Engine Controls - System & Component Testing: Other Lexus SC II

AIR INDUCTION SYSTEMS

Note. Information for SC430 is not available from manufacturer.

Intake Air Control Valve

1. Install a 3-way vacuum "T" fitting in vacuum hose between Intake Air Control Valve (IACV) actuator and ACIS Vacuum Switch Valve (VSV). (Scheme 194) 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). Ensure vacuum reading momentarily reads about 9.8 in. Hg and IACV actuator rod pulls down. If vacuum is not as specified or actuator rod fails to pull down, go to next step.
3. Remove IACV. Apply about 15.8 in. Hg to IACV actuator. If IACV actuator rod does not move, turn adjusting screw on IACV assembly. If IACV actuator rod still 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 IACV actuator. If diaphragm holds vacuum, check vacuum tank. See «ACIS VACUUM TANK»(ref-151784-S16293545432003010800000).

Scheme 194

ACIS Vacuum Tank

1. Disconnect vacuum hoses from vacuum tank. Vacuum tank is located under air intake chamber. (Scheme 194)
2. Apply compressed air to port "A". (Scheme 195) 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.
3. If ACIS vacuum tank does not operate as specified, replace ACIS vacuum tank. If ACIS vacuum tank operates as specified, go to «ACIS Vacuum Switching Valve»(ref-151784-S30779045872003010800000).

Scheme 195

ACIS Vacuum Switching Valve

1. Remove bolt and A/T fluid dipstick and guide. Remove and discard "O" ring. Remove emission control valve set from top of vacuum tank. Disconnect vacuum hoses and electrical connector from ACIS Vacuum Switching Valve (VSV). (Scheme 194)
2. Measure resistance between VSV terminals. If resistance is not 39-45 ohms at 68°F (20°C), replace ACIS VSV. If resistance is 39-45 ohms, 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 compressed air to port "E". (Scheme 196) Air should flow out of filter, but not out of port "F". Using jumper wires, 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 196

1. Remove throttle body. See «THROTTLE BODY»(ref-151794-S40075325892003010800000) under FUEL SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article. Remove upper and lower intake manifolds. See «KNOCK SENSOR»(ref-151794-S11650124812003010800000) under SENSORS & SWITCHES in REMOVAL & INSTALLATION - EXCEPT GX470 article. Install a 3-way vacuum "T" fitting in vacuum hose between Intake Air Control Valve (IACV) actuator and ACIS Vacuum Switching Valve (VSV). (Scheme 197) Reinstall intake manifolds 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. Snap accelerator to Wide Open Throttle (WOT) position. Vacuum should not exist during WOT and IACV actuator rod should return. If vacuum is not as specified or actuator valve rod fails to pull out, go to next step.
3. 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, check vacuum hoses and vacuum tank. See «ACIS VACUUM TANK»(ref-151784-S08084686822003010800000).

Scheme 197

Disconnect vacuum hoses from vacuum tank. Vacuum tank is located under front of intake manifold. Apply compressed air to port "A". (Scheme 198) 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 of vacuum 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, check vacuum switching valve. See ACIS VACUUM SWITCHING VALVE.

Scheme 198

1. Remove engine cover. Remove air cleaner inlet tube. Remove throttle body. See «THROTTLE BODY»(ref-151794-S40075325892003010800000) under FUEL SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article. Remove intake manifold assembly. See «KNOCK SENSOR»(ref-151794-S11650124812003010800000) under SENSORS & SWITCHES in REMOVAL & INSTALLATION - EXCEPT GX470 article. Disconnect vacuum hoses and electrical connector from Vacuum Switching Valve (VSV). (Scheme 198) Remove VSV. Measure resistance between VSV terminals. If resistance is 33-39 ohms, go to next step. If resistance is not 33-39 ohms, 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 VSV port "E". (Scheme 196) 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.

ECM BACK-UP POWER CIRCUIT (BATTERY)

If circuit or components are faulty, a Diagnostic Trouble Code (DTC) should set. Retrieve DTCs and perform appropriate diagnostic test. See appropriate SELF-DIAGNOSTICS article.

