Engine Controls - System/component Tests: Other Lexus ES XV20

Intake Air Control Valve (ES300, GS300 & SC300)

1. Install a 3-way vacuum "T" fitting in vacuum hose between Intake Air Control Valve (IACV) actuator and ACIS Vacuum Switch Valve (VSV). see scheme 1-6. Connect a vacuum gauge to vacuum "T" fitting. Start engine. With engine idling, ensure vacuum is not present.
2. Snap accelerator to wide open throttle (WOT). On ES300, ensure vacuum reading momentarily reads about 7.9 in. Hg and IACV actuator rod pulls out. (Scheme 18) On GS300 and SC300, ensure vacuum reading momentarily reads about 9.8 in. Hg. and IACV actuator rod pulls down. On all models, if vacuum is not as specified or actuator valve rod fails to pull out (ES300) or down (GS300 and SC300), go to next step.
3. Remove IACV. Apply about 7.9 in. Hg (ES300), 15.8 in. Hg (GS300 and SC300) to IACV actuator. On ES300, if IACV actuator rod does not move, replace IACV actuator. On GS300 and SC300, if IACV actuator rod does not move, turn adjusting screw on IACV assembly.
4. If IACV actuator rod still does not move, replace IACV actuator. On all models, if IACV actuator rod moves, check to see if diaphragm holds vacuum for at least one minute. If diaphragm does not hold vacuum, replace actuator. If diaphragm holds vacuum, go to next procedure.

Scheme 18

Intake Air Control Valve (GS400 & SC400)

1. Remove throttle body. See THROTTLE BODY in REMOVE/INSTALL/OVERHAUL article. Remove upper and lower intake manifolds. See INTAKE MANIFOLD in REMOVE/INSTALL/OVERHAUL article. Install a 3-way vacuum "T" fitting in vacuum hose between Intake Air Control Valve (IACV) actuator and ACIS Vacuum Switch Valve (VSV). see scheme 1-6. Reinstall intake manifold and throttle body.
2. Connect a vacuum gauge to vacuum "T" fitting. Start engine. With engine idling, ensure vacuum reading is about 11.8 in. Hg, and IACV actuator rod is pulled out. (Scheme 18) If vacuum is not as specified or actuator valve rod fails to pull out, go to next step.
3. Snap accelerator to wide open throttle (WOT) position. Vacuum should not exist during wide open throttle and IACV actuator rod should not be pulled out.
4. Remove IACV. Apply about 11.8 in. Hg to IACV actuator. If IACV actuator rod does not move, replace IACV actuator. If IACV actuator rod moves, check to see if diaphragm holds vacuum for at least one minute. If diaphragm does not hold vacuum, replace actuator. If diaphragm holds vacuum, go to next procedure.

Intake Air Control Valve (LS400)

1. Remove engine cover. Remove battery cover, air cleaner and intake air hose. Remove throttle body. See THROTTLE BODY in REMOVE/INSTALL/OVERHAUL article. Remove intake manifold. See INTAKE MANIFOLD in REMOVE/INSTALL/OVERHAUL article. Install a 3-way vacuum "T" fitting in vacuum hose between Intake Air Control Valve (IACV) actuator and ACIS Vacuum Switch Valve (VSV). see scheme 1-6. Reinstall intake manifold and throttle body.
2. Connect a vacuum gauge to vacuum "T" fitting. Start engine. With engine idling, ensure vacuum reading is about 11.8 in. Hg, and IACV actuator rod is pulled out. (Scheme 18) If vacuum is not as specified or actuator valve rod fails to pull out, go to next step.
3. Snap accelerator to wide open throttle (WOT) position. Vacuum should not exist during wide open throttle and IACV actuator rod should not be pulled out.
4. Remove IACV. Apply about 11.8 in. Hg to IACV actuator. If IACV actuator rod does not move, replace IACV actuator. If IACV actuator rod moves, check to see if diaphragm holds vacuum for at least one minute. If diaphragm does not hold vacuum, replace actuator. If diaphragm holds vacuum, go to next procedure.

ACIS Vacuum Tank (ES300, GS300 & SC300)

1. Disconnect vacuum hoses from vacuum tank. On ES300, vacuum tank is located at left side member, under battery tray. On GS300 and SC300, vacuum tank is located under air intake chamber. see scheme 1-6.
2. On ES300, apply compressed air to port "B". (Scheme 19) Air should flow out of port "A". Apply compressed air to port "A". Air should not flow from port "B". Plug port "B". Apply 7.9 in. Hg to port "A". Vacuum should hold for at least one minute.
3. On GS300 and SC300, apply compressed air to port "A". (Scheme 19) Air should flow out of port "B". Apply compressed air to port "B". Air should not flow from port "A". Plug port "B". Apply 15.8 in. Hg to port "A". Vacuum should hold for at least one minute.
4. On all models, if ACIS vacuum tank does not operate as specified, replace ACIS vacuum tank. If ACIS vacuum tank operates as specified, go to next procedure.

Scheme 19

ACIS Vacuum Tank (GS400, LS400 & SC400)

Disconnect vacuum hoses from vacuum tank. Vacuum tank is located under front of intake manifold. see scheme 1-6. Apply compressed air to port "A". (Scheme 19) Air should flow out of port "B". Apply compressed air to port "B". Air should not flow out of port "A". Plug port "B". Apply 11.8 in. Hg to port "A". Vacuum should hold for at least one minute. If ACIS vacuum tank does not operate as specified, replace ACIS vacuum tank. If ACIS vacuum tank operates as specified, go to next procedure.

ACIS Vacuum Switching Valve (ES300, GS300 & SC300)

1. On GS300 and SC300, remove engine wire clamp from dipstick if equipped. Remove bolt and A/T fluid dipstick and guide. Remove and discard "O" ring. On ES300, remove engine cover and wire harness cover. On all models, remove emission control valve set. Disconnect vacuum hoses and electrical connector from Vacuum Switching Valve (VSV). see scheme 1-6.
2. Remove VSV if necessary. Measure resistance between VSV terminals. On ES300, if resistance is 33-39 ohms at 68°F (20°C), go to next step. On GS300 and SC300, if resistance is 39-45 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace ACIS VSV.
3. Check for continuity between VSV case and each terminal at VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
4. Apply compressed air to port "E". (Scheme 20) Air should flow out of filter, but not out of port "F". Apply 9-14 volts and ground to VSV terminals. Apply compressed air to port "E". Air should flow out of port "F", but not out of filter. If ACIS VSV does not function as specified, replace ACIS VSV.

