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Coolant Temperature Gauge Inaccurate

  1. Disconnect negative battery cable. Remove instrument cluster. See INSTRUMENT CLUSTER under REMOVAL & INSTALLATION. Disconnect instrument cluster connectors C250 and C251. See Figure and Figure . Reconnect negative battery cable and turn ignition switch to RUN position. Check for battery voltage at cluster connector C250 terminal No. 16 (Red/Yellow wire). If battery voltage is present, go to next step. If battery voltage is not present, repair short or open in circuit No. 640 (Red/Yellow wire).
  2. Measure resistance between ground and instrument cluster connector C250 terminal No. 15 (Orange/Yellow wire). If resistance is less than one ohm, go to next step. If resistance is more than one ohm, repair open in circuit No. 563 (Orange/Yellow wire) or circuit No. 397 (Black/White wire) and retest system.
  3. Turn ignition off. Disconnect temperature sensor connector. Connect Instrument Gauge System Tester (014-R1063) to temperature sensor harness connector. Set tester at 300 ohms. Turn ignition on, wait 60 seconds and read gauge. If gauge reads cold, go to next step. If gauge does not read cold, go to step 5).
  4. Set tester to 18 ohms, wait 60 seconds and read gauge. If gauge reads hot, replace temperature sending unit and retest system. If gauge does not read hot, go to next step.
  5. Turn ignition off. Check resistance between cluster printed circuit connectors and temperature gauge. If resistance is less than 0.2 ohm through instrument cluster printed circuit, go to next step. If resistance is more than 0.2 ohm through instrument cluster printed circuit, repair or replace instrument cluster printed circuit and retest system. See PRINTED CIRCUIT under REMOVAL & INSTALLATION.
  6. Check resistance of Red/White wire between instrument cluster connector C250 terminal No. 15 and temperature sensor connector. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, check for corrosion and poor harness connections. Repair as required and retest system.
  7. Check resistance between ground and temperature sensor connector Yellow/Red wire. If resistance is less than 5 ohms, replace instrument cluster and retest system. If resistance is more than 5 ohms, replace temperature sender and retest system.
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