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Engine Coolant Temperature Gauge System Test

NOTE: If needle stays in cold position, circuit between instrument cluster and sending unit may be open. If needle stays in hot position, circuit may be shorted to ground.
  1. Check for continuity between hex portion of temperature gauge sending unit and engine block. If there is no continuity, repair poor ground between sending unit and engine block. If there is continuity, disconnect electrical connector from sending unit.
  2. Turn ignition on. Gauge should indicate cold. Connect a 3.4-watt light bulb between chassis ground and sending unit connector terminal. Gauge should indicate hot and light should come on. If gauge indicates as specified, replace sending unit.
  3. If gauge does not indicate as specified, turn ignition off. Disconnect connector "C" from instrument cluster. See Figure.
  4. Check circuit between sending unit and terminal No. 21 of disconnected instrument cluster connector. See Figure. If circuit is okay, check gauge resistance. See ENGINE COOLANT TEMPERATURE GAUGE RESISTANCE TEST  under COMPONENT TESTING. If gauge resistance is okay, replace circuit plate. See Figure.
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