Engine Controls - System/component Tests: Other Lexus ES XV10 рестайлинг

CONNECTING TACHOMETER

Connect tachometer between chassis ground and terminal IG- of DLC No. 1. see scheme 17 See COMPONENT LOCATIONS.

ACIS SYSTEM CHECK

1. Connect vacuum gauge between IACV actuator and VSV. (Scheme 9) See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. Start engine. With engine idling, gauge needle should indicate no vacuum.
2. While snapping throttle fully open and releasing it, IACV actuator rod should move, and gauge needle should quickly fluctuate to the following specification: About 8 in. Hg or more.
3. System is okay if it operates as specified. If system does not operate as specified, perform ACIS CIRCUITS test.

Scheme 9

ACIS CIRCUIT

1. Check ACIS Vacuum Switching Valve (VSV). (Scheme 9) See AC IS VACUUM SWITCHING VALVE (VSV). If VSV is okay, remove glove box. Turn ignition on. Leave harness connectors attached to ECM. Backprobing connector, measure voltage between chassis ground and terminal No. 6 (Red/Yellow wire) of ECM connector E9. To identify ECM connectors and terminals (Scheme 10)
2. If battery voltage is not present, repair circuit between VSV and ECM. If battery voltage is present, check vacuum tank. See «ACIS VACUUM TANK»(ref-21745-S03768526072001010300000). If vacuum tank is okay, replace ECM.

Scheme 10

ACIS INTAKE AIR CONTROL VALVE (IACV)

Remove IACV assembly from end of air intake chamber. (Scheme 9) Apply about 8 in. Hg to IACV actuator. Replace IACV assembly if IACV actuator rod does not move, or if actuator does not hold vacuum for at least one minute.

ACIS VACUUM SWITCHING VALVE (VSV)

Disconnect vacuum hoses and electrical connector from VSV. (Scheme 9) Remove VSV if necessary. Replace VSV if it does not operate as follows.

1. Resistance across terminals is about 33-39 ohms.
2. Ensure no continuity exists between VSV case (ground) and each terminal of VSV connector (this checks for an internal short).
3. Blow through port "E". (Scheme 11) Air comes out of filter, but not out of port "F".
4. Apply battery voltage across terminals. Blow through port "E". Air comes out of port "F".

ACIS VACUUM TANK

Disconnect vacuum hoses from vacuum tank. (Scheme 9), (Scheme 10) and (Scheme 12). Replace vacuum tank if it does not operate as follows.

1. Blow through port "B". (Scheme 12) Air comes out of port "A".
2. Blow through port "A". Air does NOT come out of port "B".
3. Plug port "B". At port "A", apply 8 in. Hg. Vacuum holds for at least one minute.

Scheme 11

Scheme 12

ECM GROUND CIRCUITS

For ECM location, see COMPONENT LOCATIONS under INTRODUCTION. Measure resistance between engine (ground) and specified terminals of ECM connector. See ECM GROUND CIRCUITS table. If resistance is more than one ohm, repair ground circuit. If resistance is one ohm or less, ground circuit is okay (ECM may be faulty).

ECM GROUND CIRCUITS

ECM BACK-UP POWER CIRCUIT (BATTERY)

If circuit or components are faulty, a trouble code should set. See appropriate TESTS W/CODES - OBD-II article.

ECM POWER SOURCE CIRCUIT (IGNITION KEYED)

