The coolant temperature sensor is used to operate the temperature gauge.
Do not confuse this sensor with the other switches or sensors used to signal
the engine control unit or air conditioning regarding temperature of the coolant.
Usually, these other units are mounted near the coolant temperature sensor
used for engine control.
- Detach the engine coolant gauge sensor electrical connector.
- Connect a suitable test light (12V–3.4W) between the harness side
connector and the ground.
- Turn the ignition switch to the ON position.
| Fig. 1: Location of the engine coolant temperature
gauge unit connectors — 1990–94 vehicles
|
| Fig. 2: Engine coolant temperature gauge unit connector
locations — 1995–98 vehicles
|
- Check the condition of the test light and gauge as follows:
- If all components are operating properly, the test light should illuminate
and the gauge needle should move.
- If the test light is illuminates and the gauge needle does not moving,
replace the coolant temperature gauge.
- If the test light is illuminated and the gauge needle, check the fuse
for a broken wire, or resistance between the gauge terminals
- If the test light is not illuminated and the gauge is not moving,
check, then replace the wiring harness, if necessary.
- Drain the engine coolant to a level below the coolant temperature sensor.
- Disconnect the sensor wiring harness and remove the coolant temperature
sensor.
- Place the sensor tip in a pan of warm water. Use a thermometer to measure
the water temperature.
- Measure the resistance across the sensor terminals while the sensor is
in the water.
| Fig. 3: Place the sensor in water and measure the
resistance
|
- Note the ohm reading and compare to the following specifications:
- Water temperature of 68°F (20°C) — 2.21–2.69
kilo-ohms resistance
- Water temperature of 158°F (70°C) — 90.5–117.5
ohms resistance
- Water temperature of 176°F (80°C) — 264–328
ohms resistance.
If the resistance is not approximately accurate for the temperature,
the sensor must be replaced.
