Diagnosis & Repair

Turn ignition off. Access ECM on driver's side of firewall behind driver's seat, luggage compartment lids and partition board. See Figure. Connect an oscilloscope by backprobing between terminal No. 17 (Brown wire) at ECM harness connector E4 and terminal No. 19 (Red wire; circuit M+) or No. 29 (Green wire; circuit M-) at ECM harness connector E5. Start engine and allow to engine to idle. Observe waveform. See Fig 1 and Fig 2 . If waveform is not okay, go to next step. If waveform is okay, replace ECM.
Disconnect throttle control motor Gray, 4-pin harness connector. Measure resistance between terminals No. 1 (Red wire) and No. 2 (Green wire) at throttle control motor (component side). Resistance should be .3-100.0 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, replace ECM.

Fig 1: Identifying Correct Throttle Control Motor M+ Signal Waveform

Fig 2: Identifying Correct Throttle Control Motor M- Signal Waveform