1. Ensure ECM ground circuits are okay. See «ECM GROUND CIRCUITS»(ref-21745-S13541745512001010300000). Remove glove box. Turn ignition on. Leave ECM connectors attached. See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. Backprobing connector, connect voltmeter negative lead to terminal No. 16 (Brown wire) of ECM connector E9 (this terminal is grounded). To identify ECM connectors and terminals (Scheme 10)
2. Connect voltmeter positive lead to terminals No. 23 (Black/Orange wire) of ECM connector E10. If battery voltage is present, ECM power circuit is okay. If battery voltage is not present, check EFI main relay. See «RELAYS»(ref-21745-S37949714652001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS.
3. If EFI main relay is okay, check EFI fuse. If EFI fuse is blown, check for short to ground in wiring. If EFI fuse is okay, check for open circuit between battery and EFI main relay, and between EFI main relay and ECM.
4. If circuits are okay, check IGN fuse. If IGN fuse is blown, check for short to ground in wiring. If IGN fuse is okay, check ignition switch. See STEERING COLUMN SWITCHES article in ACCESSORIES/SAFETY EQUIPMENT section. If ignition switch is okay, repair open circuit between ignition switch and EFI main relay, or between EFI main relay and ground.

CAMSHAFT SENSORS

Turn ignition off. Disconnect camshaft sensor connector. See COMPONENT LOCATIONS under INTRODUCTION. Measure resistance between terminals of camshaft sensor connector. Replace camshaft sensor if resistance is not as specified. See CAMSHAFT SENSOR RESISTANCE table.

CRANKSHAFT SENSOR

Turn ignition off. Disconnect crankshaft sensor connector. See COMPONENT LOCATIONS under INTRODUCTION. Measure resistance between terminals of crankshaft sensor connector. Replace crankshaft sensor if resistance is not as specified. See CRANKSHAFT SENSOR RESISTANCE table.

CRANKSHAFT SENSOR RESISTANCE

EGR TEMPERATURE SENSOR

Turn ignition off. Disconnect negative battery cable. Remove EGR temperature sensor. See COMPONENT LOCATIONS under INTRODUCTION. With sensing portion of EGR temperature sensor submerged in hot oil, measure resistance between terminals. Replace EGR temperature sensor if resistance is not as specified. See EGR TEMPERATURE SENSOR RESISTANCE table.

EGR TEMPERATURE SENSOR RESISTANCE

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Turn ignition off. Disconnect negative battery cable. Drain coolant. Remove ECT sensor. See COMPONENT LOCATIONS under INTRODUCTION. With sensing portion of ECT sensor submerged in water, measure resistance between terminals. Replace ECT sensor if resistance is not as specified. See ECT SENSOR RESISTANCE table.

ECT SENSOR RESISTANCE

INTAKE AIR TEMPERATURE (IAT) SENSOR

Note. IAT sensor is part of Mass Airflow (MAF) sensor.

IAT Sensor Resistance

Turn ignition off. Disconnect electrical connector from MAF sensor. See COMPONENT LOCATIONS under INTRODUCTION. Measure resistance between terminals THA and E2. (Scheme 13) Replace sensor if resistance is not as specified. See INTAKE AIR TEMPERATURE (IAT) SENSOR RESISTANCE table.

INTAKE AIR TEMPERATURE (IAT) SENSOR RESISTANCE

Scheme 13

KNOCK SENSOR

Remove knock sensor. See COMPONENT LOCATIONS under INTRODUCTION. Replace knock sensor if continuity exists between knock sensor connector terminal and knock sensor body (hex portion).

MASS AIRFLOW (MAF) SENSOR

Note. MAF sensor contains the intake air temperature sensor. See INTAKE AIR TEMPERATURE (IAT) SENSOR .

MAF Sensor Voltage

Leave MAF sensor connector attached. See COMPONENT LOCATIONS under INTRODUCTION. Turn ignition on. Backprobing connector, connect voltmeter positive lead to Red wire at MAF sensor connector. Connect voltmeter negative lead to Red/Black wire. If voltage does not fluctuate while blowing through MAF sensor, replace MAF sensor.

OXYGEN SENSOR HEATER RESISTANCE

Disconnect oxygen sensor connector. See COMPONENT LOCATIONS under INTRODUCTION. Measure resistance between terminals +B and HT of oxygen sensor connector. (Scheme 14) Replace oxygen sensor if resistance is not as specified. See OXYGEN SENSOR HEATER RESISTANCE table.

