Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
- If not using Lexus scan tool, go to step 3. If using Lexus scan tool, go to next step.
- Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Using scan tool, read magnetic clutch current value. If reading is .8-1.0 amp, go to step 4. If reading is not .8-1.0 amp, go to step 6.
- Turn ignition off. Access ECM behind glove box. Connect an oscilloscope by backprobing between terminals No. 19 (Blue wire) and No. 29 (Green wire) at ECM harness connector E6. See Figure. Start engine and allow it to idle. Observe waveform. See Fig 1. If waveform is not okay, go to next step. If waveform is okay, go to step 6.
- Disconnect throttle control motor Gray 4-pin harness connector. Measure resistance between terminals No. 3 (Green wire terminal) and No. 4 (Blue wire terminal) at throttle control motor (component side). Resistance should be 4.2-5.2 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace throttle control motor.
- Check for open or short in wiring between throttle control motor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
- Clear DTC. Start engine. Turn ignition off and wait 3 seconds. Turn ignition on and check for DTCs. If DTC P1126 is not present, replace ECM. If DTC P1126 is present, replace throttle control motor.