ECM POWER SOURCE CIRCUIT (IGNITION ON)

Note. For information on engine immobilizer, see THEORY & OPERATION article.

STARTER SIGNAL CIRCUIT

Note. For information on engine immobilizer, see THEORY & OPERATION article.

GS300 & IS300

Disconnect accelerator pedal position sensor connector. (Scheme 199) Measure resistance between terminals E2 and VC. If resistance is between 1200-3200 ohms, accelerator pedal position sensor is okay. If resistance is not as specified, replace accelerator pedal position sensor.

Scheme 199

GS430, LS430 & SC430

Disconnect accelerator pedal position sensor connector. Sensor is mounted above accelerator pedal. (Scheme 200) Measure resistance between terminals VCP1 and EP1. Also measure resistance between VCP2 and EP2. If resistance is between 1500-6000 ohms on both circuits, accelerator pedal position sensor is okay. If resistance is not as specified, replace accelerator pedal position sensor.

Scheme 200

CAMSHAFT POSITION SENSOR

Remove engine cover. Locate Camshaft Position (CMP) sensor. See CAMSHAFT POSITION SENSOR LOCATION table. Remove intake air connector pipe, if necessary. Disconnect CMP sensor 2-pin connector. Measure resistance between CMP sensor terminals. Replace CMP sensor if resistance is not as specified. See CAMSHAFT POSITION SENSOR RESISTANCE table.

CAMSHAFT POSITION SENSOR LOCATION

CAMSHAFT POSITION SENSOR RESISTANCE

CRANKSHAFT POSITION SENSOR

Crankshaft Position sensor (CKP) is a pick-up coil that is mounted next to crankshaft pulley. Turn ignition off. Disconnect CKP sensor connector. Measure resistance between CKP sensor terminals. Replace CKP sensor if resistance is not as specified. See CRANKSHAFT POSITION SENSOR RESISTANCE table.

CRANKSHAFT POSITION SENSOR RESISTANCE

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

1. Ensure ignition is off. Locate ECT sensor. See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION»(ref-151784-S29536205122003010800000) table. Remove ECT sensor.
2. Place probe end of ECT sensor and thermometer in container of water. Attach ohmmeter between ECT sensor terminals. Heat water and note that resistance is within specification in relation to temperature. (Scheme 201) Replace ECT sensor if resistance is not within specification.
3. Using NEW gasket, install ECT sensor. Tighten ECT sensor to 14 ft. lbs. (19 N.m). Fill cooling system.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

Scheme 201

HEATED 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 behind catalytic converter.

1. On GS300 and IS300, locate heated oxygen sensor to be tested. (Scheme 202) Connector for bank No. 2, sensor No. 2 is located under front passenger's seat carpet.
2. On GS430 and LS430, one sensor is located in each exhaust manifold and one sensor is located behind each catalytic converter. Connector for bank No. 1, sensor No. 2 is located behind driver's seat carpet. Connector for bank No. 2, sensor No. 2 is located under front passenger's seat carpet.
3. On SC430, one sensor is located in each exhaust manifold and one sensor is located behind each catalytic converter. Connector for bank No. 1, sensor No. 2 is located behind driver's side console carpet. Connector for bank No. 2, sensor No. 2 is located behind front passenger's side console carpet. (Scheme 203)and (Scheme 204). Go to next step.
4. On all models, disconnect oxygen sensor connector to be tested. Measure resistance between terminals B+ and HT at oxygen sensor connector. (Scheme 205) Replace oxygen sensor if resistance is not 11-16 ohms at 68°F (20°C) or 23-32 ohms at 1,472°F (800°C).

Scheme 202

Scheme 203

Scheme 204

Scheme 205

INTAKE AIR TEMPERATURE (IAT) SENSOR

Note. For SC430, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - SC430 article.

IAT Sensor Resistance

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 206) Replace MAF sensor if resistance is not as specified. See INTAKE AIR TEMPERATURE (IAT) SENSOR RESISTANCE table.