Scheme 20

ACIS Vacuum Switching Valve (GS400 & SC400)

1. Remove engine cover. Remove air cleaner inlet tube. Disconnect throttle body. See THROTTLE BODY in REMOVE/INSTALL/OVERHAUL article. Remove intake manifold assembly. See INTAKE MANIFOLD ASSEMBLY in REMOVE/INSTALL/OVERHAUL article. Disconnect vacuum hoses and electrical connector from Vacuum Switching Valve (VSV). see scheme 1-6. Remove VSV. Measure resistance between VSV terminals. If resistance is 33-39 ohms, go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal at VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Apply air through port "E". (Scheme 20) Air should flow out of filter, but not out of port "F". Apply 9-14 volts and ground to VSV terminals. Apply compressed air to port "E". Air should flow out of port "F". If ACIS VSV does not function as specified, replace ACIS VSV.

ACIS Vacuum Switching Valve (LS400)

1. Remove engine cover. Remove battery cover and air cleaner inlet tube. Disconnect throttle body. See THROTTLE BODY in REMOVE/INSTALL/OVERHAUL article. Remove intake manifold assembly. See INTAKE MANIFOLD ASSEMBLY in REMOVE/INSTALL/OVERHAUL article. Remove vacuum tank. Disconnect vacuum hoses and electrical connector from Vacuum Switching Valve (VSV). see scheme 1-6. Remove VSV if necessary. Measure resistance between VSV terminals. If resistance is 33-39 ohms, go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal at VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Apply air through port "E". (Scheme 20) Air should flow out of filter, but not out of port "F". Apply 9-14 volts and ground to VSV terminals. Apply compressed air to port "E". Air should flow out of port "F". If ACIS VSV does not function as specified, replace ACIS VSV.

ECM BACK-UP POWER CIRCUIT (BATTERY)

If circuit or components are faulty, a Diagnostic Trouble Code (DTC) should set. See TESTS W/CODES article.

ECM POWER SOURCE CIRCUIT (IGNITION KEYED)

ES300

1. Access ECM behind glove box. Turn ignition on. Leave ECM connectors attached. Backprobing connector, connect voltmeter negative lead to terminal E1 and positive lead to terminal "B" at ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10. If 9-14 volts is present, ECM power circuit is okay. Diagnose by symptom. See TESTS W/O CODES article. If 9-14 volts is not present, go to next step.
2. Check for an open circuit in wiring harness between ground and terminal E1 at ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
3. Measure voltage between chassis ground and terminal IGSW at ECM connector. If 9-14 volts is present, go to step 5). If 9-14 volts is not present, check the IGN fuse in instrument panel junction block at lower left finish panel.
4. If fuse is blown, repair cause of blown fuse. If fuse is okay, check ignition switch. See STEERING COLUMN SWITCHES article. Replace ignition switch as necessary and retest. If ignition switch is okay, repair open circuit between battery and ignition switch, or between ignition switch and ECM.
5. Turn ignition on. Measure voltage between chassis ground and terminal MREL at ECM connector. If 9-14 volts is not present, replace ECM. If 9-14 volts is present, check EFI fuse located in engine compartment fuse/relay block, at left front of engine compartment, in front of strut tower. If EFI fuse is blown, repair cause of blown fuse.
6. If fuse is okay, check EFI main relay located in engine compartment fuse/relay block, at left front of engine compartment, in front of strut tower. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay is okay, check circuit between chassis ground and terminal M-REL at ECM connector. If circuit is okay, repair circuit between battery and EFI fuse.

GS300 & GS400

1. Access ECM behind glove box. Turn ignition on. Connect voltmeter negative lead to terminal E1 and positive lead to terminal "B". See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10. If 9-14 volts is present, ECM keyed (ignition) power circuit is okay. Diagnose by symptom. See TESTS W/O CODES article. If 9-14 volts is not present, go to next step.
2. Check for an open circuit in wiring harness between ground and terminal E1 of ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
3. Measure voltage between chassis ground and terminal IGSW at ECM connector. If 9-14 volts is present, go to step 5). If 9-14 volts is not present, check the IGN fuse in driver side junction block behind left kick panel.
4. If fuse is blown, repair cause of blown fuse. If fuse is okay, check ignition switch. See STEERING COLUMN SWITCHES article. Replace ignition switch as necessary and retest. If ignition switch is okay, repair open circuit between battery and ignition switch, or between ignition switch and ECM.
5. Turn ignition on. Measure voltage between chassis ground and terminal M-REL at ECM connector. If 9-14 volts is not present, replace ECM. If 9-14 volts is present, check EFI fuse located in engine compartment fuse/relay block, at right rear or engine compartment, behind strut tower. If EFI fuse is blown, repair cause of blown fuse.
6. If fuse is okay, check EFI main relay located in engine compartment fuse/relay block, at right rear or engine compartment, behind strut tower. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay is okay, check circuit between chassis ground and terminal M-REL at ECM connector. If circuit is okay, repair circuit between battery and EFI fuse.

LS400

1. Access ECM behind glove box. Leave electrical connectors attached to ECM. Turn ignition on. Backprobing connector, connect voltmeter negative lead to terminal E1 and positive lead to terminal "B" at ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10.
2. If 9-14 volts is present, ECM keyed (ignition) power circuit is okay. Diagnose by symptom. See TESTS W/O CODES article. If 9-14 volts is not present, go to next step.
3. Check for an open circuit in wiring harness between ground and terminal E1 at ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
4. Measure voltage between chassis ground and terminal IGSW at ECM connector. If 9-14 volts is present, go to step 6). If 9-14 volts is not present, remove and inspect IGN fuse located in instrument panel junction block, at rear of parking brake release lever. If fuse is blown, check for short to ground in wiring. Repair as necessary.
5. If IGN fuse is okay, disconnect ignition switch connector. With ignition switch in ON position, check for continuity between Black/White wire and Black/Red wire terminals at ignition switch. If continuity does not exist, replace ignition switch. If continuity exists, repair open circuit between battery and ignition switch, or between ignition switch and ECM.
6. Turn ignition on. Measure voltage between chassis ground and terminal MREL at ECM connector. If 9-14 volts is not present, replace ECM. If 9-14 volts is present, check EFI fuse located in engine compartment junction block, in front of left shock tower. If EFI fuse is blown, repair circuit.
7. If fuse is okay, check EFI main relay. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay is okay, check circuit between chassis ground and terminal MREL at ECM connector. Repair as necessary. If circuit is okay, repair circuit between battery and EFI fuse.

