Chrysler Neon 1995-1999 Repair Guide

Coolant Temperature Sensor

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OPERATION



See Figures 1 and 2

The PCM determines engine coolant temperature from the coolant temperature sensor. The combination coolant temperature sensor has two elements. One supplies a coolant temperature signal to the PCM, and the other element provides a coolant temperature signal to the instrument panel gauge cluster. As coolant temperature changes, the coolant temperature sensor's resistance changes, resulting in a different input voltage to the PCM and gauge. When the air is cold, the PCM provides a slightly richer air/fuel ratio and higher idle speed until the proper normal operating temperature is reached.



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Fig. Fig. 1: On SOHC engines, the coolant temperature sensor is threaded into the rear of the cylinder head, next to the camshaft position sensor



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Fig. Fig. 2: On DOHC engines, the coolant temperature sensor is threaded into the intake manifold, next to the thermostat housing

TESTING



See Figures 3 and 4

  1. Visually check the connector, making sure it is attached properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. With the ignition OFF , detach the electrical connector from the coolant temperature sensor.
  4.  
  5. Connect a digital ohmmeter to terminals A and B (shown in the accompanying figure). The ohmmeter should read as follows:
  6.  



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Fig. Fig. 3: Coolant temperature sensor terminal identification

  1. With the engine and sensor at normal operating temperature, about 200°F, the DVOM should read about 700-1,000 ohms.
  2.  
  3. With the engine and sensor at room temperature, about 70°F, the DVOM should read about 7,000-13,000 ohms.
  4.  



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Fig. Fig. 4: Attach an ohmmeter to the ECT sensor and measure the resistance

REMOVAL & INSTALLATION



See Figures 3 and 4

New sensors have sealant already applied to the threads.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the coolant into a suitable container, until it is at a level below the coolant temperature sensor.
  4.  
  5. Detach the coolant temperature sensor electrical connector.
  6.  
  7. Use a suitable wrench or ratchet, as applicable, to loosen and remove the coolant temperature sensor.
  8.  

To install:
  1. Install the coolant sensor and tighten to 60 inch lbs. (7 Nm) for 1995 vehicles or to 13.5 ft. lbs. (18 Nm) for 1996-99 vehicles.
  2.  
  3. Attach the electrical connector to the coolant temperature sensor.
  4.  
  5. Connect the negative battery cable. Fill the cooling system with the proper type and quantity of coolant.
  6.  

 
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