INTAKE AIR TEMPERATURE (IAT) SENSOR RESISTANCE

Scheme 206

KNOCK SENSOR

Remove knock sensor. See KNOCK SENSOR under SENSORS & SWITCHES in REMOVAL & INSTALLATION - EXCEPT GX470 article. Check for continuity between knock sensor terminal and knock sensor body (hex portion). If continuity does not exist, knock sensor is okay. If continuity exists, replace knock sensor.

MASS AIRFLOW (MAF) SENSOR

Note. For SC430, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - SC430 article.

MAF Sensor Resistance

Disconnect MAF sensor connector. Measure resistance between MAF sensor terminals THA and E2 at MAF sensor. (Scheme 206) Resistance should be as specified. See INTAKE AIR TEMPERATURE (IAT) SENSOR RESISTANCE table. 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 207) Blow compressed air through MAF sensor. If voltage does not fluctuate while blowing compressed air through MAF sensor, replace MAF sensor.

Scheme 207

PARK/NEUTRAL POSITION (PNP) SWITCH

Note. For SC430, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - SC430 article.

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»(ref-151794-S03812214932003010800000) under SENSORS & SWITCHES in REMOVAL & INSTALLATION - EXCEPT GX470 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 «PNP SWITCH CONTINUITY»(ref-151784-S24705652632003010800000) table. (Scheme 208) If continuity is not as specified, replace PNP switch. If continuity is as specified, install and adjust PNP switch.

PNP SWITCH CONTINUITY

Scheme 208

PARK/NEUTRAL POSITION (PNP) SWITCH CIRCUIT

If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Retrieve DTCs and perform appropriate diagnostic test. See appropriate SELF-DIAGNOSTICS article.

THROTTLE POSITION (TP) SENSOR

Note. For SC430, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - SC430 article.

Disconnect Throttle Position (TP) sensor connector. Do not confuse TP sensor with accelerator pedal position sensor. Both sensors have 4-pin connectors and are mounted on throttle body (Scheme 209) Measure resistance between terminals E2 and VC at TP sensor. Resistance should be 1200-3200 ohms at 68°F (20°C). If resistance is not 1200-3200 ohms, replace TP sensor.

Scheme 209

GS430 & LS430

Disconnect Throttle Position (TP) sensor 4-pin connector. (Scheme 210) Measure resistance between terminals VC and ETA at TP sensor. Resistance should be 1250-2350 ohms at 68° F (20° C). If resistance is not 1250-2350 ohms, replace TP sensor.

Scheme 210

VAPOR PRESSURE SENSOR

For vapor pressure sensor testing, see appropriate test under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

VARIABLE VALVE TIMING SENSOR

Note. GS300 and IS300 models are equipped with variable valve timing but use the camshaft position sensor instead of Variable Valve Timing (VVT) sensors to determine camshaft position. For testing procedure, see CAMSHAFT POSITION SENSOR .

1. Variable Valve Timing (VVT) sensors are located on top of engine and are mounted on the intake side of each cylinder head. To access left VVT sensor, remove engine cover. Disconnect engine wire protector from upper intake manifold and camshaft bearing cap. Disconnect VVT sensor 2-pin connector with Green and Red wires. To access right VVT sensor, remove engine cover. Remove intake air connector pipe. Disconnect VVT sensor 2-pin connector with Yellow and Blue wires.
2. Measure resistance between VVT sensor terminals. Replace sensor if resistance is not as specified. See «VARIABLE VALVE TIMING SENSOR RESISTANCE»(ref-151784-S29335859012003010800000) table.

VARIABLE VALVE TIMING SENSOR RESISTANCE

VEHICLE SPEED SENSOR (VSS)

Remove VSS from rear of transmission. See VEHICLE SPEED SENSOR under SENSORS & SWITCHES in REMOVAL & INSTALLATION article. Using an ohmmeter, measure resistance between VSS connector terminals. Resistance should be 560-680 ohms. Using a voltmeter set to AC voltage, measure voltage between VSS connector terminals. Place a magnet close to front of VSS and quickly remove (to generate a voltage pulse). If voltage pulse is not generated, replace VSS.

