Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition off. Disconnect ECT sensor harness connector. See Fig 1. Turn ignition on. Measure voltage between ground and ECT sensor harness connector terminal No. 2 (Light Green/Red wire). If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, repair open or short in Light Green/Red wire between ECT and ECM, then retest system.
- Turn ignition off. Check continuity between ground and ECT sensor harness connector terminal No. 1 (Black/Yellow wire). Continuity should exist. Also, check circuit for short to voltage. See WIRING DIAGRAMS article. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
- Remove ECT sensor and place in heated water. Measure resistance between ECT sensor terminals, with water at specified temperatures. See ECT SENSOR RESISTANCE table. If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor and retest system.
- If DTC P0115 is present, go to next step. If DTC P0125 is present, allow engine to cool until coolant temperature is less than 158°F (70°C). Start engine. Check thermostat operation. If thermostat is operating properly, go to next step. If thermostat is malfunctioning, replace thermostat and retest system.
- No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
ECT SENSOR RESISTANCE
| Temperature - °F (°C) | (1) Ohms | ||
|---|---|---|---|
| 68 (20) | 2100-2900 | ||
| 122 (50) | 680-1000 | ||
| 194 (90) | 236-260 | ||
|
|||