SC300 & SC400

1. Access ECM behind glove box. Turn ignition on. Connect voltmeter negative lead to terminal E1 and positive lead to terminal "B". See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10. If 9-14 volts is present, ECM keyed (ignition) power circuit is okay. Diagnose by symptom. See TESTS W/O CODES article. If 9-14 volts is not present, go to next step.
2. Check for an open circuit in wiring harness between ground and terminal E1 of ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
3. Measure voltage between chassis ground and terminal IGSW at ECM connector. If 9-14 volts is present, go to step 5). If 9-14 volts is not present, check the IGN fuse in driver side junction block behind left kick panel.
4. If fuse is blown, repair cause of blown fuse. If fuse is okay, check ignition switch. See STEERING COLUMN SWITCHES article. Replace ignition switch as necessary and retest. If ignition switch is okay, repair open circuit between battery and ignition switch, or between ignition switch and ECM.
5. Turn ignition on. Measure voltage between chassis ground and terminal M-REL at ECM connector. If 9-14 volts is not present, replace ECM. If 9-14 volts is present, check EFI fuse located in engine compartment fuse/relay block, at left front of engine compartment. If EFI fuse is blown, repair cause of blown fuse.
6. If fuse is okay, check EFI main relay located in engine compartment fuse/relay block, at left front of engine compartment. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay is okay, check circuit between chassis ground and terminal M-REL at ECM connector. If circuit is okay, repair circuit between battery and EFI fuse.

STARTER SIGNAL CIRCUIT

ENGINE SENSORS & SWITCHES

AIR-FUEL RATIO (AF) SENSOR HEATER RESISTANCE (ES300, CALIFORNIA MODELS ONLY)

Note. AF sensor is a heated oxygen sensor used on ES300 California models only.

Note. Bank No. 1 refers to bank that includes cylinder No. 1. Bank No. 2 refers to bank without cylinder No. 1. Sensor No. 1 refers to sensor closest to engine block. Sensor No. 2 refers to sensor furthest away from engine block.

AF sensor is located in bank No. 1 sensor No. 1 and bank 2 sensor 1 locations. Disconnect AF sensor connector. Measure resistance between terminals +B (No. 2) and HT (No. 1) of AF sensor connector. (Scheme 21) Resistance should be 11-16 ohms at 68°F (20°C). Replace AF sensor if resistance is not as specified.

Scheme 21

Except ES300

Disconnect accelerator position sensor connector. Accelerator position sensor is located on right side of throttle body. Measure resistance between circuits E2 and VC at accelerator pedal position sensor. (Scheme 22) On GS300 and SC300, resistance should be 1200-3200 ohms at 68°F (20°C). On GS400, LS400 and SC400, resistance should be 1640-3280 ohms at 68°F (20°C). If resistance is not as specified, replace accelerator pedal position sensor.

Scheme 22

CAMSHAFT SENSORS

Remove engine cover. Disconnect camshaft sensor 2-pin connector. Measure resistance between camshaft sensor terminals. Replace camshaft sensor if resistance is not as specified. See CAMSHAFT SENSOR RESISTANCE table.

CAMSHAFT SENSOR RESISTANCE

CRANKSHAFT SENSOR

Turn ignition off. Disconnect crankshaft sensor connector. Measure resistance between crankshaft sensor terminals. Replace crankshaft sensor if resistance is not as specified. See appropriate CRANKSHAFT SENSOR RESISTANCE table.

CRANKSHAFT SENSOR RESISTANCE (ES300)

CRANKSHAFT SENSOR RESISTANCE (GS300, GS400, SC300, SC400)

CRANKSHAFT SENSOR RESISTANCE (LS400)

Remove EGR temperature sensor. See REMOVE/INSTALL/OVERHAUL article. With sensing portion of EGR temperature sensor submerged in hot oil, measure resistance between terminals. (Scheme 23) Replace EGR temperature sensor if resistance is not as specified. See EGR TEMPERATURE SENSOR RESISTANCE table.

EGR TEMPERATURE SENSOR RESISTANCE

Scheme 23

1. Disconnect EGR position sensor connector. Position sensor is mounted on top of EGR valve. Measure resistance between terminals E2 and VC at EGR position sensor. (Scheme 24) If resistance is not 1500-4300 ohms, replace sensor. If resistance is 1500-4300 ohms, go to next step.
2. Turn ignition on. Access ECM behind glove box. Leave harness connectors attached to ECM. Disconnect vacuum hose from EGR valve. Backprobing, measure voltage between E2 and VC terminals at ECM connector. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
3. Apply 5 in. Hg to EGR valve. Backprobing, measure voltage between terminal EGLS and E2 at ECM connector. With 5 in. Hg applied, voltage should be 3.2-5.1 volts. With vacuum released, voltage should be.4-1.6 volts. If voltage is not as specified, replace EGR position sensor.

Scheme 24

ES300, GS300 & SC300

1. Turn ignition off. Disconnect negative battery cable. Drain coolant. Remove ECT sensor. On ES300, sensor is located on right top of engine, next to strut tower. On GS300 and SC300, sensor is located on left front of engine, behind power steering fluid reservoir.
2. On all models, with sensing portion of ECT sensor submerged in water measure resistance between terminals. (Scheme 23) Replace ECT sensor if resistance is not as specified. See «ECT SENSOR RESISTANCE»(ref-22514-S05974128712001010300000) table.

GS400, LS400 & SC400

Remove engine cover. Remove battery cover and air cleaner tube. Drain coolant. Remove throttle body. See appropriate THROTTLE BODY in REMOVE/INSTALL/OVERHAUL article. Remove ECT sensor. See REMOVAL & INSTALLATION article. With sensing portion of ECT sensor submerged in water, measure resistance between terminals. (Scheme 23) Replace ECT sensor if resistance is not as specified. See ECT SENSOR RESISTANCE table.

ECT SENSOR RESISTANCE

IAT Sensor Resistance

On all models, IAT sensor is part of Mass Airflow (MAF) sensor. Turn ignition off. Disconnect MAF sensor connector. Measure resistance between MAF sensor terminals THA and E2. (Scheme 25)or (Scheme 26). Replace MAF sensor if resistance is not as specified. See appropriate IAT SENSOR RESISTANCE table.

