Engine Controls - System/component Tests: Other Lexus LS II

ACIS SYSTEM CHECK

1. Connect vacuum gauge between IACV actuator and VSV. 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
3. System is okay if it operates as specified. If system does not operate as specified, perform ACIS CIRCUIT test.

ACIS VACUUM SWITCHING VALVE (VSV)

1. Disconnect vacuum hoses and electrical connector from VSV. Remove VSV if necessary. Measure resistance between VSV terminals. If resistance is 39-45 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. Blow air through port "E". (Scheme 16) Air should flow out of filter, but not out of port "F". Apply battery voltage to VSV terminals. Blow air through port "E". Air should flow out of port "F". If VSV does not function as specified, replace VSV.

Scheme 16

ECM GROUND CIRCUITS

ECM is located underneath top of passenger-side carpet (behind glove box) and is mounted to floor panel. Measure resistance between engine (ground) and specified terminals at 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 Diagnostic Trouble Code (DTC) should set. See TESTS W/CODES article.

ECM POWER SOURCE CIRCUIT (IGNITION KEYED)

1. Access ECM behind glove box. Leave electrical connectors attached to ECM. Turn ignition on. Backprobing connector, connect voltmeter negative lead to terminal No. 16 (Brown wire) at ECM E12 connector (this terminal is grounded). see scheme 1
2. Connect voltmeter positive lead to terminal No. 14 (Black/Yellow wire) at ECM E11 connector. If battery voltage is present, ECM keyed (ignition) power circuit is okay. If battery voltage is not present, go to next step.
3. Check for an for an open circuit in wiring harness between ground and terminal No. 16 (Brown wire) at ECM E12 connector. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-22206) article. Repair as necessary. If wiring is okay, go to next step.
4. Measure voltage between chassis ground and terminal No. 9 (Black/Orange wire) at ECM E11 connector. If battery voltage is present, go to step 6). If battery voltage is not present, remove and inspect IGN fuse. 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 No. 24 (Black/Orange wire) at ECM E11 connector. If battery voltage is not present, replace ECM. If battery voltage is present, check EFI fuse. If EFI fuse is blown, repair circuit.
7. If fuse is okay, check EFI main relay. See «RELAYS»(ref-22208-S30489838132001010300000) under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay is okay, check circuit between chassis ground and terminal No. 24 at ECM E11 connector. Repair as necessary. If circuit is okay, repair circuit between battery and EFI fuse.

STARTER SIGNAL CIRCUIT

ENGINE SENSORS & SWITCHES

CAMSHAFT SENSORS

1. Turn ignition off. Disconnect camshaft sensor 2-pin connector. LS400 is equipped with 2 sensors. One sensor is located in each distributor housing.
2. Measure resistance between camshaft sensor terminals. Replace camshaft sensor if resistance is not as specified. See «CAMSHAFT SENSOR RESISTANCE»(ref-22208-S02528945702001010300000) table.

CAMSHAFT SENSOR RESISTANCE

CRANKSHAFT SENSOR

Turn ignition off. Disconnect crankshaft sensor connector. Sensor is located at front of engine, near crankshaft pulley. Measure resistance between crankshaft sensor terminals. Replace crankshaft sensor if resistance is not as specified. See CRANKSHAFT SENSOR RESISTANCE table.

CRANKSHAFT SENSOR RESISTANCE

EXHAUST GAS RECIRCULATION (EGR) TEMPERATURE SENSOR

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 17) Replace EGR temperature sensor if resistance is not as specified. See EGR TEMPERATURE SENSOR RESISTANCE table.

Scheme 17

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

Remove ECT sensor. See REMOVE/INSTALL/OVERHAUL article. With sensing portion of ECT sensor submerged in water, measure resistance between terminals. (Scheme 17) Replace ECT sensor if resistance is not as specified. See ECT SENSOR RESISTANCE table.