Throttle Control Motor (GS300 & IS300)

1. Disconnect throttle control motor 4-pin connector. Throttle control motor is mounted on side of throttle body. Measure resistance between terminals No. 3 (CL-) and 4 (CL+) at throttle control motor. (Scheme 211) Resistance should be 4.2-5.2 ohms at 68°F (20°C). If resistance is not 4.2-5.2 ohms, replace throttle control motor. If resistance is as specified, go to next step.
2. Measure resistance between terminals No. 1 (M+) and 2 (M-) at throttle control motor connector. (Scheme 211) Resistance should be.3-100 ohms at 68°F (20°C). If resistance is not.3-100 ohms, replace throttle control motor.

Scheme 211

Throttle Control Motor (GS430, LS430 & SC430)

Disconnect control throttle motor 2-pin connector. Throttle control motor is mounted on side of throttle body. Measure resistance between terminals No. 1 (M+) and 2 (M-) at throttle control motor connector. (Scheme 212) Resistance should be.3-100 ohms at 68°F (20°C). If resistance is not.3-100 ohms, replace throttle control motor.

Scheme 212

RELAYS

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

ACIS Vacuum Switching Valve (VSV)

See appropriate ACOUSTIC CONTROL INDUCTION SYSTEM (ACIS) test under AIR INDUCTION SYSTEMS .

EVAP Vacuum Switching Valve

See appropriate test under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

Fuel Injectors

See FUEL CONTROL under FUEL SYSTEMS.

Canister Closed Valve Vacuum Switching Valve

See appropriate test under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

Pressure Switching Valve Vacuum Switching Valve

See appropriate test under DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article.

FUEL SYSTEMS

For procedure, see FUEL SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article.

FUEL DELIVERY

Note. The following procedure is for checking fuel pump operation using battery voltage. To check fuel pump operation using Lexus scan tool, see FUEL PUMP OPERATION under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article.

Fuel Pump Resistance

Remove rear seat cushion. Remove floor service hole cover. Disconnect 5-pin connector from fuel pump and sending unit assembly. Measure resistance between terminals No. 4 and 5 at fuel pump and sending unit 5-pin connector. see scheme 28 Replace fuel pump if resistance is not 0.2-3.0 ohms at 68°F (20°C).

Fuel Pump Control Circuit (GS300 & GS430)

Note. For information on engine immobilizer, see THEORY & OPERATION article.

1. Check fuel pump operation. See «FUEL PUMP OPERATION (USING BATTERY VOLTAGE)»(ref-151784-S40776072172003010800000). If fuel pump does not operate, go to next step. If fuel pump operates, go to step 6.
2. Remove trunk trim cover from behind rear seat in luggage compartment. Disconnect fuel pump Electronic Control Unit (ECU) 10-pin connector in left side of luggage compartment. Turn ignition on. Measure voltage between ground and terminal No. 10 (Black/Red wire) at fuel pump ECU connector. (Scheme 213) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check for open or short in wiring harness between EFI main relay and fuel pump ECU. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
3. With ignition switch turned to START position, measure voltage between terminals No. 5 (White/Black wire) and No. 8 (Black/Blue wire) at fuel pump ECU. (Scheme 213) If voltage is 3.3-4.3 volts, go to step 5. If voltage is not 3.3-4.3 volts, go to next step.
4. Check for open or short in White/Black wire between fuel pump ECU and ground. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If White/Black wire is okay, check for open or short in Black/Blue wire between fuel pump ECU and ECM. Repair as necessary. If both circuits are okay, replace ECM and retest system.
5. Check fuel pump. See «FUEL PUMP RESISTANCE»(ref-151784-S22620672442003010800000). Replace fuel pump as necessary. If fuel pump is okay, check for an open circuit in wiring harness between fuel pump ECU and fuel pump. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If wiring is okay, replace fuel pump ECU and retest.
6. Check for an open or short in Black/Red wire between fuel pump ECU and ECM. See appropriate WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

Scheme 213

Fuel Pump Pressure (All Models)

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

Fuel Pressure Regulator (All Models)

All models use a returnless fuel system and are not equipped with a fuel pressure regulator on fuel rail. Fuel pressure regulator is mounted to fuel pump assembly and is located in fuel tank. To check in tank fuel pressure regulator, perform FUEL PRESSURE test under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article.

