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

Testing & Diagnostics 2 illustrations ~1746 words

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. On GS400, ES300 and LS400, remove engine cover. On all models, 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. 3500 RPM (ES300). 3000 RPM (GS300 and SC300). 2500 RPM (GS400, LS400 and SC400).
  3. Release throttle lever. When throttle lever is released, injectors should stop operating momentarily until engine speed decreases to 1400 RPM (1200 RPM on ES300, 1000 RPM on GS300 and SC300).

FUEL INJECTOR OPERATION

Remove engine cover. On all models, 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. Also check for no voltage signal at injector connector. See FUEL INJECTOR RESISTANCE .

System Operation

  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 Fused Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1. see scheme 37 DLC No. 1 is located right of intake air chamber.
  2. Increases engine speed to about 1000 RPM for about 5 seconds. Release throttle. Idle speed should decrease to 650-750 RPM. If engine speed is not as specified, disconnect jumper wire from DLC No. 1, then go to next procedure.

IAC Valve Operation

Remove IAC valve from throttle body. Using a 12-volt battery, connect positive lead to terminal +B (Black/Yellow wire) of IAC valve. see scheme 38 Connect negative lead to terminal RSC (Yellow/Black wire). IAC valve should close. Connect negative lead to terminal RSO (Red/White wire). IAC valve should open. Replace IAC valve if it does not operate as specified.

Scheme 14

Scheme 14: IAC Valve Operation
Scheme 14: IAC Valve Operation

Throttle System Operation (GS300 & SC300)

  1. Ensure all accessories are off. Ensure throttle linkage moves smoothly. Turn ignition on. Rotate accelerator pedal position sensor lever and listen for running sound from throttle motor. Ensure friction sound does not exist. If running sound exists, go to step 3). If running sound does not exist, check throttle control motor. See SYSTEM/COMPONENT TESTS article.
  2. If throttle control motor is okay, check for open or short circuit in wiring harness between throttle control motor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, go to next step.
  3. Using Lexus scan tool, connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 14 Switch Lexus scan tool to CURRENT DATA. Ensure MIL does not illuminate. Rotate accelerator pedal position sensor lever to full open position. THROTTLE POS on Lexus scan tool should indicate 60 percent or more. If results are as specified, go to step 5). If results are not as specified, check accelerator pedal position sensor. See SYSTEM/COMPONENT TESTS article.
  4. If accelerator pedal position sensor is okay, check for open or short circuit in wiring harness between accelerator pedal position sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.
  5. Clear trouble codes. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in TESTS W/CODES article. Start engine and ensure MIL does not illuminate. Allow engine to reach normal operating temperature. Ensure all accessories are off. Place transmission in Neutral position. Turn A/C on and then off and check idle speed. Idle speed should be between 700-800 with A/C on. Idle speed should be between 650-750 with A/C off.
  6. With engine idling, pinch air assist hose located next to throttle motor. Idle speed should drop and return back to normal. If idle speed changes as specified, go to next step. If idle speed does not change as specified, check throttle body. If throttle body is okay, check for open or short circuit in wire harness. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, go to next step. Drive vehicle to ensure vehicle performs properly.

Throttle System Operation (GS400 & SC400)

  1. Remove engine cover. Ensure throttle linkage moves smoothly. Turn ignition on. Rotate accelerator pedal position sensor lever and listen for running sound from throttle motor. Ensure friction sound does not exist. If running sound exists, go to step 3). If running sound does not exist, check throttle control motor. See SYSTEM/COMPONENT TESTS article.
  2. If throttle control motor is okay, check for open or short circuit in wiring harness between throttle control motor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, go to next step.
  3. Ensure all accessories are off. If not using Lexus scan tool, go to step 5). If using Lexus scan tool, connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 14 Switch Lexus scan tool to CURRENT DATA. Ensure MIL does not illuminate. Rotate accelerator pedal position sensor lever to full open position. THROTTLE POS on Lexus scan tool should indicate 60 percent or more. If results are as specified, go to step 7). If results are not as specified, check accelerator pedal position sensor. See SYSTEM/COMPONENT TESTS article.
  4. If accelerator pedal position sensor is okay, check for open or short circuit in wiring harness between accelerator pedal position sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.
  5. On GS400, access ECM at left front of engine compartment. Backprobing, measure voltage between ECM E3 connector terminal No. 15 (Blue wire) and No. 18 (Brown wire). On SC400, access ECM behind glove box. Backprobing, measure voltage between ECM E16 connector terminal No. 21 (Yellow/Red wire) and No. 18 (Brown wire). On all models, with ignition switch in ON position and throttle fully closed, voltage should be.3-.9 volts. With ignition switch in ON position and throttle fully open, voltage should be 3.2-4.8 volts. If voltage is as specified, go to next step. If voltage is not as specified, check accelerator pedal position sensor. See SYSTEM/COMPONENT TESTS article.
  6. If accelerator pedal position sensor is okay, check for open or short circuit in wiring harness between accelerator pedal position sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.
  7. Clear trouble codes. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in TESTS W/CODES article. Start engine and ensure MIL does not illuminate. Allow engine to reach normal operating temperature. Place transmission in Neutral position. Turn A/C on and then off and check idle speed. Idle speed should be 700-800 RPM. Drive vehicle to ensure vehicle performs properly.