OXYGEN SENSOR HEATER RESISTANCE

Scheme 14

Main Sensors

If circuit or component is faulty, a trouble code should set. See appropriate TESTS W/CODES - OBD-II article.

Sub-Sensor

If circuit or component is faulty, a trouble code should set. See appropriate TESTS W/CODES - OBD-II article.

PARK/NEUTRAL POSITION (PNP) SWITCH

1. If PNP switch is out of adjustment, voltage signals may not be correctly applied to ECM, causing a trouble code to set. Before assuming PNP switch is faulty, adjust PNP switch. See «PARK/NEUTRAL POSITION (PNP) SWITCH»(ref-21745-S07413262952001010300000) under MISCELLANEOUS CONTROLS in appropriate «ADJUSTMENTS»(ref-21739) article.
2. After switch adjustment is completed, recheck for trouble code. If trouble code does not reset, PNP switch is okay. If trouble code resets, remove PNP switch. Check for continuity between specified terminals of PNP switch. See «PNP SWITCH CONTINUITY»(ref-21745-S33843106142001010300000) table. (Scheme 15) If continuity is not as specified, replace PNP switch. If continuity is as specified, install and adjust PNP switch.

PNP SWITCH CONTINUITY

Scheme 15

PARK/NEUTRAL POSITION (PNP) SWITCH CIRCUIT

If circuit or component is faulty, a trouble code should set. See appropriate TESTS W/CODES - OBD-II article.

SUB-THROTTLE POSITION (SUB-TP) SENSOR

Note. Vehicles with Traction Control System (TRAC) are equipped with a main TP sensor and a sub-TP sensor. The following procedure applies to sub-TP sensor. For main TP sensor, see THROTTLE POSITION (TP) SENSOR .

Disconnect sub-TP sensor connector. Measure resistance across specified terminals of sub-TP sensor connector. See SUB-TP SENSOR RESISTANCE table. (Scheme 16) If resistance is not as specified, adjust sub-TP sensor. See SUB-THROTTLE POSITION (SUB-TP) SENSOR in appropriate ADJUSTMENTS article. Recheck resistance. If resistance is still not as specified, replace sub-TP sensor.

SUB-TP SENSOR RESISTANCE

Scheme 16

THROTTLE POSITION (TP) SENSOR

Note. Vehicles with Traction Control System (TRAC) are equipped with a main TP sensor and a sub-TP sensor. The following procedure applies to main TP sensor. For sub-TP sensor, see SUB-THROTTLE POSITION (SUB-TP) SENSOR .

Disconnect TP sensor connector. Measure resistance across specified terminals of TP sensor connector. See TP SENSOR RESISTANCE table. (Scheme 16) If resistance is not as specified, adjust TP sensor. See THROTTLE POSITION (TP) SENSOR in ADJUSTMENTS article. Recheck resistance. If resistance is still not as specified, replace TP sensor.

TP SENSOR RESISTANCE

VEHICLE SPEED SENSOR (VSS) NO. 1

1. If speedometer operates, VSS No. 1 is okay. If speedometer does not operate, disconnect electrical connector from VSS No. 1. See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. Remove VSS No. 1. Connect battery positive lead to terminal No. 1 and negative lead to terminal No. 2. (Scheme 17)
2. While rotating gear, measure voltage between terminals No. 2 (negative lead) and No. 3 (positive lead). Replace VSS No. 1 if voltage does not alternate between zero and 12 volts, 4 times per revolution.

