GM Astro/Safari 1985-1996 Repair Guide

Coolant Temperature Sensor

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OPERATION

The coolant temperature sensor changes resistance as the coolant temperature increases and decreases. The sensor is located on the left side of the engine on both the V6 and I4 engines. On the V6 it is screwed into the head between the rear two exhaust ports. On the I4 engine, it is screwed into the rear of the head just in front of the lifting eye.

TESTING



  1. Turn the ignition switch to ON , but do not start the engine.
  2.  
  3. Disconnect the sensor lead at the sensor. Connect a test lamp to the lead; The lamp should glow. If not, check the wiring, fuses and connections.
  4.  
  5. Disconnect the test lamp and ground the connector. The gauge should read at the HOT mark.
  6.  
  7. Remove the connector from ground. The gauge should read at the COLD mark.
  8.  
  9. At 104°F (40°C) the resistance of the sensor should be 1365 ohms.
  10.  
  11. At 257°F (125°C) the resistance of the sensor should be 55 ohms.
  12.  

REMOVAL & INSTALLATION



See Figure 1

  1. Disconnect the negative battery cable and drain the engine coolant. Remove the engine cover.
  2.  
  3. Disconnect the sensor electrical lead and unscrew the sensor.
  4.  

To install:
  1. Install the sensor and tighten it to 17 ft. lbs. (23 Nm). Connect the electrical lead.
  2.  
  3. Connect the battery cable and fill the engine with coolant. Install the engine cover.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Coolant temperature and oil pressure senders-2.5L and 4.3L engines

 
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