Throttle System Operation (LS400)

  1. Remove engine cover. Ensure throttle linkage moves smoothly. Turn ignition on. Rotate accelerator pedal position sensor lever and listen for running sound from throttle motor. Ensure friction sound does not exist. If running sound exists, go to step 3). If running sound does not exist, check throttle control motor. See «THROTTLE CONTROL MOTOR»(ref-22514-S12418338592001010300000) under MODULES MOTORS, RELAY & SOLENOIDS.
  2. If throttle control motor is okay, check for open or short circuit in wiring harness between throttle control motor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, go to next step.
  3. Ensure all accessories are off. If not using Lexus scan tool, go to step 5). If using Lexus scan tool, connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 14 Switch Lexus scan tool to CURRENT DATA. Ensure MIL does not illuminate. Rotate accelerator pedal position sensor lever to full open position. THROTTLE POS on Lexus scan tool should indicate 60 percent or more. If results are as specified, go to step 7). If results are not as specified, check accelerator pedal position sensor. See «ACCELERATOR PEDAL POSITION SENSOR»(ref-22514-S36217300972001010300000) under ENGINE SENSORS & SWITCHES.
  4. If accelerator pedal position sensor is okay, check for open or short circuit in wiring harness between accelerator pedal position sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.
  5. Access ECM behind glove box. Backprobing, measure voltage between ECM E13 connector terminal No. 21 (Pink wire) and No. 18 (Brown wire). See appropriate wiring diagram in WIRING DIAGRAMS article. see scheme 7-10. With ignition switch in ON position and throttle fully closed, voltage should be.3-.9 volts. With ignition switch in ON position and throttle fully open, voltage should be 3.2-4.8 volts. If voltage is as specified, go to next step. If voltage is not as specified, check accelerator pedal position sensor. See «ACCELERATOR PEDAL POSITION SENSOR»(ref-22514-S36217300972001010300000) under ENGINE SENSORS & SWITCHES.
  6. If accelerator pedal position sensor is okay, check for open or short circuit in wiring harness between accelerator pedal position sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.
  7. Clear trouble codes. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in TESTS W/CODES article. Start engine and ensure MIL does not illuminate. Allow engine to reach normal operating temperature. Place transmission in Neutral position. Turn A/C on and then off and check idle speed. Idle speed should be 700-800 RPM. Drive vehicle to ensure vehicle performs properly.

VARIABLE VALVE TIMING (VVT) SYSTEM OPERATION

  1. Start and run engine. Allow engine to reach normal operating temperature. Disconnect suspect Oil Control Valve (OCV) connector. Connect fused jumper wires between positive battery terminal and suspect OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. (Scheme 15)
  2. If engine speed does not change with OCV disconnected and changes (rough idle) with fused jumper wires connected, system is okay. If results are not as specified, check OCV. See «CAMSHAFT TIMING OIL CONTROL VALVE»(ref-22514-S03826317852001010300000). If OCV is okay, check VVT pulley. See DTC P1349 test in TESTS W/CODES article. If VVT pulley is okay, check wiring to OCV and ECM. See WIRING DIAGRAMS article.

Timing Oil Control Valve Operation

Remove oil control valve. Connect a fused jumper wire between battery voltage and terminal No. 1 of oil control valve. (Scheme 15) Connector a second fused jumper wire between ground and terminal No. 2 of oil control valve. Spindle should move away from oil control valve connector. Remove battery voltage from connector. Spindle should move towards oil control valve connector. If oil control valve operation is not as specified, replace oil control valve.

Scheme 15

Scheme 15: Timing Oil Control Valve Operation
Scheme 15: Timing Oil Control Valve Operation

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