NOTE:
Before performing the following inspection, make sure to follow the procedure as indicated in the troubleshooting flowchart. (See HOW TO USE THIS MANUAL.)
1. Warm up the engine to normal operating temperature.
2. Using the M-MDS, monitor the following:
Vehicle speed (PID: VSS)
Engine speed (PID: RPM)
Rear HO2S voltage (PID: O2S12)
3. Drive the vehicle and decelerate the engine speed by releasing the accelerator pedal fully when the engine speed is 3,000 rpm or more.
4. Verify that the rear HO2S outputs a voltage of 0.6 V or more, one time or more, then verify that the rear HO2S voltage (PID: O2S12) is 0.3 V or less while decelerating as shown in the figure.
If not within the specification, inspect the rear HO2S for an open or short circuit. (See REAR HEATED OXYGEN SENSOR (HO2S) INSPECTION [LF].) Then if there is no malfunction in the wiring harness, replace the rear HO2S. (See REAR HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF].)
1. Disconnect the rear HO2S connector.
2. Measure the rear HO2S resistance between terminals C and D.
If not within the specification, replace the rear HO2S. (See REAR HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [LF].)
Rear HO2S heater resistance
2—50 ohms
1. Disconnect the PCM connector.
2. Disconnect the rear HO2S connector.
3. Inspect the following wiring harnesses for an open or short circuit. (Continuity inspection)
Open circuit
If there is no continuity, there is an open circuit. Repair or replace the wiring harness.
Rear HO2S terminal A and PCM terminal 2Q
Rear HO2S terminal B and PCM terminal 2BH
Rear HO2S terminal C and ignition relay
Rear HO2S terminal D and PCM terminal 2BE
Short circuit
If there is continuity in the following wiring harnesses, there is a short circuit. Repair or replace the wiring harness.
Rear HO2S terminal A and power supply
Rear HO2S terminal A and body ground
Rear HO2S terminal B and power supply
Rear HO2S terminal B and body ground
Rear HO2S terminal C and body ground
Rear HO2S terminal D and power supply
Rear HO2S terminal D and body ground