IAT SENSOR RESISTANCE (ES300)

IAT SENSOR RESISTANCE (GS300, GS400, LS400, SC300 & SC400)

Scheme 25

Scheme 26

KNOCK SENSOR

Remove knock sensor. See REMOVE/INSTALL/OVERHAUL article. On GS300 and SC300, knock sensors are located on front and rear left side of cylinder block. On ES300, GS400 and SC400, knock sensors are located in front of engine, on inside of either cylinder head, under intake manifold. On LS400, knock sensors are located in front of engine, under intake manifold, on inside of left cylinder head and left side of lower intake manifold. On all models, check for continuity between knock sensor terminal and knock sensor body (hex portion). If continuity exists, replace sensor.

MAF Sensor Resistance

Disconnect MAF sensor connector. Measure resistance between terminals THA and E2. Resistance should be as specified. See appropriate IAT SENSOR RESISTANCE table under INTAKE AIR TEMPERATURE (IAT) SENSOR . If resistance is not as specified, replace MAF sensor.

MAF Sensor Voltage

Leave MAF sensor connector attached. Turn ignition on. Backprobing, connect voltmeter positive lead to terminal VG and negative lead to terminal E2G at MAF sensor connector. (Scheme 27) Apply compressed air to MAF sensor. If voltage does not fluctuate while applying compressed air to MAF sensor, replace MAF sensor.

Scheme 27

OXYGEN SENSOR HEATER RESISTANCE

Note. Bank No. 1 refers to bank that includes cylinder No. 1. Bank No. 2 refers to bank without cylinder No. 1. Sensor No. 1 refers to sensor closest to engine block. Sensor No. 2 refers to sensor furthest away from engine block.

On ES300 (except California emission vehicles) bank No. 1 sensor No. 2, is located under driver's seat carpet, next to center counsel. On GS300 and SC300 bank No. 2 sensor No. 2 connector is located under left front passenger seat carpet. On LS400 bank No. 1 and 2 sensor No. 1 connector is located under rear air ducts. On GS400 and SC400, bank No. 1 and 2 sensor No. 2 connector is located under carpet. On all oxygen sensors, disconnect oxygen sensor connector. Measure resistance between terminals +B (No. 2) and HT (No. 1) of oxygen sensor connector. (Scheme 21) Replace oxygen sensor if resistance is not 11.0-16.0 ohms.

PARK/NEUTRAL POSITION (PNP) SWITCH

1. If PNP switch is out of adjustment, voltage signals may not be correctly applied to ECM, causing a Diagnostic Trouble Code (DTC) to set. Before assuming PNP switch is faulty, adjust PNP switch. See PARK/NEUTRAL POSITION (PNP) SWITCH under MISCELLANEOUS CONTROLS in ADJUSTMENTS article.
2. After switch adjustment is completed, recheck for codes. If DTC does not reset, PNP switch is okay. If DTC resets, remove PNP switch. Check for continuity between specified terminals of PNP switch. See appropriate PNP SWITCH CONTINUITY table. (Scheme 28) If continuity is not as specified, replace PNP switch. If continuity is as specified, install and adjust PNP switch.

PNP SWITCH CONTINUITY (ES300)

PNP SWITCH CONTINUITY (GS300, GS400, LS400, SC300 & SC400)

Scheme 28

PARK/NEUTRAL POSITION (PNP) SWITCH CIRCUIT

If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Perform appropriate circuit test. See TESTS W/CODES article.

1. Ensure ignition is off. Disconnect electrical connector from Throttle Position (TP) sensor on throttle body. Disconnect vacuum hose and apply vacuum to throttle opener. (Scheme 29)
2. Using ohmmeter, check resistance between specified terminals in relation to throttle position. With throttle fully closed, between terminals VTA and E2, resistance should be 200-6300 ohms. With throttle fully open, between terminals VAT and E2, resistance should be 2000-10,200 ohms. With throttle fully open, between terminals VC and E2, resistance should be 2500-5900 ohms. (Scheme 29) Replace components as necessary if resistance is not within specification.

GS300 & SC300

Disconnect Throttle Position (TP) sensor connector. TP sensor is located on left side of throttle body. Measure resistance between circuits E2 and VC at accelerator pedal position sensor. (Scheme 30) Resistance should be 1200-3200 ohms at 68°F (20°C). If resistance is not as specified, replace accelerator pedal position sensor.

Disconnect Throttle Position (TP) sensor connector. TP sensor is located on left side of throttle body. Measure resistance between terminals VC and E2 at accelerator pedal position sensor. (Scheme 31) Resistance should be 1250-2350 ohms at 68°F (20°C). If resistance is not as specified, replace accelerator pedal position sensor.

Scheme 29

Scheme 30

Scheme 31

VAPOR PRESSURE SENSOR CIRCUIT

1. Disconnect vapor pressure sensor connector. Turn ignition on. Measure voltage between vapor pressure sensor connector terminals.
2. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, check wiring harness between sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10. Repair as necessary. If wiring is okay, replace ECM.
3. Turn ignition off. Reconnect vapor pressure sensor connector. Excess ECM. Disconnect vapor pressure sensor vacuum hose. Turn ignition on.
4. Backprobing ECM harness connector, measure voltage between terminals and at ECM connector. Voltage reading should be as follows: 3.0-3.6 volts with no vacuum applied. 1.3-2.1 volts with.59 in. Hg (2.0 kPa) of vacuum applied. 4.2-4.8 volts with.22 psi (1.5 kPa) of pressure applied.

If voltage is not as specified, replace vapor pressure sensor.

Remove engine cover. Remove battery cover and air cleaner intake hose. Variable Valve Timing (VVT) sensor is located at top center of each cylinder head. Disconnect VVT sensor connector. Measure resistance between VVT sensor terminals. Resistance should be 835-1400 ohms at 14-122°F (-10-50°C), or 1060-1645 ohms at 122-212°F (50-100°C). If resistance is not as specified, replace VVT sensor.

Remove engine cover. For VVT sensor at bank No. 1, disconnect engine wire protector from upper intake manifold and bearing cap. For VVT sensor at bank No. 2, remove air cleaner intake hose. See VARIABLE VALVE TIMING SENSOR in REMOVE/INSTALL/OVERHAUL article. Remove Variable Valve Timing (VVT) sensors located at top center of each cylinder head. Disconnect VVT sensor connector. Measure resistance between VVT sensor terminals. Resistance should be 835-1400 ohms at 14-122°F (-10-50°C), or 1060-1645 ohms at 122-212°F (50-100°C). If resistance is not as specified, replace VVT sensor.