Scheme 17

VEHICLE SPEED SENSOR (VSS) NO. 1 CIRCUIT (SPEEDOMETER OPERATES)

1. Remove instrument cluster, but leave electrical connectors attached. Raise and support vehicle with one front wheel off of ground. Turn ignition on. Connect voltmeter between chassis ground and terminal No. 14 (Violet/Yellow wire) of instrument cluster top center 23-pin connector. Rotate front wheel.
2. If voltage alternates between zero and 5 or more volts for each revolution of wheel, go to next step. If voltage does not alternate between zero and 5 or more volts, replace character plate (speedometer assembly). Recheck voltage. If voltage is still incorrect, replace instrument cluster computer.
3. Check for open or shorted Violet/Yellow wire between instrument cluster and ECM. See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. If Violet/Yellow wire is okay, replace ECM.

VEHICLE SPEED SENSOR (VSS) NO. 1 CIRCUIT (SPEEDOMETER DOES NOT OPERATE)

1. If tachometer and fuel gauge operate, go to step 3). If tachometer and fuel gauge do not operate, disconnect instrument cluster top center 23-pin connector. Check for continuity between chassis ground and terminal No. 10 (Brown wire) of top center connector (harness side).
2. If continuity does not exist, repair Brown wire or ground connection. If continuity exists, replace instrument cluster computer, then recheck system.
3. If odometer and twin trip meter do not operate, go to next step. If odometer and twin trip meter operate, replace character plate (speedometer assembly). If speedometer still does not operate, replace instrument cluster computer.
4. Reconnect instrument cluster top center connector. At instrument cluster top center connector, connect voltmeter positive lead to terminal No. 13 (Green wire) and negative lead to terminal No. 15 (Green/Black wire). Shift transmission into Neutral. Raise and support vehicle with one front wheel off of ground. Turn ignition on. Rotate front wheel.
5. If voltage alternates between zero and 12 volts, replace instrument cluster computer. If voltage does not alternate between zero and 12 volts, check VSS No. 1. See «VEHICLE SPEED SENSOR (VSS) NO»(ref-21745-S27765221332001010300000) . 1. If VSS No. 1 is okay, repair circuit between VSS No. 1 and instrument cluster.

Ignitor

See SPARK TEST under IGNITION CHECKS in BASIC TESTING article.

Idle Air Control (IAC) Valve

See IDLE CONTROL SYSTEM .

Sub-Throttle Actuator Motor (Vehicles With Traction Control)

Disconnect electrical connector from sub-throttle actuator motor. (Scheme 18) Replace sub-throttle actuator motor if resistance across the following terminals is not 0.5-1.0 ohm.

1. ACM and "A".
2. ACM and "A-".
3. BCM and "B".
4. BCM and "B-".

Scheme 18

RELAYS

Note. For cooling fan relay testing, see SPECIFICATIONS & ELECTRIC COOLING FANS article in ENGINE COOLING section.

Preliminary Information

Remove relay. See COMPONENT LOCATIONS under INTRODUCTION. Determine which one of the following test procedures to perform. See RELAY CONNECTOR TYPE & TEST PROCEDURE NUMBER table. see scheme 11-15. Replace relay if it does not test as specified.

See ACOUSTIC CONTROL INDUCTION SYSTEM (ACIS) .

A/C Idle-Up Valve

See A/C IDLE-UP SYSTEM under MISCELLANEOUS CONTROLS.

EGR Vacuum Switching Valve (VSV)

See EXHAUST GAS RECIRCULATION (EGR) VACUUM SWITCHING VALVE (VSV) under EMISSION SYSTEMS & SUB-SYSTEMS.

EVAP (Charcoal) Canister Purge Vacuum Switching Valve (VSV)

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

Fuel Injectors

See FUEL SYSTEM .

Fuel Pressure Regulator Vacuum Switching Valve (VSV)

See FUEL PRESSURE REGULATOR VACUUM SWITCHING VALVE (VSV) under FUEL SYSTEM.

FUEL INJECTOR CIRCUIT

If circuit or component is faulty, a trouble code should set. See appropriate TESTS W/CODES - OBD-II article.

FUEL INJECTOR RESISTANCE

Turn ignition off. Disconnect injector connector. Measure resistance between injector terminals. If resistance is not about 13.8-14.2 ohms, replace injector.