Fuel Injector Circuit

If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Retrieve DTCs and perform appropriate diagnostic test. See appropriate SELF-DIAGNOSTICS article.

Fuel Injector Resistance

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 13.4-14.2 ohms, replace injector.

Fuel Injector Volume

1. Remove fuel injector. See «FUEL RAILS & INJECTORS»(ref-151794-S14340385202003010800000) under FUEL SYSTEM in REMOVAL & INSTALLATION - EXCEPT GX470 article. Disconnect fuel inlet hose from main fuel tube. Install Fuel Tube Adapter (09268-52011) to fuel main tube. Connect fuel hose from Injection Measuring Tool Set (09268-41047) to fuel tube adapter. (Scheme 214)
2. Ensure fuel injector "O" ring is installed. Connect fuel injector to fuel hose and install injector retainer clip. (Scheme 214) Attach a piece of vinyl tubing to bottom of fuel injector to prevent fuel splash. Place vinyl tubing into a graduated measuring cylinder.
3. If using a Lexus scan tool, connect scan tool to Data Link Connector (DLC) No. 3. see scheme 10 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)»(ref-151784-S40776072172003010800000) procedure under FUEL DELIVERY, and then go to next step.
4. Connect EFI Inspection Wiring (09842-30070) between fuel injector and a 12-volt battery. Do not apply voltage to fuel injector for more than 15 seconds. Compare measured volume with specified volume. See «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-151784-S13403188902003010800000) table. Test each injector 2-3 times. Replace fuel injector if fuel injector volume is not within specification.
5. Ensure difference between fuel injector volume on all fuel injectors is within specification. See «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-151784-S13403188902003010800000) table. Disconnect fuel injector tester. Ensure fuel leakage from end of fuel injector does not exceed one drop within 12 minutes (one minute on LS430). Replace fuel injector if leakage exceeds specification. Disconnect negative battery cable. Remove test equipment and reconnect all components.

FUEL INJECTOR VOLUME SPECIFICATIONS

Scheme 214

IS300, LS430 & SC430

Locate fuel pump resistor, located under protective cover on driver's side strut tower. Disconnect fuel pump resistor Black 2-pin connector. Measure resistance between resistor terminals. If resistance is not .30-.35 ohm, replace resistor.

1. Connect scan tool to DLC3 to monitor engine RPM. see scheme 10 Remove engine cover. Start and warm engine to operating temperature. Turn A/C off. Use a stethoscope to listen for injector operating noise (or feel for vibration with finger).
2. Increase engine speed to 3000 RPM. Release throttle lever. When throttle lever is released, injectors should stop operating momentarily until engine speed decreases to 1000 RPM. Shut engine off. Remove scan tool.

1. Connect scan tool to DLC3 to monitor engine RPM. see scheme 10 Remove engine cover. Start and warm engine to operating temperature. Turn A/C off. Use a stethoscope to listen for injector operating noise (or feel for vibration with finger).
2. Increase engine speed to 2500 RPM. Release throttle lever. When throttle lever is released, injectors should stop operating momentarily until engine speed decreases to 1400 RPM. Shut engine off. Remove scan tool.

IGNITION SYSTEMS

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

EMISSION SYSTEMS & SUB-SYSTEMS

Note. For information on engine immobilizer, see THEORY & OPERATION article.

FUEL EVAPORATION SYSTEM

Note. Fuel EVAP system may also referred to as On-Board Refilling Vapor Recovery (ORVR) system.

For EVAP system component testing, see appropriate SELF-DIAGNOSTICS article.

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.

THROTTLE CONTROLS

Note. Information for SC430 is not available from manufacturer.

THROTTLE BODY

Note. Before performing the following procedure, ensure no Diagnostic Trouble Codes (DTCs) are present. See appropriate SELF-DIAGNOSTICS article. Repair any DTCs that are present before continuing with this test.

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 ELECTRIC COOLING FANS article in ENGINE COOLING.

TRANSMISSION

For transmission diagnostic information, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.