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

OXYGEN SENSOR OPERATION

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

FUEL CUT SYSTEM OPERATION

1. 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 at least the following specification. 2500 RPM.
3. Release throttle lever. When throttle lever is released, injectors should stop operating momentarily until engine speed decreases to 1400 RPM.

FUEL INJECTOR OPERATION

Start engine. Using a stethoscope, listen for clicking from each injector (or feel injector for vibration). If clicking is not heard, check for loose connection at injector connector, or no voltage signal at injector connector.

Checking Fuel Pump Operation (Using Scan Tool)

1. Connect scan tool to Data Link Connector (DLC) No. 3. Turn ignition on. DO NOT start engine.
2. Using 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 filter.

Fuel Pump Operation (Using Battery Voltage)

1. Remove trunk floor mat. Remove trunk trim panel. Disconnect fuel pump connector.
2. Connect battery voltage to specified terminals on fuel pump connector to activate fuel pump. see scheme 20 Fuel pump is operating if fuel pump operating sound can be heard or pulsations can be felt in fuel line near fuel filter.

IAC System Operation

Start engine. While shutting engine off, listen for a click from IAC valve. If click is heard, IAC system is okay. If click is not heard, perform IAC system circuit test.

IAC Valve Operation

Remove IAC valve from throttle body. Connect battery positive lead to terminals B1 and B2 of IAC valve. To close IAC valve pintle, repeatedly ground terminals S1, S2, S3 and S4 in sequence. To open IAC valve pintle, repeatedly ground terminals S4, S3, S2 and S1 in sequence. Replace IAC valve if pintle does not open and close as specified.

Operation Test

1. Remove "V" bank cover from top of engine. Disconnect EGR valve connector. Drain coolant. Remove and inspect EGR valve. Replace EGR valve if pintle inside valve is contaminated with heavy carbon deposits. If pintle is not heavily contaminated, connect jumper wires between battery positive terminal and terminals B1 and B2 of EGR valve connector. (Scheme 9)
2. Connect jumper wires to battery negative terminal (these wires will be used to ground terminals at EGR valve). Check EGR valve operation by opening and closing the pintle as follows. If pintle does not open and close, replace EGR valve. Closing Pintle

Ground terminal S4 with one jumper wire and terminal S3 with other jumper wire. Keep terminal S3 grounded. Disconnect jumper wire from terminal S4 and connect it to terminal S2. Keep terminal S2 grounded. Disconnect jumper wire from terminal S3 and connect it to terminal S1. Keep terminal S1 grounded. Disconnect jumper wire from terminal S2 and connect it to terminal S4. Continue to follow this sequence until pintle is closed.

1. Opening Pintle

Ground terminal S1 with one jumper wire and terminal S2 with other jumper wire. Keep terminal S2 grounded. Disconnect jumper wire from terminal S1 and connect it to terminal S3. Keep terminal S3 grounded. Disconnect jumper wire from terminal S2 and connect it to terminal S4. Keep terminal S4 grounded. Disconnect jumper wire from terminal S3 and connect it to terminal S1. Continue to follow this sequence until pintle is closed.

Scheme 9

See also:
• WIRING DIAGRAMS