FUEL INJECTOR VOLUME

1. Remove fuel injector. Connect Injection Measuring Tool Set (9268-41045). (Scheme 19) Attach a piece of vinyl tubing to bottom of fuel injector to prevent fuel splash. Put vinyl tubing into a graduated measuring cylinder.
2. Connect Jumper Wire (00843-18020) between terminals +B and FG of DLC No. 1. see scheme 17 Reconnect negative battery cable. Turn ignition on, engine off. Connect EFI Inspection Wiring (09842-30070) between fuel injector and a 12-volt battery for 15 seconds.
3. Compare measured volume with specified volume. See FUEL INJECTOR VOLUME (15 SECONDS) table. Replace injector if one or more of the following conditions exists: Volume is not within specification. Difference in volume between injectors exceeds specification. More than one drop leaks from injector within one minute of disconnecting EFI inspection wiring from battery.

FUEL INJECTOR VOLUME (15 SECONDS)

Scheme 19

FUEL PUMP RESISTANCE

Remove rear seat cushion and seat back. Disconnect 5-pin connector from fuel pump and sending unit assembly. Measure resistance between Blue/Black and White/Black wire terminals of 5-pin connector. Replace fuel pump if resistance is not 0.2-0.3 ohms at 68°F (20°C).

FUEL PUMP CONTROL CIRCUIT

1. Check fuel pump operation. See «FUEL PUMP OPERATION (USING DLC NO»(ref-21745-S28831605562001010300000). 1). If fuel pump operates, go to step 3). If fuel pump does not operate, check ECM keyed (ignition) power circuit. See «ECM POWER SOURCE CIRCUIT (IGNITION KEYED)»(ref-21745-S34463486122001010300000) under COMPUTERIZED ENGINE CONTROLS.
2. If circuit is okay, check fuel pump operation. See «FUEL PUMP OPERATION (USING FUEL PUMP CONNECTOR)»(ref-21745-S38969096022001010300000). If fuel pump operates, measure fuel pump resistance. See «FUEL PUMP RESISTANCE»(ref-21745-S10677533382001010300000). If fuel pump resistance is as specified, repair open circuit between fuel pump and terminal FP of DLC No. 1, or between fuel pump and chassis ground.
3. Check circuit opening relay. See «RELAYS»(ref-21745-S37949714652001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. If circuit opening relay is okay, remove glove compartment. Measure voltage between chassis ground and terminal No. 18 (Green/Red wire) of ECM connector E8. See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. To identify ECM connectors and terminals, see appropriate Fig. (Scheme 10).
4. If battery voltage is present, replace ECM. If battery voltage is not present, check for open circuit between EFI main relay and circuit opening relay, and between circuit opening relay and ECM.
5. If circuits are okay, remove circuit opening relay. While cranking engine, measure voltage between chassis ground and terminal No. 3 (Black/White wire) of socket where circuit opening relay was installed (corresponding terminal on relay is ST).
6. If battery voltage is present, repair open circuit between chassis ground and terminal No. 6 (White/Black wire) of socket where circuit opening relay was installed (corresponding terminal on relay is E1). If battery voltage is not present, remove glove box.
7. While cranking engine, measure voltage at terminal No. 13 (Black/White wire) of ECM connector E7. If 6 volts or more is present, repair open White/Black wire between chassis ground and terminal No. 6 of circuit opening relay. If ECM is receiving a starter signal, replace ECM.

FUEL PUMP PRESSURE

Note. See FUEL SYSTEM in BASIC TESTING article.

FUEL PRESSURE REGULATOR

Note. To check fuel pressure regulator, perform FUEL PRESSURE test under FUEL SYSTEM in BASIC TESTING article.