ECT SENSOR RESISTANCE

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

INTAKE AIR TEMPERATURE (IAT) SENSOR RESISTANCE

Scheme 18

KNOCK SENSOR

Remove knock sensor. See REMOVE/INSTALL/OVERHAUL article. Knock sensors are located on either side of cylinder block. Check for continuity between knock sensor terminal and knock sensor body (hex portion). If continuity exists, replace sensor.

MAF Sensor Voltage

Leave MAF sensor connector attached. Turn ignition on. Backprobing connector, connect voltmeter positive lead to VG terminal at MAF sensor connector. See MASS AIRFLOW METER (MAF) SENSOR TERMINALS table. Connect voltmeter negative lead to remaining terminal to be checked. If voltage does not fluctuate while blowing air through MAF sensor, replace MAF sensor.

MASS AIRFLOW METER (MAF) SENSOR TERMINALS

OXYGEN SENSOR HEATER RESISTANCE

Disconnect oxygen sensor connector. Measure resistance between terminals +B and HT of oxygen sensor connector. (Scheme 19) Replace oxygen sensor if resistance is not as specified. See OXYGEN SENSOR HEATER RESISTANCE table.

OXYGEN SENSOR HEATER RESISTANCE

Scheme 19

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»(ref-22210) 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-22208-S07500364842001010300000) table. (Scheme 20) If continuity is not as specified, replace PNP switch. If continuity is as specified, install and adjust PNP switch.

PNP SWITCH CONTINUITY

Scheme 20

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.

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. (Scheme 21) Measure resistance between sub-TP sensor terminals. See SUB-TP SENSOR RESISTANCE table. (Scheme 22) If resistance is not as specified, adjust sub-TP sensor. See SUB-THROTTLE POSITION (SUB-TP) SENSOR in ADJUSTMENTS article. Recheck resistance. If resistance is still not as specified, replace sub-TP sensor.

SUB-TP SENSOR RESISTANCE

Scheme 21

Scheme 22

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 between specified terminals of TP sensor connector. See TP SENSOR RESISTANCE table. (Scheme 22) 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

VAPOR PRESSURE SENSOR CIRCUIT

1. Turn ignition off. Disconnect vapor pressure sensor connector. Vapor pressure sensor is located in left front of engine compartment. Measure voltage between Blue/Red wire and Brown wire at vapor pressure sensor harness connector.
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»(ref-22206) article. Repair as necessary. If wiring is okay, replace ECM.
3. Reconnect vapor pressure sensor connector. Access ECM behind glove box. Backprobing ECM harness connector, measure voltage between terminals No. 18 (Pink/Green wire) at ECM E11 connector and No. 22 (Brown wire) at ECM E13 connector. see scheme 1 Go to next step.
4. Disconnect vacuum hose from vapor pressure sensor. 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.

Scheme 23

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 23)
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.
3. 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.
4. 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.

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

1. Access ECM behind glove box. Using scan tool, measure frequency output at terminal No. 12 (Yellow wire) of ECM E11 connector. see scheme 1 With vehicle speed at 37 MPH, frequency output should be 42.5 Hz. With vehicle speed at 60 MPH, frequency output should be 68.4 Hz. If frequency is as specified, go to next step. If frequency is not as specified, go to step 5).
2. Turn ignition off. Backprobing connector, check continuity of Yellow wire between terminal No. 12 at ECM E11 connector and terminal No. 8 at instrument cluster 22-pin Gray connector. If continuity exists, go to next step. If continuity does not exist, repair open in Yellow wire between ECM and instrument cluster.
3. Remove cover and power source unit from back of instrument cluster for access to printed circuit plate. (Scheme 24) Check for continuity between the following speedometer terminals of printed circuit plate. (Scheme 25) If continuity does not exist, replace printed circuit plate. If continuity exists, go to next step. "A" and b6. "B" and a13. "C" and b5.
4. Disconnect all instrument cluster connectors. Measure resistance between terminal No. 8 at 22-pin connector and terminal No. 5 at "F" connector at instrument cluster. (Scheme 26) If resistance is 6300-6800 ohms, replace speedometer and retest. If resistance is not 6300-6800 ohms, replace power source unit and retest.
5. Turn ignition off. Check for continuity between terminals No. 4 (Red wire) and No. 9 (Green wire) at ECM E13 connector. see scheme 1 If continuity exists, replace ECM and retest. If continuity does not exist, go to next step.
6. Check VSS. See «VEHICLE SPEED SENSOR (VSS) NO»(ref-22208-S35823280682001010300000). 1. Replace VSS as necessary and recheck system. If VSS is okay, repair wiring harness between ECM and VSS. Retest system.

