Diagnosis & Repair
WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
- Connect scan tool to Data Link Connector (DLC) No. 3. See Fig 2. Disconnect EA1 connector. EA1 connector is a wire-to-wire connector located in engine compartment, near idle air control valve. Connector is a Dark Gray 4-pin connector.
- Connect a fused jumper wire between terminal No. 1 of male connector to terminal No. 2 of female connector. Connect another fused jumper wire between terminal No. 2 of male connector to terminal No. 1 of female connector. See Fig 2. Turn ignition on. Turn scan tool on. Start and warm engine to normal operating temperature.
- Snap accelerate engine 3 times to 4000 RPM. If using oscilloscope, with engine racing (4000 RPM), check the wave between terminals KNKR, KNKL of the ECM connector and the body ground. Spread the time on the horizontal axis, and confirm that period of the wave is as shown in illustration. See Fig 1. Normal mode vibration frequency of knock sensor is 7.1 kHz. If normal mode vibration frequency is not 7.1 kHz, the sensor is malfunctioning. Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If same code is repeated as before, go to next step. If code has changed, go to step 5.
- Check for open or short circuit(s) between EA1 connector and ECM harness connector. See ENGINE PERFORMANCE in WIRING DIAGRAMS article in ELECTRICAL. Repair as necessary. If circuits are okay, replace ECM and retest system.
- Check for open or short circuit(s) between EA1 connector and suspect knock sensor. If DTC P0325 has changed to DTC P0330, check knock sensor circuit on right bank. If DTC P0330 changed to DTC P0325, check knock sensor circuit on left bank. Repair as necessary. If harness is okay, replace knock sensor.