Disconnect electrical connector and vacuum hoses from fuel pressure regulator VSV. See COMPONENT LOCATIONS under INTRODUCTION. Replace VSV if it does not operate as follows

1. At 68°F (20°C), resistance across terminals should be 33-39 ohms.
2. There is no continuity between VSV case (ground) and each terminal of VSV connector (this checks for an internal short).
3. Blow through port "E". (Scheme 20) Air comes out of port "G".
4. Apply battery voltage across terminals. Blow air through port "E". Air comes out of filter.

Scheme 20

FUEL PRESSURE REGULATOR VSV CONTROL CIRCUIT

1. Check fuel pressure regulator VSV. See «FUEL PRESSURE REGULATOR VACUUM SWITCHING VALVE (VSV)»(ref-21745-S39778247082001010300000). If VSV is okay, remove glove box. Turn ignition on. Leave harness connectors attached to ECM. Measure voltage between chassis ground and terminal No. 25 (Black/Red wire) of ECM connector E7. To identify ECM connectors and terminals (Scheme 10)
2. If battery voltage is not present, repair circuit between EFI main relay and ECM. If battery voltage is present, check fuel pressure regulator by performing FUEL PRESSURE test under FUEL SYSTEM in «BASIC TESTING»(ref-21759) S article. If fuel pressure regulator is okay, replace ECM.

FUEL SYSTEM PRESSURE

Note. See FUEL SYSTEM in BASIC TESTING S article.

A/C IDLE-UP SYSTEM

See appropriate A/C IDLE-UP SYSTEM under MISCELLANEOUS CONTROLS.

IAC Valve Resistance

Disconnect IAC valve connector. See COMPONENT LOCATIONS under INTRODUCTION. At IAC valve connector, measure resistance between terminals +B and USC, and between terminals +B and RSO. see scheme 19 If resistance is not 19.3-22.3 ohms at 68°F (20°C), replace IAC valve. If resistance is as specified, reconnect IAC valve connector. Go to next procedure.

Air Assist System

1. Ensure engine is at normal operating temperature. Ensure idle speed is 650-750 RPM. See «CONNECTING TACHOMETER»(ref-21745-S03433444672001010300000) under INTRODUCTION. Shift transmission into Neutral. Turn A/C off. Connect Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1. see scheme 17 See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION.
2. Engine speed should increase to about 900-1300 RPM for about 10 seconds, then decrease to idle speed of 650-750 RPM. Stop engine. Disconnect air hose from air assist hose block. see scheme 20 Plug hose end, and cap off the hose fitting on the air assist hose block.
3. Start engine. If engine idles at about 500 RPM or less (or if engine stalls), air assist system is okay. If engine does not operate as specified, check for vacuum leak, then go to next procedure.

IGNITION SYSTEM

Note. For basic ignition checks, see IGNITION CHECKS in appropriate BASIC TESTING article.

DISTRIBUTOR SENSORS

ECM controls the ignition system based on signals from camshaft sensor and crankshaft sensor. See CAMSHAFT SENSORS and CRANKSHAFT SENSOR under ENGINE SENSORS & SWITCHES.

See BASIC TESTING article (ignitor is checked by performing SPARK TEST under IGNITION CHECKS).

(Primary Resistance)

Disconnect negative battery cable. Remove "V" bank cover from top of engine. Disconnect ignition coil electrical connector. See COMPONENT LOCATIONS under INTRODUCTION. Measure resistance between terminals of ignition coil electrical connector. If resistance is not as specified, replace ignition coil. See IGNITION COIL RESISTANCE table.

(Secondary Resistance)

Information is not available from manufacturer.

IGNITION COIL RESISTANCE - Ohms

EXHAUST GAS RECIRCULATION (EGR) SYSTEM

Note. DO NOT warm the engine until specified. Some testing must be performed when engine is cold.

