GM Bonneville/Eighty Eight/LeSabre 1986-1999

Coolant Temperature Sender

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OPERATION



The coolant temperature sender changes resistance as the coolant temperature increases and decreases.

TESTING



  1. Remove the temperature sender from the engine.
  2.  
  3. Position the water temperature sending unit in such a way that the metal shaft (opposite end from the electrical connectors) is situated in a pot of water. Make sure that the electrical connector is not submerged and that only the tip of the sending unit's body is in the water.
  4.  
  5. Heat the pot 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 sending unit:
    1. As the water warms up, the resistance exhibited by the ohmmeter goes down in a steady manner: the sending unit 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 or new sending unit into the engine, then connect the negative battery cable.
  8.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Drain the coolant to a level below the coolant temperature sender.
  4.  
  5. Unplug the sender electrical connector, then unscrew the sender. The sender can usually be found mounted in the engine block or threaded into the thermostat housing/outlet or radiator.
  6.  

To install:
  1. Install the sender in the vehicle and tighten securely.
  2.  
  3. Attach the sender electrical connector.
  4.  
  5. Refill the cooling system to the proper level with the proper type and amount of coolant.
  6.  
  7. Connect the negative battery cable.
  8.  

 
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