Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

NOTE:
To perform a complete test of Coolant Temperature sensor and its circuitry, refer to appropriate Diagnostics Chart. To test the sensor only, refer to the following:

1. Disconnect wire harness connector from coolant temperature sensor.

NOTE: Engines with air conditioning: when removing the connector from sensor, do not pull directly on wiring harness. Fabricate an L shaped hook tool from a coat hanger (approximately eight inches long). Place the hook part of tool under the connector for removal. The connector is snapped onto the sensor. It is not equipped with a lock type tab.

2. Test the resistance of the sensor with a high input impedance (digital) volt-ohmmeter. The resistance (as measured across the sensor terminals) should be less than 1000 ohms with the engine warm. Refer to the Coolant Temperature sensor/Charge Air Temperature sensor resistance chart. Replace the sensor if it is not within the range of resistance specified in the chart.

3. Test continuity of the wire harness. Do this between the Engine Controller wire harness connector terminal 2 and the sensor connector terminal. Also test continuity of wire harness terminal 4 to the sensor connector terminal. Repair the wire harness if an open circuit is indicated.

4. After tests are completed, connect electrical connector to sensor. The sensor connector is symmetrical (not indexed). It can be installed to the sensor in either direction.



TEMPERATURE RESISTANCE (OHMS)

°C °F MIN MAX


-40 -4O 291,490 381,710

-20 -4 85,850 108,390

-10 14 49,250 61,430

0 32 29,330 35,990

10 50 17,990 21,810

20 68 11,370 13,610

25 77 9,120 10,880

30 86 7,370 8,750

40 104 4,900 5,750

50 122 3,330 3,880

60 14O 2,310 2,670

70 158 1,630 1,870

80 176 1,170 1,340

90 194 860 970

100 212 640 720

110 230 480 540

120 248 370 410