VEHICLE SPEED SENSOR (VSS)

Note. The following tests apply to ES300, GS300, SC300 and SC400 models only. GS400 and LS400 models use ABS information, received by multiplex communication, for vehicle speed. For diagnostic and repair information, refer to TESTS W/CODES article in the ENGINE PERFORMANCE section.

1. If speedometer operates, VSS No. 1 is okay. If speedometer does not operate, disconnect VSS No. 1 connector. Remove VSS No. 1 from transaxle/transmission. Connect battery positive lead to terminal No. 1 and negative lead to terminal No. 2. (Scheme 32)
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 32

GS300, SC300 & SC400

1. Disconnect electrical connector from VSS No. 1. Remove VSS from transmission. Measure resistance between VSS terminals. If resistance is 560-680 ohms, go to next step. If resistance is not 560-680 ohms, replace VSS.
2. Connect DVOM positive lead to terminal No. 1 (Green wire terminal) and negative lead to terminal No. 2 (Red wire terminal) at VSS. Set DVOM to lowest DC volt scale. While passing a magnet back and forth over tip of VSS, observe DVOM. Voltage should pulse (voltage is extremely low). If VSS does not operate as specified, replace VSS.

Fuel Pump ECU (Except ES300)

If circuit or component is faulty, a Diagnostic Trouble Code should set. Perform appropriate circuit test. See TESTS W/CODES article.

Ignitor

See SPARK TEST under IGNITION CHECKS in BASIC TESTING article.

Idle Air Control (IAC) Valve

See IDLE CONTROL SYSTEM .

RELAYS

Note. For cooling fan relay testing, see appropriate article under ENGINE COOLING.

Preliminary Information

Remove relay from engine compartment fuse/relay box. Determine which one of the following test procedures to perform. See appropriate RELAY TYPE & TEST PROCEDURE NUMBER table under RELAYS. (Scheme 33) Replace relay if it does not test as specified.

Test Procedure No. 1

1. Continuity should exist between terminals No. 1 and 2.
2. Continuity should not exist between terminals No. 3 and 5.
3. Apply battery voltage across terminals No. 1 and 2. Continuity should exist between terminals No. 3 and 5.

Test Procedure No. 2

1. Continuity should exist between terminals No. 1 and 3.
2. Continuity should not exist between terminals No. 2 and 4.
3. Apply battery voltage across terminals No. 1 and 3. Continuity should exist between terminals No. 2 and 4.

Test Procedure No. 3

1. Continuity should exist between terminals No. 1 and 2.
2. Continuity should not exist between terminals No. 3 and 4.
3. Apply battery voltage across terminals No. 1 and 2. Continuity should exist between terminals No. 3 and 4.

RELAY TYPE & TEST PROCEDURE NUMBER (ES300)

RELAY TYPE & TEST PROCEDURE NUMBER (GS300)

RELAY TYPE & TEST PROCEDURE NUMBER (GS400)

RELAY TYPE & TEST PROCEDURE NUMBER (LS400)

RELAY TYPE & TEST PROCEDURE NUMBER (SC300)

RELAY TYPE & TEST PROCEDURE NUMBER (SC400)

Scheme 33

Scheme 34

Scheme 35

Scheme 36

Scheme 37

ACIS Vacuum Switching Valve (VSV)

See ACOUSTIC CONTROL INDUCTION SYSTEM (ACIS) .

EGR Vacuum Switching Valve (VSV)

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

EVAP Vacuum Switching Valve (VSV)

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

Fuel Injectors

See FUEL SYSTEM .

Vapor Pressure Sensor Vacuum Switching Valve (VSV)

See FUEL EVAPORATION under EMISSION SYSTEMS & SUB-SYSTEMS.

FUEL INJECTOR CIRCUIT

If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Perform appropriate circuit test. See TESTS W/CODES article.

On ES300, remove engine cover. Turn ignition off. Disconnect appropriate injector connector. Measure resistance between injector terminals. Resistance should be about 13.4-14.2 ohms at 68°F (20°C). If resistance is not about 13.8 ohms at 68°F (20°C), replace injector.

GS400

Remove engine cover. Remove intake air tube. On all models, turn ignition off. Disconnect appropriate injector connector. Measure resistance between injector terminals. Resistance should be about 13.4-14.2 ohms at 68°F (20°C). If resistance is not about 13.4-14.2 ohms at 68°F (20°C), replace injector.

Remove engine cover. Remove battery clamp cover and air cleaner inlet. Remove intake air tube. Turn ignition off. Disconnect appropriate injector connector. Measure resistance between injector terminals. Resistance should be about 13.4-14.2 ohms at 68°F (20°C). If resistance is not about 13.4-14.2 ohms at 68°F (20°C), replace injector.

SC400

Turn ignition off. Remove engine cover. Remove battery cover and air cleaner inlet tube. Remove intake air connector tube. Disconnect appropriate injector connector. Measure resistance between injector terminals. Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is not 13.4-14.2 ohms at 68°F (20°C), replace injector.

