Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
- Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Waveform pattern should be checked for throttle control motor M+ and M- circuits at ECM. Connect oscilloscope between terminal No. 17 (Brown wire) at ECM electrical connector E6 and No. 7 (White wire; M- circuit) or No. 8 (Red wire; M+ circuit) at ECM electrical connector E5. This is the E1, M- and M+ terminals on ECM. For ECM electrical connector terminal identification, see Figure. Start engine and allow engine to idle. Note M- and M+ waveform pattern with engine idling. Ensure M- and M+ waveform patterns are properly displayed. See Fig 1. Ensure engine is idling when checking waveform pattern, as waveform pattern will change with throttle opening. If any waveform pattern is not as shown, shut engine off. Go to next step. If both waveform patterns are as shown, shut engine off. Replace ECM.
- Disconnect electrical connector at throttle control motor located on side of throttle body. See Fig 2. Using ohmmeter, check resistance between terminals No. 1 and 2 on electrical connector on throttle control motor. See Fig 2. Resistance should be .3-100.0 ohms at 68°F (20°C). If resistance is within specification, go to next step. If resistance is not within specification, replace throttle control motor. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
- Check for open and short in White and Red wires and electrical connectors between throttle control motor and ECM. See WIRING DIAGRAMS
article. If wiring harness and electrical connectors are okay, replace ECM. If wiring harness or electrical connector is defective, repair as necessary.
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