperature and A/C off.
(2)Fuel cut specs. not available at time of publication.

FUEL CUT SYSTEM SPECIFICATIONS (1)

A/C IDLE-UP VALVE

  1. Remove A/C idle-up valve. See «A/C IDLE-UP VALVE LOCATIONS»(ref-21629-S40541108852001010300000) table. NOTE: The A/C idle-up valve may also be identified using illustration in the «THEORY/OPERATION - 3.4L»(ref-21693) article or wire color. See wiring diagram in the WIRING DIAGRAMS article. A/C IDLE-UP VALVE LOCATIONS Application Valve Location V6 Passenger's Side Front Corner Of Engine, 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-21629-S26405080062001010300000) table. A/C IDLE-UP VALVE RESISTANCE SPECIFICATIONS Application Ohms @ 68°F (20°C) T100 30-34
  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 63) Replace A/C idle-up valve if defective.

Scheme 63

Scheme 63

IDLE AIR CONTROL (IAC) VALVE

  1. Warm engine to normal operating temperature. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in «ADJUSTMENTS - 3.4L»(ref-21628) article.
  2. Apply parking brake and place transmission/transaxle in Neutral. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of data link connector No. 1. (Scheme 64) Start engine and note RPM. NOTE: Data link connector No. 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-21629-S24958673632001010300000) table. IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS Application Engine RPM 3.4L 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+ or +B and each remaining terminal. (Scheme 65)
  6. Replace IAC valve if resistance is not within specification. See «IAC VALVE RESISTANCE SPECIFICATIONS»(ref-21629-S24430016052001010300000) 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 66) 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 table. See wiring diagram in the WIRING DIAGRAMS article.
ApplicationOhms
Cold (1)17.0-24.5
Hot (2)21.5-28.5
(1) Cold is with temperature of 14-122°F (-10 - 50°C). (2) Hot is with temperature of 122-212°F (50-100°C).
(1)Cold is with temperature of 14-122°F (-10 - 50°C).
(2)Hot is with temperature of 122-212°F (50-100°C).

IAC VALVE RESISTANCE SPECIFICATIONS

Scheme 64

Scheme 64

Scheme 65

Scheme 65

Scheme 66

Scheme 66

IGNITION SYSTEM

Note. For basic ignition checks, see the BASIC TESTING - 3.4L article.

See KNOCK SENSOR under ENGINE SENSORS & SWITCHES.

2WD 1/2 Ton (Only)

  1. Ensure EGR vacuum modulator filter is clean and in good condition. Clean filter with compressed air (if necessary). NOTE: EGR vacuum modulator filter must be installed with coarse side facing upward, away from EGR vacuum modulator.
  2. Using "T" connector, install vacuum gauge in line with vacuum hose on top of EGR valve. Start engine. Ensure engine runs idles smoothly to ensure proper seating of EGR valve.
  3. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of data link connector No. 1 located in engine compartment. (Scheme 64) NOTE: The EGR system components can be checked with engine coolant temperature less than minimum temperature and engine at specified engine RPM.
  4. Operate engine with engine coolant temp. less than minimum temperature and at specified RPM. See the «EGR TESTING SPECIFICATIONS»(ref-21629-S30686670012001010300000) table. No vacuum reading should be obtained.
  5. Warm engine to normal operating temperature. Operate engine at specified engine RPM again. See «EGR TESTING SPECIFICATIONS»(ref-21629-S30686670012001010300000) table. Ensure a low vacuum reading is now obtained.
  6. Disconnect vacuum hose from port "R" of EGR vacuum modulator. (Scheme 67) Using additional hose, connect port "R" of EGR vacuum modulator directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See «EGR TESTING SPECIFICATIONS»(ref-21629-S30686670012001010300000) table. NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
  7. Remove vacuum hose, vacuum gauge and reconnect original vacuum hoses. To check EGR valve operation, remove and plug vacuum hose located on top of EGR valve.
  8. Using vacuum pump, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If EGR system does not operate as described, each individual component should be tested. Shut engine off. Remove jumper wire from data link connector No. 1.

Scheme 67

Scheme 67
ApplicationMinimum TemperatureEngine RPM
2WD 1/2 Ton Only113°F (45°C)(1) 2800
(1) Check at 3500 RPM when applying vacuum to port "R" on EGR vacuum modulator.
(1)Check at 3500 RPM when applying vacuum to port "R" on EGR vacuum modulator.