Scheme 38

Scheme 39

1. On ES300, remove fuel injector. See REMOVE/INSTALL/OVERHAUL article. Connect Fuel Tube Adapter (23801-20040) to fuel filter outlet side. Ensure fuel injector "O" ring is installed. Install Injection Measuring Tool Set (09268-41046). (Scheme 38)or (Scheme 39). Install injector retainer clip. Attach a piece of vinyl tubing to bottom of fuel injector to prevent fuel splash. Put vinyl tubing into a graduated measuring cylinder. Go to step 4).
2. On GS300, SC300 and GS400, remove fuel injector. See REMOVE/INSTALL/OVERHAUL article. Disconnect fuel inlet hose from main tube. Install Fuel Tube Adapter (09268-52011) to fuel main tube. Ensure fuel injector "O" ring is installed. Install Injection Measuring Tool Set (09268-41047). (Scheme 38)or (Scheme 39). Install injector retainer clip. Attach a piece of vinyl tubing to bottom of fuel injector to prevent fuel splash. Put vinyl tubing into a graduated measuring cylinder. Go to step 4).
3. On SC400, remove fuel injector. See REMOVE/INSTALL/OVERHAUL article. Disconnect fuel inlet hose from main tube. Install Fuel Tube Adapter (09631-22020) to fuel main tube. Ensure fuel injector "O" ring is installed. Install Injection Measuring Tool Set (09268-41047). (Scheme 38)or (Scheme 39). Install injector retainer clip. Attach a piece of vinyl tubing to bottom of fuel injector to prevent fuel splash. Put vinyl tubing into a graduated measuring cylinder. Go to next step.
4. If using a Lexus scan tool, connect scan tool to Data Link Connector (DLC) No. 3. see scheme 14 Turn ignition on. DO NOT start engine. Turn scan tool on. Select ACTIVE TEST mode on scan tool. Using scan tool manufacturer's instructions, activate electric fuel pump, and go to next step. If Lexus scan tool is not available, manually activate fuel pump. See FUEL PUMP OPERATION (USING BATTERY VOLTAGE) under «FUEL PUMP OPERATION»(ref-22514-S11572674042001010300000), and go to next step.
5. Turn ignition on, engine off. Connect EFI Inspection Wiring (09842-30070) between fuel injector and a 12-volt battery for 15 seconds. Compare measured volume with specified volume. See appropriate FUEL INJECTOR VOLUME (15 SECONDS) table below. Test each injector 2-3 times. Turn injector off and check for leakage. Replace injector if one or more of the following conditions exists: Volume is not within specification. Difference in volume between injectors exceeds specification. On ES300 & LS400, more than one drop leaks from injector within one minute of disconnecting EFI inspection wiring from battery or turning injectors off using Lexus scan tool. On GS300, GS400, SC400, more than one drop leaks from injector within 12 minutes of disconnecting EFI inspection wiring from battery or turning injectors off using Lexus scan tool.

FUEL INJECTOR VOLUME (15 SECONDS) (ES300)

FUEL INJECTOR VOLUME (15 SECONDS) (S300, GS400, SC300 & SC400)

FUEL INJECTOR VOLUME (15 SECONDS) (LS400)

FUEL INJECTOR VOLUME (15 SECONDS) (SC300)

FUEL INJECTOR VOLUME (15 SECONDS) (SC400)

Using Battery Voltage

1. On ES300, GS300 and GS400, remove rear seat cushion. Remove fuel pump access cover. Remove floor service hole cover. Disconnect 5-pin connector from fuel pump and sending unit assembly. Connect a fused jumper wire between fuel pump connector terminal No. 5 and ground. (Scheme 40)
2. Connect one end of second fused jumper wire to fuel pump connector terminal No. 4 first and then connect other end of fused jumper wire to battery voltage. Ensure not to apply battery voltage to fuel pump for more than 10 seconds.
3. On LS400, SC300 and SC400, remove trunk floor mat. Remove trunk trim cover from behind rear seat in luggage compartment. Disconnect 2-pin fuel pump connector (NOT the sending unit connector) located behind rear speaker. Connect a fused jumper wire between fuel pump connector terminal No. 2 and ground. (Scheme 41)
4. Connect one end of second jumper wire to fuel pump connector terminal No. 1 first and then connect other end of fused jumper wire to battery voltage. Ensure not to apply battery voltage to fuel pump for more than 10 seconds.
5. On all models except GS300, fuel pump is operating if fuel pump operating sound can be heard or pulsations can be felt in fuel line near fuel filter. On GS300, check that fuel pressure pulsation damper screw rises when fuel pump operates. see scheme 34

Scheme 40

Scheme 41

ES300, GS300 & GS400

Remove rear seat cushion. Remove floor service hole cover. Disconnect 5-pin connector from fuel pump and sending unit assembly. Measure resistance between 5-pin fuel pump and sending unit connector terminals No. 4 and No. 5. (Scheme 40) Replace fuel pump if resistance is not 0.2-3.0 ohms at 68°F (20°C).

LS400, SC300 & SC400

Remove trunk floor mat. Remove trunk trim cover from behind rear seat in luggage compartment. Disconnect 2-pin fuel pump connector (NOT the sending unit connector) located behind rear speaker. Measure resistance between female terminals of fuel pump connector. Replace fuel pump if resistance is not 0.2-3.0 ohms at 68°F (20°C).

FUEL PUMP CONTROL CIRCUIT

1. Check fuel pump operation. See «FUEL PUMP OPERATION»(ref-22514-S11572674042001010300000). If fuel pump does not operate, go to next step. If fuel pump operates, check starter signal circuit. See «STARTER SIGNAL CIRCUIT»(ref-22514-S12760821962001010300000) under COMPUTERIZED ENGINE CONTROLS. Repair as necessary.
2. Check ECM power source circuit. See «ECM POWER SOURCE CIRCUIT (IGNITION KEYED)»(ref-22514-S18478141912001010300000) under COMPUTERIZED ENGINE CONTROLS. Repair as necessary. If circuit is okay, go to next step.
3. Check circuit opening relay. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. Replace circuit opening relay as necessary. If relay is okay, access ECM connectors behind glove compartment. Turn ignition on. Backprobing connector, measure voltage between chassis ground and terminal No. 18 (Green/Red wire) at ECM E9 connector. see scheme 7-10.
4. If battery voltage is not present, check for an open circuit in wiring harness between EFI main relay and circuit opening relay or between opening relay and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Replace as necessary. If battery voltage is present, go to next step.
5. Check fuel pump. See «FUEL PUMP RESISTANCE»(ref-22514-S32355046652001010300000). Replace fuel pump as necessary. If fuel pump is okay, check for an open circuit in wiring harness between circuit opening relay and fuel pump or between fuel pump and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

GS300, GS400, SC300 & SC400

If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Perform appropriate circuit test. See TESTS W/CODES article.

1. Check fuel pump operation. See «FUEL PUMP OPERATION»(ref-22514-S11572674042001010300000). If fuel pump operates, go to step 6). If fuel pump does not operate, go to next step.
2. Check fuel pump relay. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS RELAYS & SOLENOIDS. Replace relay as necessary. If relay is okay, go to next step.
3. Remove trim cover from behind rear seat in luggage compartment. Disconnect 2-pin fuel pump connector (NOT sending unit connector). Measure resistance between female terminals of fuel pump connector. Resistance should be 0.2-3.0 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel pump.
4. Check circuit opening relay. See «RELAYS»(ref-22514-S03759569252001010300000) under MODULES, MOTORS RELAYS & SOLENOIDS. Replace relay as necessary. If relay is okay, check for open in wiring harness between main relay and fuel pump or between fuel pump and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
5. Measure voltage between chassis ground and terminal No. 4 (Green/Black wire) of ECM E12 connector. see scheme 7-10. If voltage is 9-14 volts, no problem is indicated at this time. If voltage is not 9-14 volts, locate and repair open between battery and ECM.
6. Disconnect fuel pump resistor located in left front of engine compartment. Measure resistance between resistor terminals. If resistance is not.70-.76 ohm, replace resistor. If resistance is.70-.76 ohm, check for open circuit between fuel pump relay and fuel pump resistor, or fuel pump resistor and fuel pump. Repair as necessary.