1. Remove cap and filter from top of EGR vacuum modulator. (Scheme 21) See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. Clean filter with compressed air. Install filter with coarse side facing upward. Install cap.
2. Using a vacuum "T", connect a vacuum gauge in hose between EGR valve and Vacuum Switching Valve (VSV). To ensure EGR valve is seating, start engine and check idle quality.
3. If idle is smooth, go to next step. If idle is rough, disconnect vacuum hose from EGR valve. If idle is smooth, check for problems in EGR vacuum control system. If idle is still rough, EGR valve is not seating. Replace EGR valve.
4. Ensure engine coolant is less than 131°F (55°C). Connect Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1. see scheme 17 Run engine at 2800 RPM. See «CONNECTING TACHOMETER»(ref-21745-S03433444672001010300000) under INTRODUCTION. There should be no vacuum indicated (no EGR occurs). If any vacuum is indicated, check EGR system components. If no vacuum is indicated, warm engine to 176°F (80°C). Check vacuum with engine running at 2800 RPM.
5. If no vacuum or high vacuum is indicated, check EGR system components. If low vacuum (partial EGR) is indicated, disconnect vacuum hose from port "R" of EGR vacuum modulator. (Scheme 21) Connect a separate hose between port "R" and intake manifold.
6. With engine running at 3500 RPM, high vacuum should be indicated (as volume of recirculated exhaust gas increases, engine will start to misfire). If no vacuum or low vacuum is indicated, check EGR system components. If high vacuum is indicated, disconnect jumper wire from DLC No. 1.
7. Disconnect vacuum gauge. Reconnect all vacuum hoses. Disconnect vacuum hose from EGR valve. Apply vacuum directly to EGR valve. If engine runs rough or stalls, system is okay. If engine does not run rough or stall, replace EGR valve.

Scheme 21

EXHAUST GAS RECIRCULATION (EGR) VACUUM MODULATOR

Turn engine off. Label and disconnect all vacuum hoses from EGR vacuum modulator. See COMPONENT LOCATIONS under INTRODUCTION. Replace EGR vacuum modulator if it does not operate as follows

1. Block ports "P" and "R" with finger. (Scheme 21) Blow through port "Q". Air flows freely out of filter.
2. Start and run engine at 3500 RPM. See «CONNECTING TACHOMETER»(ref-21745-S03433444672001010300000) under INTRODUCTION. Block ports "P" and "R" with finger. Blow through port "Q". There is strong resistance to airflow out of filter.

EXHAUST GAS RECIRCULATION (EGR) VACUUM SWITCHING VALVE (VSV)

Disconnect vacuum hoses and electrical connector from VSV. See COMPONENT LOCATIONS under INTRODUCTION. Replace VSV if it does not operate as follows.

1. Resistance across terminals of VSV should be 33-39 ohms at 68°F (20°C).
2. There is no continuity between VSV case (ground) and each terminal of VSV connector (this checks for an internal short).
3. Blow through port "E". see scheme 22 Air comes out of port "G".
4. Apply battery voltage across terminals. Blow through port "E". Air comes out of filter.

EXHAUST GAS RECIRCULATION (EGR) VALVE

Start engine and allow it to idle. Disconnect and plug vacuum hose to EGR valve. Connect a vacuum pump to EGR valve. Apply vacuum. If engine idles rough or stalls, EGR valve is functioning properly. If engine does not idle rough or stall, check for plugged EGR port or defective EGR valve. Repair as necessary.

EVAP Canister (With Calif. Emissions)

Visually inspect EVAP canister and hoses for cracks and damage. Disconnect all hoses from canister. Replace EVAP canister if it does not function as follows

1. Hold port "B" closed and blow air into port "A" on top of canister. (Scheme 22) Air should flow from port "D".
2. Plug port "B" and "D" and blow air into port "A". Air should not flow from port "C".
3. Connect a vacuum pump to port "B". Apply 0.29 in. Hg. With port "C" plugged, vacuum should hold. With port "C" unplugged, vacuum should release.
4. Connect vacuum pump to port "A" and plug port "C". Apply 0.29 Hg. Air should flow into port "B".