EGR TESTING SPECIFICATIONS

Scheme 68

Scheme 68

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 the ADJUSTMENTS - 3.4L article.

  1. Mark vacuum hose locations and disconnect vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" on EGR vacuum modulator. (Scheme 67) 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". (Scheme 67) 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-21629-S00742930952001010300000) table. Repeat test procedures in 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.
ApplicationEngine RPM
3.4L3500

EGR VACUUM MODULATOR TESTING SPECIFICATIONS

EGR VACUUM SWITCHING VALVE (VSV)

Note. When testing EGR VSV, use proper illustration to determine component location. (Scheme 68)

  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-21629-S13140675002001010300000) 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 69) Air pressure should flow from port "G". Connect battery voltage and ground to EGR VSV electrical terminals. (Scheme 69) Apply air pressure to port "E". Air pressure should flow through the air filter. Replace EGR VSV if defective.
ApplicationOhms @ 68°F (20°C)
2WD 1/2 Ton33-39

EGR VSV RESISTANCE SPECIFICATIONS

Scheme 69

Scheme 69

FUEL EVAPORATION SYSTEM

Note. Fuel evaporation systems contain different components depending on application. (Scheme 68) When testing fuel evaporation system components, use proper illustration to determine component location.

Charcoal Canister

  1. Disconnect hoses from charcoal canister. Check for clogged filter and/or stuck check valve by applying low air pressure to port "A". (Scheme 70) Ensure air flows freely from other ports on charcoal canister.
  2. Apply low air pressure to port "B". (Scheme 70) Ensure no air flows from port "A", but air flows freely from port "C". 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 70

Scheme 70

EVAP Vacuum Switching Valve

  1. Remove EVAP Vacuum Switching Valve (VSV). See EVAP VSV LOCATIONS table. (Scheme 68) EVAP VSV LOCATIONS Application Location T100 Near Charcoal Canister NOTE: EVAP VSV may also be identified by wire colors. See wiring diagram in the WIRING DIAGRAMS article.
  2. Using ohmmeter, ensure continuity exists between electrical terminals on EVAP VSV and resistance is within specification. See «EVAP VSV RESISTANCE SPECIFICATIONS»(ref-21629-S27245811602001010300000) table. EVAP VSV RESISTANCE SPECIFICATIONS Application Ohms @ 68°F (20°C) 3.4L 29-33
  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 71)
  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 72) Replace EVAP VSV if defective.

Scheme 71

Scheme 71

Scheme 72

Scheme 72

POSITIVE CRANKCASE VENTILATION (PCV)

  1. Remove 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.

M/T

  1. Warm engine to normal operating temperature. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in «ADJUSTMENTS - 3.4L»(ref-21628) article. Remove cap, filter and separator from dashpot. (Scheme 73)
  2. Start engine. Maintain engine speed at specified testing RPM. See «DASHPOT TESTING SPECIFICATIONS»(ref-21629-S33308424272001010300000) table. Plug Vacuum Transmitting Valve (VTV) hole with your finger. (Scheme 74)
  3. Release throttle. Dashpot should be extended and dashpot setting RPM should be as specified. See «DASHPOT TESTING SPECIFICATIONS»(ref-21629-S33308424272001010300000) table. If dashpot setting RPM is incorrect, rotate dashpot adjusting screw to obtain correct RPM. (Scheme 75)
  4. Repeat step 3) and ensure proper adjustment is obtained. To check Vacuum Transmitting Valve (VTV) operation, operate engine at dashpot testing RPM for a few seconds. Release throttle. Ensure engine returns to idle in approximately one second.
  5. Install separator, filter and cap. Ensure filter is installed with the coarse surface facing outward (away from dashpot).
ApplicationTesting RPMDashpot Setting RPM
V6 With M/T25001800-2200

DASHPOT TESTING SPECIFICATIONS

Scheme 73

Scheme 73

Scheme 74

Scheme 74

Scheme 75

Scheme 75

THROTTLE OPENER

  1. Warm engine to normal operating temperature. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in «ADJUSTMENTS - 3.4L»(ref-21628) 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-21629-S19470182772001010300000) 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.
Application(1) RPM
3.4L900-1950
(1) Check with engine at normal operating temp. and with electric cooling fan turned off (if equipped).
(1)Check with engine at normal operating temp. and with electric cooling fan turned off (if equipped).

THROTTLE OPENER SPECIFICATIONS