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Home >> Toyota >> 1999 >> Land Cruiser >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0115: Engine Coolant Temperature (ECT) Sensor Circuit >> Diagnosis & Repair

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is same as actual coolant temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step  4.
  2. Turn ignition off. Disconnect ECT sensor harness connector (2-pin harness connector with Green/Black wire and Brown/White wire). Using a jumper wire, connect ECT sensor harness connector terminals. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is less than 284°F (140°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, replace ECT sensor.
  3. Turn ignition off. Remove jumper wire. Access ECM behind glove box. Using a jumper wire, backprobe between terminals No. 18 (Brown/White wire) and No. 14 (Green/Black wire) at ECM harness connector E6. See Figure. If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Green/Black wire and/or Brown/White wire between ECT sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If temperature displayed on scan tool is less than 284°F (140°C), replace ECM.
  4. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor. If temperature displayed on scan tool is not -40°F (-40°C), go to next step.
  5. Turn ignition off. Access ECM behind glove box. Disconnect ECM harness connector E6. See Figure. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Green/Black wire between ECT sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.
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