DTC P0118 - ENGINE COOLANT TEMPERATURE SENSOR HIGH VOLTAGE INPUT Isuzu Oasis I

1. Turn ignition on. Check Engine Coolant Temperature (ECT) sensor using OBD-II scan tool. If -4°F (-20°C) or less, or 5.0 volts is indicated, go to next step. If -4°F (-20°C) or less, or 5.0 volts is not indicated, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at ECT sensor and PCM connectors. See WIRING DIAGRAMS article.
2. Disconnect ECT sensor 2-pin connector. Install a fused jumper wire between ECT sensor harness connector terminals. Check ECT sensor using OBD-II scan tool. If -4°F (-20°C) or less, or 5.0 volts is indicated, go to next step. If -4°F (-20°C) or less, or 5.0 volts is not indicated, replace ECT sensor.
3. Turn ignition off. Connect a fused jumper wire between PCM 31-pin connector "C" terminal C18 (Green/Black wire) and terminal C26 (Red/White wire). Turn ignition on. Check ECT sensor using OBD-II scan tool. If -4°F (-20°C) or less, or 5.0 volts is not indicated, repair open in wire(s) between ECT sensor and PCM connector terminals. See WIRING DIAGRAMS article. If -4°F (-20°C) or less, or 5.0 volts is indicated, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.

Scheme 26

1. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral until radiator fan comes on. Turn ignition off. Turn ignition on. Using OBD-II scan tool, check throttle position. If about 10 percent with throttle fully closed and 90 percent with throttle fully opened is not indicated, go to next step. If about 10 percent with throttle fully closed and 90 percent with throttle fully opened is indicated, problem is intermittent. System is okay at this time. Check for poor connections or loose wires at TP sensor and PCM connectors. See WIRING DIAGRAMS article.
2. Turn ignition off. Disconnect TP sensor 3-pin connector. Turn ignition on. Measure voltage between TP sensor 3-pin harness connector terminal No. 1 (Green/Black wire) and terminal No. 3 (Yellow/Blue wire). see scheme 6 If about 5.0 volts does not exist, go to next step. If about 5.0 volts exists, go to step 4).
3. Using backprobe kit, measure voltage between PCM 31-pin connector "C" terminal C18 (Green/Black wire) and terminal C28 (Yellow/Blue wire). see scheme 3 If about 5.0 volts exists, repair open in Yellow/Blue wire between PCM connector and TP sensor. See WIRING DIAGRAMS article. If about 5.0 volts does not exist, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM.
4. Turn ignition off. Measure TP sensor resistance between sensor terminals No. 1 and 2 with throttle fully closed. (Scheme 26) If resistance is about 500-900 ohms, go to next step. If resistance is not about 500-900 ohms, replace throttle body (TP sensor cannot be serviced separately).
5. Measure TP sensor resistance between sensor terminals No. 2 and 3 with throttle fully closed. If resistance is about 4500 ohms, go to next step. If resistance is not about 4500 ohms, replace throttle body (TP sensor is not serviced separately).
6. Reconnect TP sensor connector. Turn ignition on. Using backprobe kit, measure voltage between PCM 31-pin connector "C" terminal C18 (Green/Black wire) and terminal C27 (Red/Black wire). see scheme 3 If voltage is about 0.5 volt with throttle fully closed and 4.5 volts with throttle fully open, substitute a known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If voltage is not as specified, repair short in Green/Black wire between PCM connector and TP sensor.