Chrysler Full-Size Vans 1989-1998 Repair Guide

Coolant Temperature Sender

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TESTING



See Figure 1

A quick way to determine if the gauge, the so-called "idiot" light, or the sending unit is faulty, is to disconnect the sending unit electrical harness and ground it (if two-terminal, jumper between the terminals) with the ignition ON . If the gauge responds or the light illuminates, the sending unit may be faulty. Proceed with the following sending unit test.

  1. Disconnect the sending unit electrical harness.
  2.  
  3. Remove the radiator cap and place a mechanic-s thermometer in the coolant.
  4.  
  5. Using an ohmmeter, check the resistance between the sending unit terminals.
  6.  
  7. Resistance should be high with the engine coolant cold and low with the engine coolant hot.
  8.  

It is best to check resistance with the engine cool, then start the engine and watch the resistance change as the engine warms.

  1. If resistance does not drop as engine temperature rises, the sending unit is faulty.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: The temperature sender is located at the front of the engine, adjacent to the thermostat

REMOVAL & INSTALLATION



  1. Locate the coolant temperature sending unit on the engine.
  2.  
  3. Disconnect the sending unit electrical harness.
  4.  
  5. Drain the engine coolant below the level of the switch.
  6.  
  7. Unfasten and remove the sending unit from the engine.
  8.  

To install:
  1. Coat the new sending unit with Teflon tape or electrically conductive sealer.
  2.  
  3. Install the sending unit and tighten to 11-15 ft. lbs. (15-20 Nm).
  4.  
  5. Attach the sending unit-s electrical connector.
  6.  
  7. Replenish the necessary amount of coolant.
  8.  
  9. Start the engine, allow it to reach operating temperature and check for leaks.
  10.  
  11. Check for proper sending unit operation.
  12.  

 
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