Mitsubishi Eclipse 1990-1998 Repair Guide

Engine Coolant Temperature

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TESTING



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.

Gauge Check

See Figures 1 and 2

  1. Detach the engine coolant gauge sensor electrical connector.
  2.  
  3. Connect a suitable test light (12V-3.4W) between the harness side connector and the ground.
  4.  
  5. Turn the ignition switch to the ON position.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Location of the engine coolant temperature gauge unit connectors-1990-94 vehicles



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Fig. Fig. 2: Engine coolant temperature gauge unit connector locations-1995-98 vehicles

  1. Check the condition of the test light and gauge as follows:
    1. If all components are operating properly, the test light should illuminate and the gauge needle should move.
    2.  
    3. If the test light is illuminates and the gauge needle does not moving, replace the coolant temperature gauge.
    4.  
    5. If the test light is illuminated and the gauge needle, check the fuse for a broken wire, or resistance between the gauge terminals
    6.  
    7. If the test light is not illuminated and the gauge is not moving, check, then replace the wiring harness, if necessary.
    8.  

  2.  

Sender Check

See Figure 3

  1. Drain the engine coolant to a level below the coolant temperature sensor.
  2.  
  3. Disconnect the sensor wiring harness and remove the coolant temperature sensor.
  4.  
  5. Place the sensor tip in a pan of warm water. Use a thermometer to measure the water temperature.
  6.  
  7. Measure the resistance across the sensor terminals while the sensor is in the water.
  8.  



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Fig. Fig. 3: Place the sensor in water and measure the resistance

  1. 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.
     

  2.  

If the resistance is not approximately accurate for the temperature, the sensor must be replaced.

REMOVAL & INSTALLATION



See Figures 4 and 5

  1. Disconnect the negative battery cable.
  2.  
  3. Position a suitable drain pan under the radiator.
  4.  
  5. Drain the engine coolant a level below the coolant temperature sensor.
  6.  
  7. Disconnect the sensor wiring harness, then remove the coolant temperature sensor from the engine.
  8.  



Click image to see an enlarged view

Fig. Fig. 4: Typical locations of the engine coolant temperature gauge unit and related components

To install:
  1. Coat the sensor threads with a suitable thread sealant.
  2.  



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Fig. Fig. 5: Before installing the sensor, coat the threads with a suitable sealant

  1. Install the engine coolant temperature gauge sensor into the bore in the engine and tighten to 7-8 ft. lbs. (10-12 Nm).
  2.  
  3. Attach the electrical harness connector to the sensor.
  4.  
  5. Fill the cooling system to the proper level. Connect the negative battery cable.
  6.  

 
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