Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA2002HIGHLANDER 4WD L4-2.4L (2AZ-FE)REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTFUEL DELIVERY AND AIR INDUCTIONTESTING AND INSPECTION
2002 Toyota Highlander 4WD L4-2.4L (2AZ-FE)
Fuel Delivery and Air Induction: Testing and Inspection
2002 Toyota Highlander 4WD L4-2.4L (2AZ-FE)SECTION Testing and Inspection
ON-VEHICLE INSPECTION
1. INSPECT AIR-FUEL RATIO COMPENSATION SYSTEM
a. Measure voltage between terminals of the engine ECM.
CAUTION: Connect test leads from the back side of the connector with the ECM connected.
HINT: Voltage between terminals of the engine ECM is kept constant regardless of the voltage of A/F sensor.
b. Connect the TOYOTA hand-held tester to the DLC3.
c. Select "DATA MONITOR" - "A/FS B1 S1", "A/FS B2 S1" and "O2S B1 S2" to display the monitor.
d. Warm up the A/F sensor with the engine speed at 2,500 r.p.m for approx. 2 minutes.
e. Keep the engine speed at 2,500 r.p.m and confirm that the displays of "A/FS B1 S1", and "A/FS B2 S1" are as shown in the illustration.
CAUTION: The illustration differs from the real display. Only TOYOTA hand-held tester displays the waveform of A/F sensor.
f. Confirm that the display of "O2S B1 S2" changes between 0 V to 1V with the engine speed at 2,500 r.p.m.
2. INSPECT FUEL CUT OFF RPM
a. Increase the engine speed to at least 3,500 r.p.m.
b. Use a sound scope to check for injector operating noise.
c. Check that when the throttle lever is released, injector operation noise stops momentarily and then resumes.
1. INSPECT AIR-FUEL RATIO COMPENSATION SYSTEM
a. Measure voltage between terminals of the engine ECM.
CAUTION: Connect test leads from the back side of the connector with the ECM connected.
HINT: Voltage between terminals of the engine ECM is kept constant regardless of the voltage of A/F sensor.
b. Connect the TOYOTA hand-held tester to the DLC3.
c. Select "DATA MONITOR" - "A/FS B1 S1", "A/FS B2 S1" and "O2S B1 S2" to display the monitor.
d. Warm up the A/F sensor with the engine speed at 2,500 r.p.m for approx. 2 minutes.
e. Keep the engine speed at 2,500 r.p.m and confirm that the displays of "A/FS B1 S1", and "A/FS B2 S1" are as shown in the illustration.
CAUTION: The illustration differs from the real display. Only TOYOTA hand-held tester displays the waveform of A/F sensor.
f. Confirm that the display of "O2S B1 S2" changes between 0 V to 1V with the engine speed at 2,500 r.p.m.
2. INSPECT FUEL CUT OFF RPM
a. Increase the engine speed to at least 3,500 r.p.m.
b. Use a sound scope to check for injector operating noise.
c. Check that when the throttle lever is released, injector operation noise stops momentarily and then resumes.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.