Saturn Coupes/Sedans/Wagons 1991-1998 Repair Guide

Coolant Temperature Sender

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On 1991-95 Saturn models, a coolant temperature sender, as well as a coolant temperature sensor, are used. Be careful not to confuse the single-wire coolant temperature sender used by the instrument cluster temperature gauge with the 2-wire sensor used by the PCM. On 1996-98 Saturn models, only one 2-wire sensor is used to perform both functions. For information on the Coolant Temperature Sensor, refer to Emission Controls .

TESTING



See Figures 1 and 2

  1. Remove the temperature sender from the engine.
  2.  
  3. Position the coolant temperature sender in such a way that the metal shaft (opposite end from the electrical connector) is situated in a container of water. Make sure that the electrical connector is not submerged and that only the tip of the sending unit' body is in the water.
  4.  
  5. Heat the container of water at a medium rate. While the water is warming, continue to measure the resistance of the terminal and the metal body of the sender:
    1. As the water warms up, the resistance exhibited by the ohmmeter goes down in a steady manner: the temperature sender is good.
    2.  
    3. As the water warms up, the resistance does not change or changes in erratic jumps: the sender is bad; replace it with a new one.
    4.  

  6.  
  7. Install the good unit or a new coolant temperature sender into the engine, then connect the negative battery cable.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Schematic for the coolant temperature sender circuit



Click image to see an enlarged view

Fig. Fig. 2: Sender resistance chart for the coolant temperature sender

REMOVAL & INSTALLATION



See Figure 3

The sender is threaded into the coolant passage at the rear of the cylinder head.

  1. Turn the ignition to the OFF position.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Position a clean container under the engine or radiator plug, and drain the engine coolant to a level below the sender.
  6.  
  7. Using your hand, a pair of pliers, or with the aid of a small prying tool, gently squeeze the sides of the sender's electrical connector, then remove the connector from the sender. Do not pull on the wire.
  8.  
  9. Using an appropriate sized deep well socket, remove the sender from the engine.
  10.  

To install:
  1. Apply a coat of Loctite® 242 or an equivalent threadlock to the coolant temperature sender threads, then install the sender and tighten to 71 inch lbs. (8 Nm).
  2.  
  3. Attach the sender's electrical connector. Push in until a click is heard and pull back slightly to confirm a positive engagement.
  4.  
  5. Connect the negative battery cable.
  6.  
  7. Refill the engine cooling system.
  8.  



Click image to see an enlarged view

Fig. Fig. 3: Location of the coolant temperature sender (which feeds the coolant temperature gauge)

 
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