Scheme 24

Scheme 25

Scheme 26

Fuel Pump ECU

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 .

Sub-Throttle Actuator Motor (Vehicles With Traction Control)

Disconnect electrical connector from sub-throttle actuator motor. (Scheme 27) 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 27

RELAYS

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

Preliminary Information

Remove relay from engine compartment relay box. Determine which one of the following test procedures to perform. See RELAY TYPE & TEST PROCEDURE NUMBER table. see scheme 14-18. Replace relay if it does not test as specified.

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 (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.

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.

FUEL INJECTOR RESISTANCE

Turn ignition off. Disconnect injector connector. Measure resistance between injector terminals. Resistance should be about 13.4-14.2 ohms. If resistance is not about 13.4-14.2 ohms, replace injector.

Scheme 28

1. Remove fuel injector. See «REMOVE/INSTALL/OVERHAUL»(ref-22239) article. Connect Injection Measuring Tool Set (9268-41046). (Scheme 28) Attach a piece of vinyl tubing to bottom of fuel injector to prevent fuel splash. Put vinyl tubing into a graduated measuring cylinder.
2. If Lexus scan tool is not available, go to next step. If using a Lexus scan tool, connect scan tool to Data Link Connector (DLC) No. 3. Turn ignition on. DO NOT start engine. Using scan tool manufacturer's instructions, activate electric fuel pump. Go to step 4).
3. Remove trunk floor mat. Remove trunk trim panel. Disconnect fuel pump connector. Connect battery voltage to specified terminals on fuel pump connector to activate fuel pump. (Scheme 29) Go to next step.
4. 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 «FUEL INJECTOR VOLUME (15 SECONDS)»(ref-22208-S00120815282001010300000) 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 29

FUEL PUMP RESISTANCE

Remove trim cover from behind rear seat in luggage compartment. Disconnect 2-pin fuel pump connector (NOT the sending unit connector). 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-22208-S36130552642001010300000). 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-22208-S30489838132001010300000) 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-22208-S30489838132001010300000) 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»(ref-22206) 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. (Scheme 16) 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.

FUEL PUMP RESISTOR

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

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

1. Disconnect electrical connector and vacuum hoses from fuel pressure regulator VSV. See «FUEL PRESSURE REGULATOR VSV LOCATION»(ref-22208-S33967431562001010300000) table. Measure resistance between VSV terminals. If resistance is 37-44 ohms, go to next step. If resistance is not as specified, replace VSV.
2. Check for continuity between VSV case and each terminal of VSV (this checks for an internal short). If continuity does not exist, go to next step. If continuity exists, replace VSV.
3. Blow air through port "E" of VSV. (Scheme 30) Air should flow out of port "G". Apply battery voltage across VSV terminals. Blow air through port "E". Air should flow out of filter. If VSV does not operate as specified, replace VSV.

FUEL PRESSURE REGULATOR VSV LOCATION

Scheme 30

FUEL PRESSURE REGULATOR VSV CONTROL CIRCUIT

1. Check fuel pressure regulator VSV. See «FUEL PRESSURE REGULATOR VACUUM SWITCHING VALVE (VSV)»(ref-22208-S18446933272001010300000). Replace VSV as necessary. If VSV is okay, access ECM connectors behind glove box. Turn ignition on.
2. Leave harness connectors attached to ECM. Backprobing connector, measure voltage between chassis ground and terminal No. 9 (Red/White wire) at ECM E12 connector. (Scheme 16)
3. 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-22234) article. If fuel pressure regulator is okay, replace ECM and retest.