Scheme 22

EVAP Thermal Valve (With Federal Emissions)

1. Drain coolant. Remove thermal valve. See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. Cool thermal valve to less than 104°F (40°C). Blow air into upper vacuum port. Air should NOT flow out of lower port.
2. Heat thermal valve in water to greater than 138°F (59°C). Blow air into upper port. Air should flow from lower port. If air does not flow as specified, replace thermal valve.

Check Valve For EVAP Canister (With Federal Emissions)

Remove check valve. See COMPONENT LOCATIONS under INTRODUCTION. Air should flow from Yellow port to Black port. Air should not flow from Black port to Yellow port. Replace check valve if it does not operate as specified. Install check valve with Black port toward canister.

PCV Valve

Remove PCV valve. See COMPONENT LOCATIONS under INTRODUCTION. Inspect PCV hoses, connections and gaskets for leaks and damage. Blow air through cylinder head side of PCV valve. Air should pass freely through PCV valve. Blow air through intake manifold side of PCV valve. Air should pass freely through PCV valve. Clean or replace PCV valve if air does not flow as specified.

THROTTLE OPENER

Run engine at operating temperature. Ensure idle speed is 650-750 RPM. See CONNECTING TACHOMETER under INTRODUCTION. Disconnect vacuum hose from throttle opener, and plug hose end. Run engine at 2500 RPM, then release throttle. Compare actual engine speed with specified engine speed. See THROTTLE OPENER SET SPEED SPECIFICATIONS table. If engine speed is not as specified

1. Replace throttle body.

THROTTLE OPENER SET SPEED SPECIFICATIONS

MISCELLANEOUS CONTROLS

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

A/C CUT CONTROL SYSTEM

1. Remove glove box. Turn ignition on. Leave harness connectors attached to ECM. See «COMPONENT LOCATIONS»(ref-21745-S16233931862001010300000) under INTRODUCTION. Measure voltage between chassis ground and terminal No. 5 (Light Green/Red wire) of ECM connector E10. To identify ECM connectors and terminals (Scheme 10) Wit h A/C on, battery voltage should be present. With A/C off, 0-2 volts should be present.
2. If voltage is as specified, replace A/C control assembly. If voltage is not as specified, check for open or short in circuit between ECM and A/C control assembly. If circuit is okay, replace A/C control assembly.

Voltage At ECM

Remove glove box. Leave ECM connectors attached. See COMPONENT LOCATIONS under INTRODUCTION. Turn ignition on, engine off. Measure voltage between chassis ground and terminal No. 1 (White/Blue wire) of ECM connector E9. To identify ECM connectors and terminals (Scheme 10) If battery voltage is not pre sent, repair White/Blue wire between EFI main relay and terminal No. 1 of ECM connector E9.

Turn ignition off. Disconnect negative battery cable. Disconnect electrical connector and hoses from A/C idle-up valve. See COMPONENT LOCATIONS under INTRODUCTION. (Scheme 23) Remove A/C idle-up valve. Replace A/C idle-up valve if it does not operate as follows.

1. Resistance across terminals is 30-33 ohms at 68°F (20°C).
2. There is no continuity between VSV case (ground) each terminal of VSV (this checks for an internal short).
3. Blow through port "E". (Scheme 23) Air does NOT come out of port "F".
4. Apply battery voltage across terminals. Blow through port "E". Air comes out of port "F".

Scheme 23

COOLING FAN SYSTEM

Note. Use the following procedure to check operation of cooling fan system. For all other cooling fan testing, see the ENGINE COOLING FAN article in ENGINE COOLING in section.

Cooling fan is driven by a hydraulic motor that receives pressure from the power steering pump. See ENGINE COOLING FAN article in ENGINE COOLING section.

TRANSMISSION

Note. For transmission diagnostic information, see the TRANSMISSION SERVICING article.