HEATED OXYGEN SENSOR OPERATION
If circuit or component is faulty, a Diagnostic Trouble Code (DTC) should set. Retrieve DTCs and perform appropriate diagnostic test. SeeSELF-DIAGNOSTICS - INTRODUCTION article.
Fuel Pump Operation (Using Lexus Scan Tool)
- Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 8or see scheme 9. Turn ignition on. Turn scan tool on. DO NOT start engine.
- Select ACTIVE TEST mode on scan tool. Using Lexus scan tool manufacturer's instructions, activate electric fuel pump. Fuel pump is operating if fuel pump operating sound can be heard or pulsations can be felt in fuel line near fuel rail.
- If fuel pump does not operate, check for faulty fusible link/fuses. See appropriate wiring diagram in WIRING DIAGRAMS article. Check for faulty circuit opening relay or EFI main relay in fuse/relay box at left front of engine compartment. Check for faulty fuel pump, ECM or poor wiring connections.
Fuel Pump Operation (Using Battery Voltage)
- 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 41)
- 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. Do not apply battery voltage to fuel pump for more than 10 seconds.
- Fuel pump is operating if fuel pump operating sound can be heard or pulsations can be felt in fuel line near fuel rail. If fuel pump does not operate, replace fuel pump.
Scheme 41
Fuel Injector Operation
Remove engine cover. Using a stethoscope, listen for clicking from each injector (or feel injector for vibration using a screwdriver) with engine running or cranking. If clicking is not heard, check for loose connection at fuel injector connector or fuel injector resistance. See FUEL INJECTOR RESISTANCE . If fuel injector is okay, check for no voltage signal at suspect injector connector.
FUEL CUT SYSTEM OPERATION
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). Increase engine speed to at least 3500 RPM. Release throttle lever. When throttle lever is released, injectors should stop operating momentarily until engine speed decreases to 1200 RPM. Shut engine off. Remove scan tool.
SYSTEM OPERATION
- Ensure engine is at normal operating temperature. Ensure idle speed is 650-750 RPM. Ensure transmission is in Neutral. Turn A/C off. Connect Fused Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1 located at front of air intake chamber. (Scheme 42) On ES300, DLC No. 1 is located on front of air intake chamber. On RX300, DLC No. 1 is located on left side of engine compartment, behind fuse box.
- On all models, engine speed should increase to about 1000 RPM for about 5 seconds then return to idle (650-750 RPM). If engine speed is as specified, go to «AIR ASSIST SYSTEM»(ref-2784-S19173361992000041300000). If engine speed is not as specified, disconnect jumper wire from DLC No. 1. Check IAC valve operation. Replace IAC valve as necessary. If IAC valve is okay, check for open or short in IAC valve wiring. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace ECM.
Scheme 42
IAC VALVE OPERATION
Remove throttle body. See THROTTLE BODY in REMOVAL, OVERHAUL & INSTALLATION article. Remove IAC valve from throttle body. Check IAC valve position. IAC valve should be in half open position. (Scheme 43) Connect IAC valve connector to IAC valve. Turn ignition on and observe IAC valve operation. IAC valve should move to fully closed, fully open and then to half open position within 5 seconds of turning ignition on. If IAC valve operation is not as specified, replace IAC valve and retest.
Scheme 43
VARIABLE VALVE TIMING (VVT) SYSTEM OPERATION
If VVT system circuits or components are faulty, a Diagnostic Trouble Code (DTC) should set. Retrieve DTCs and perform appropriate diagnostic test. See SELF-DIAGNOSTICS - INTRODUCTION article.
Oil Control Valve Operation
Remove Oil Control Valve (OCV) to be tested. Connect a fused jumper wire between battery voltage and terminal No. 1 at OCV. (Scheme 44) Connect another jumper wire between negative battery terminal and terminal No. 2 at OCV and note OCV plunger operation. With battery voltage applied, plunger on end of OCV should extend. Disconnect a jumper wire. Without battery voltage applied, plunger should retract. If OCV operation is not as specified, replace OCV.