FUEL SYSTEM PRESSURE

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

IAC System Circuit

Perform IAC valve resistance and operation tests. If IAC valve resistance and operation are okay, check for open or shorted circuit between EFI main relay and IAC valve, and between IAC valve and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If circuits are okay, IAC system circuit is okay.

IAC Valve Resistance

Remove IAC valve from throttle body. Measure resistance between the following terminals of IAC valve connector. (Scheme 29)

1. Terminals B1 and S1.
2. Terminals B1 and S3.
3. Terminals B2 and S2.
4. Terminals B2 and S4.

If resistance is not as specified, replace IAC valve. See IAC VALVE RESISTANCE table.

IAC VALVE RESISTANCE

IGNITION SYSTEM

Note. For basic ignition checks, see IGNITION CHECKS in 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).

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-22208-S00742453232001010300000) table. If resistance is not as specified, replace ignition coil. See «IGNITION COIL RESISTANCE»(ref-22208-S13140253442001010300000) table.

IGNITION COIL POSITIVE TERMINAL IDENTIFICATION

IGNITION COIL RESISTANCE - 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.

1. Remove "V" bank cover from top of engine. Ensure coolant temperature is less than 127°F (53°C). Block wheels. Start engine. Shift transmission into Neutral. Connect Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1.
2. Run engine at 3500 RPM. Ensure coolant temperature is less than 127°F (53°C).
3. While engine is running at 3500 RPM, disconnect jumper wire and observe engine RPM. If engine speed remains steady, go to next step. If engine speed does not remain steady, check for faulty EGR system components.
4. Ensure engine coolant temperature is at least 131°F (55°C). Reconnect jumper wire between terminals TE1 and E1. While engine is running at 3500 RPM, disconnect jumper wire and observe engine RPM. If engine speed increases 100-300 RPM, EGR system is okay. If engine speed does not increase 100-300 RPM, check for faulty EGR system components.

Scheme 31

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

EVAP Canister

Visually inspect EVAP canister and hoses for cracks and damage. Plug port "E". Disconnect all hoses from canister. (Scheme 32) 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. 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 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 Hg vacuum. Air should flow into port "B".

Scheme 32

EVAP Vacuum Switching Valve (VSV)

1. Disconnect electrical connector and vacuum hoses from VSV. See appropriate illustration in «VACUUM DIAGRAMS»(ref-22209) 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. Blow air through port "E". If air does not flow out of port "G", go to next step. If air flows out of port "G", replace VSV.
4. Apply battery voltage across VSV terminals. Blow 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

1. Disconnect vapor pressure sensor VSV vacuum hoses. VSV is mounted on top of EVAP canister. Apply air pressure to VSV port "E". (Scheme 33) If air flows from port "G", go to next step. If air does not flow from port "G", replace VSV.
2. Apply battery voltage across VSV terminals. Blow air through port "E". If air flows out of port "F", VSV is functioning properly. If air does not flow from port "F", replace VSV.

Scheme 33

PCV Valve

Remove PCV valve from valve cover. 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 not pass freely through PCV valve. Clean or replace PCV valve if air does not flow as specified.

DASHPOT

1. Run engine at operating temperature. Ensure idle speed is 650-750 RPM. Turn off engine. Remove cap, filter and separator from end of dashpot. (Scheme 34) Start engine. Increase engine speed to 4000 RPM. Ensure cooling fan is not running.
2. Fully extend dashpot rod by using finger to cover hole inside area where separator was installed in dashpot. Release throttle. If engine speed is not 2500 RPM, turn dashpot adjusting screw as necessary. Installing separator, filter (coarse side up) and cap.

Scheme 34

THROTTLE OPENER

Run engine at operating temperature. Ensure idle speed is 650-750 RPM. Disconnect vacuum hose from throttle opener, and plug hose. 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. Turn throttle opener adjustment screw as necessary. (Scheme 35)

THROTTLE OPENER SET SPEED SPECIFICATIONS

Scheme 35

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.

COOLING FAN SYSTEM

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

TRANSMISSION

For transmission diagnostic information, see appropriate TRANSMISSION SERVICE & REPAIR section.