FUEL PUMP PRESSURE

To check fuel pump pressure, see FUEL SYSTEM in BASIC TESTING article.

Disconnect fuel pump resistor located in left front of engine compartment. Measure resistance between resistor terminals. If resistance is not .70-.76 ohm, replace resistor.

FUEL PRESSURE REGULATOR

This is a returnless fuel system and is not equipped with a fuel pressure regulator on fuel rail. To check in tank fuel pressure regulator, perform FUEL PRESSURE test under FUEL SYSTEM in BASIC TESTING article.

FUEL SYSTEM PRESSURE

To check fuel system pressure, see FUEL SYSTEM in BASIC TESTING article.

IAC Valve Resistance

Disconnect IAC valve connector. Measure resistance between terminals +B (Black/Yellow wire) and RSC (Yellow/Black wire), and between terminals +B (Black/Yellow wire) and RSO (Red/White wire) at IAC valve. (Scheme 43) If resistance is not 17-24.5 ohms at 14-122°F (-10-50°C), or 22-29 ohms at 122-212°F (50-100°C), replace IAC valve. If resistance is as specified, reconnect IAC valve connector. Go to next procedure.

Scheme 42

Scheme 43

Air Assist System

1. Ensure engine is at normal operating temperature. Ensure idle speed is 650-750 RPM. Ensure transmission is in Neutral. Turn A/C off. Connect Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1. (Scheme 42)
2. Increase engine speed to about 900-1300 RPM for about 10 seconds. Release throttle. Engine speed should decrease to idle speed of 650-750 RPM. Stop engine. Disconnect air hose from air pipe. see scheme 39 Plug hose end, and cap off the hose pipe fitting.
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 and repair vacuum leak.

IGNITION SYSTEM

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

To check ignitor, perform SPARK TEST under IGNITION CHECKS in BASIC TESTING article.

IGNITION COIL RESISTANCE

1. Disconnect electrical connector and distributor wire from ignition coil. To measure primary resistance, measure resistance between terminals of ignition coil.
2. To measure secondary resistance, measure resistance between positive wire terminal at ignition coil and coil secondary tower. See «IGNITION COIL POSITIVE TERMINAL IDENTIFICATION»(ref-22514-S32892107942001010300000) table. If resistance is not as specified, replace ignition coil. See appropriate IGNITION COIL RESISTANCE table below.

IGNITION COIL POSITIVE TERMINAL IDENTIFICATION

IGNITION COIL RESISTANCE (ES300) - Ohms

IGNITION COIL RESISTANCE (GS300) - Ohms

IGNITION COIL RESISTANCE (LS400 & SC400) - Ohms

IGNITION COIL RESISTANCE (SC300) - Ohms

EMISSION SYSTEMS & SUB-SYSTEMS

EXHAUST GAS RECIRCULATION (EGR) SYSTEM

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

If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Perform appropriate circuit test. See TESTS W/CODES article.

For EGR position sensor testing, see EXHAUST GAS RECIRCULATION (EGR) POSITION SENSOR under ENGINE SENSORS & SWITCHES.

1. Remove engine cover. Remove emission control valve set and wire harness cover. Disconnect vacuum hoses and electrical connector from VSV. See appropriate illustration in VACUUM DIAGRAMS article. Measure resistance between VSV terminals. If resistance is 27-33 ohms at 68°F (20°C), go to next step. If resistance is not 27-33 ohms, replace VSV.
2. Check for continuity between VSV case and each terminal of VSV connector (this checks for an internal short). If no continuity exists, go to next step. If continuity exist, replace VSV.
3. Apply compressed air to port "E". (Scheme 49) If air flows out of port "G", go to next step. If air does not flow out of port "G", replace VSV.
4. Apply battery voltage and ground across VSV terminals. Apply compressed air to port "E". If air flows out of port "F", VSV is functioning properly. If air does not flow out of port "F", replace VSV.

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.

For EGR temperature sensor testing, see EXHAUST GAS RECIRCULATION (EGR) TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES.

Remove EGR VCV. Connect a vacuum pump to EGR VCV port "S" (Scheme 44) Plug EGR VCV port "Z". Pump vacuum pump 3 times. On each pump of vacuum pump, vacuum should increase to about 11.8 in. Hg and decrease to about 8.6 in. Hg. After the third pump, vacuum should stabilize at 4.4-7.1 in. Hg. If vacuum is not as specified, replace EGR VCV.

Scheme 44

EVAP Canister (ES300)

Visually inspect EVAP canister and hoses for cracks and damage. Check for clogged filter, and stuck check valve and diaphragm. Disconnect hoses from EVAP canister ports. (Scheme 45) Plug port "E". Replace EVAP canister if it does not function as follows

1. Hold port "B" closed and apply .26 psi of compressed air to port "A" on top of canister. Air should flow from port "D".
2. Plug port "B" and "D" and apply .26 psi of compressed air to port "A". Air should not flow from port "C".
3. Connect a vacuum pump to port "B". Apply 1.01 in. Hg vacuum. 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 1.01 in. Hg vacuum. Air should flow into port "B".

Scheme 45

EVAP Canister (GS300 & GS400)

Visually inspect EVAP canister and hoses for cracks and damage. Disconnect hoses from EVAP canister ports. (Scheme 46) Replace EVAP canister if it does not function as follows

1. Hold purge port closed and apply .26 psi of compressed air to EVAP port on top of canister. Air should flow from air drain port.
2. Plug purge and air drain port, and apply .26 psi of compressed air to EVAP port. Air should not flow from air inlet port.
3. Connect a vacuum pump to purge port. Apply 1.01 in. Hg vacuum. With air inlet port plugged, vacuum should hold. With air inlet port unplugged, vacuum should release.
4. Connect vacuum pump to EVAP port and plug air inlet port. Apply 1.01 in. Hg vacuum. Air should flow into purge port.

