Air Fuel Ratio Compensation System (Es300)
WARNING: This page is about a different car, the 2002 Lexus RX 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
Measure voltage (backprobe) between ECM connector terminals. See Fig 1. For voltage specifications, see AIR FUEL RATIO COMPENSATION SYSTEM VOLTAGE SPECIFICATIONS table. Connect hand-held tester to DLC3. Select DATA MONITOR A/FS B1 S1. A/FS B2 S1 and O2S B1 S2 should display on monitor. Warm up A/F sensor with engine speed at 2500 PRM for about 2 minutes. Keep engine speed at 2500 RPM and confirm displays of A/FS B1 S1 and A/FS B2 S1 are as shown in illustration. Confirm display of O2S B1 S2 changes between 0-1 volt with engine speed at 2500 RPM. See Fig 2.
NOTE:
Illustration is different from real display. Only hand-held tester displays waveform of A/F sensor.
AIR FUEL RATIO COMPENSATION SYSTEM VOLTAGE SPECIFICATIONS
| Terminal | Condition | Voltage |
|---|---|---|
| AFR+ - E1 | Ignition Switch On | 3.3 |
| AFR- - E1 | Ignition Switch On | 3.0 |
| AFL+ - E1 | Ignition Switch On | 3.3 |
| AFL- - E1 | Ignition Switch On | 3.0 |