Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition off. Remove cooling fan relays No. 2 and 3. See Fig 1. Start engine and let it idle. Turn A/C switch and blower fan switch to ON position. If cooling fans operate at low speed, go to next step. If cooling fans do not operate at low speed, go to PROCEDURE "A" .
- Turn ignition off. Install cooling fan relays No. 2 and 3. Turn A/C and blower off. Disconnect ECT sensor harness connector. See Figure. Connect a 150 ohm resistor between ECT sensor harness connector terminals. Start engine. If cooling fans operate at high speed, go to next step. If cooling fans do not operate at high speed, go to PROCEDURE "B" .
- Pressure test cooling system and radiator cap. Check thermostat operation. Radiator cap relief pressure should be 9-14 psi (0.63-0.98 kg/cm2 ). Thermostat opening temperature should be 180°F (82°C). Replace thermostat as necessary and retest system. If thermostat 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 SPECIFICATIONS . If resistance is not as specified, replace ECT sensor and retest system. If resistance is as specified, check for other possible causes of engine overheating and repair as necessary, then retest system.
ECT SENSOR RESISTANCE SPECIFICATIONS
| Temperature - °F (°C) | (1) Ohms | ||
|---|---|---|---|
| 14 (-10) | 7000-11,400 | ||
| 68 (20) | 2100-2900 | ||
| 122 (50) | 680-1000 | ||
| 194 (90) | 236-260 | ||
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