Scheme 46

EVAP Canister (LS400)

Visually inspect EVAP canister and hoses for cracks and damage. Check for clogged filter, and stuck check valve and diaphragm. Disconnect hoses from EVAP canister ports. (Scheme 47) Replace EVAP canister if it does not function as follows

1. Hold port "B" closed and apply .26 psi of compressed air to port "A" on top of canister. Air should flow from port "D".
2. Plug port "B" and "D" and apply .26 psi of compressed air to port "A". Air should not flow from port "C".
3. Connect a vacuum pump to port "B". Apply .62 in. Hg vacuum. With port "C" plugged, vacuum should hold. With port "C" unplugged, vacuum should release.
4. Connect a vacuum pump to port "A". Apply .39 in. Hg vacuum. With port "C" plugged, air should flow into port "B".

Scheme 47

EVAP Canister (SC300 & SC400)

Visually inspect EVAP canister and hoses for cracks and damage. Check for clogged filter, and stuck check valve and diaphragm. Disconnect hoses from EVAP canister ports. (Scheme 48) Replace EVAP canister if it does not function as follows

1. Hold port "B" closed and apply .26 psi of compressed air to port "A" on top of canister. Air should flow from port "D".
2. Plug port "B" and "D" and apply .26 psi of compressed air to port "A". Air should not flow from port "C".
3. Connect a vacuum pump to port "B". Apply 1.01 in. Hg vacuum. 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 .29 in. Hg vacuum. Air should flow into port "B".

Scheme 48

EVAP Vacuum Switching Valve (VSV) ES300

1. Remove engine cover. Remove control valve set and wire harness cover. Disconnect electrical connector and vacuum hoses from VSV. Measure resistance between VSV terminals. If resistance is 27-33 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal of VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Apply compressed air to port "E". (Scheme 49) Air should not flow or flow with difficulty from port "G". If VSV function as specified, go to next step. If VSV does not function as specified, replace VSV.
4. Apply battery voltage across VSV terminals. Apply compressed air to port "E". If air flows out of port "G", VSV is functioning properly. If air does not flow out of port "G", replace VSV.

EVAP Vacuum Switching Valve (VSV) GS300 & GS400

1. Disconnect electrical connector and vacuum hoses from VSV. Measure resistance between VSV terminals. If resistance is 33-39 ohms at 68°F (20°C), go to next step. On GS400, if resistance is 30-34 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal of VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Apply compressed air to port "E". (Scheme 49) Ensure not to apply more than 13.5 psi of compressed air to EVAP VSV. Air should not flow from port "G". If VSV function as specified, go to next step. If VSV does not function as specified, replace VSV.
4. Apply battery voltage and ground to EVAP VSV terminals. Apply compressed air to port "E". If air flows out of port "G", VSV is functioning properly. If air does not flow out of port "G", replace VSV.

EVAP Vacuum Switching Valve (VSV) SC300 & SC400

1. Disconnect electrical connector and vacuum hoses from VSV. Measure resistance between VSV terminals. On SC300, if resistance is 27-33 ohms at 68°F (20°C), go to next step. On SC400, if resistance is 30-34 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal of VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Apply compressed air to port "E". (Scheme 49) Air should not flow from port "G". If VSV function as specified, go to next step. If VSV does not function as specified, replace VSV.
4. Apply battery voltage across VSV terminals. Apply compressed air to port "E". If air flows out of port "G", VSV is functioning properly. If air does not flow out of port "G", replace VSV.

EVAP Vacuum Switching Valve (VSV) LS400

1. Disconnect electrical connector and vacuum hoses from VSV. See appropriate illustration in VACUUM DIAGRAMS article. Measure resistance between VSV terminals. If resistance is 30-34 ohms at 68°F (20°C), go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal of VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Apply compressed air through port "E". (Scheme 49) Air should not flow from port "G". If VSV function as specified, go to next step. If VSV does not function as specified, replace VSV.
4. Apply battery voltage and ground to EVAP VSV terminals. Apply compressed air through port "E". If air flows out of port "G", VSV is functioning properly. If air does not flow out of port "G", replace VSV.

Vapor Pressure Sensor

For vapor pressure sensor testing, see VAPOR PRESSURE SENSOR under ENGINE SENSORS & SWITCHES.

Vapor Pressure Sensor Vacuum Switch Valve (VSV) (Except ES300)

1. VSV is mounted on top of EVAP canister. Disconnect electrical connector and vacuum hoses from vapor pressure sensor VSV. See appropriate illustration in VACUUM DIAGRAMS article. On GS400 remove vapor pressure sensor VSV. Measure resistance between vapor pressure sensor VSV terminals. If resistance is 33-39 ohms (on GS300, ES300), 37-44 ohms (on LS400) at 68°F (20°C), go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between vapor pressure sensor VSV case and each terminal of VSV connector (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace vapor pressure sensor VSV.
3. Apply air pressure to VSV port "E". (Scheme 49) If air flows from port "G", go to next step. If air does not flow from port "G", replace VSV.
4. Apply battery voltage and ground across VSV terminals. Apply compressed air to port "E". If air flows out of port "F", VSV is functioning properly. If air does not flow from port "F", replace VSV.

Scheme 49

PCV Valve

Remove PCV valve from valve cover. Inspect PCV hoses, connections and gaskets for leaks and damage. Apply compressed air to cylinder head side of PCV valve. Air should pass freely through PCV valve. Apply compressed air to intake manifold side of PCV valve. Air should not pass freely through PCV valve. Clean or replace PCV valve if air does not flow as specified.

Timing Oil Control Valve Resistance (GS300 & SC300)

Disconnect connector from appropriate oil control valve. Oil control valves are located at front top or each cylinder head. Measure resistance between terminals or appropriate oil control valve. Resistance should be 5.5-12 ohms at 68°F (20°C). If resistance is not as specified, replace oil control valve.

Timing Oil Control Valve Resistance (GS400, LS400 & SC400)

Remove engine cover. Remove battery cover, air cleaner and intake air hose. Disconnect connector from appropriate oil control valve. Oil control valves are located at front top or each cylinder head. Measure resistance between terminals or appropriate oil control valve. Resistance should be 6.9-7.9 ohms at 68°F (20°C). If resistance is not as specified, replace oil control valve.

VARIABLE VALVE TIMING (VVT) SENSOR

See VARIABLE VALVE TIMING SENSOR under ENGINE SENSORS & SWITCHES.

MISCELLANEOUS CONTROLS

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

COOLING FAN SYSTEM

For electric cooling fan testing, see appropriate article under ENGINE COOLING.

TRANSMISSION

For transmission diagnostic information, see TRANSMISSION SERVICE & REPAIR article.