Diagnosis & Repair
- If using as oscilloscope, go to next step. If using Lexus scan tool, connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Using scan tool, monitor magnetic clutch current value. If magnetic clutch current is .8-1.0 amp, go to step 3. If magnetic clutch current is not .8-1.0 amp, go to step 5.
- Backprobing, connect oscilloscope between terminals No. 19 (Green/Black wire) and No. 20 (Green/Yellow wire) at ECM E15 connector. Start engine and allow it to idle. Waveform should be as illustrated. See Fig 1. If waveform is as illustrated, go to next step. If waveform is not as illustrated, go to step 5.
- Disconnect throttle control motor and magnetic clutch connector. Using an ohmmeter, measure resistance between throttle control motor connector terminals No. 3 (Green/Yellow wire) and No. 4 (Green/Black wire). See Figure. Resistance should be 4.2-5.2 ohms at 68°F (20°C). If resistance is at specified, go to next step. If resistance is not as specified, replace throttle control motor.
- Check for open or short circuit in wiring harness and connector between magnetic clutch and ECM. See appropriate wiring diagram in
WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, go to next step.
- Clear trouble codes. See
CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article. Turn ignition on. Start engine. Turn ignition off for 3 seconds. Turn ignition on. Retrieve trouble codes. See
RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - INTRODUCTION article. If DTC P1126 is not displayed, replace ECM and retest. If DTC P1126 is displayed, replace throttle control motor and retest.
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