Diagnosis & Repair

Access ECM harness connectors behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM section. Turn ignition on. Remove air intake duct. Disconnect sub-throttle actuator connector. See Fig 1. Measure voltage between ground and terminal No. 42 (Yellow/Red wire) at ECM "B" connector. See Figure.
Voltage should be .3-.8 volt (throttle closed) and 3.2-4.9 volts (throttle open). Measure voltage between ground and terminal No. 63 (Red/Black wire) at ECM "B" connector. Voltage should be 0-3 volts (throttle closed) and 9-14 volts (throttle open). If voltage is not as specified, go to next step. If voltage is as specified, no problem is detected at this time. Problem may be intermittent. Check wiring harness connectors for loose, damaged or corroded terminals. repair as necessary.
Disconnect SUB-TP sensor connector. See Fig 1. Measure resistance between terminals No. 1 (Brown wire) and No. 3 (Yellow/Red wire) at SUB-TP sensor. Resistance should be 200-800 ohms (throttle closed) and 2400-11,200 ohms (throttle open).
Measure resistance between terminals No. 1 (Brown wire) and No. 2 (Red/Black wire) at SUB-TP sensor. Resistance should be less than 500 ohms (throttle closed) and infinite (throttle open). If resistances are as specified, go to next step. If resistances are not as specified, adjust SUB-TP sensor. See ADJUSTMENTS article. If adjustment is okay, replace sensor.
Check for open or short in wiring harness between SUB-TP sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

Fig 1: Identifying Throttle Body Connectors (Models With TRAC)