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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 97 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0115: Engine Coolant Temperature (ECT) Sensor Circuit >> Diagnosis & Repair

Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Turn scan tool on. Using scan tool, monitor ECT sensor temperature. If temperature displayed is same as actual coolant temperature, check component and ECM connections. Problem is intermittent If temperature displayed is 284°F (140°C), go to step  4. If temperature displayed is -40°F (-40°C), go to next step.
  2. Turn ignition off. Disconnect ECT sensor harness connector. Connect a fused jumper wire between terminals No. 2 (Green/White wire) and No. 1 (Brown wire) at ECT sensor harness connector. See Fig 1. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed is 284°F (140°C) or more, ensure ECT connector is okay. If connector is okay, replace ECT sensor and retest system. If temperature displayed is less than 284°F (140°C), go to next step.
    Fig 1: Connecting Fused Jumper Wire At ECT Circuit
    G00165044Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Turn ignition off. Remove fused jumper wire. Access ECM behind glove box. Backprobing connector, connect a fused jumper wire between terminals No. 14 (Green/White wire) and No. 18 (Brown wire) at ECM E8 connector. See Figure and Fig 2 . If temperature displayed on scan tool is 284°F (140°C) or more, check and repair open in Green/White wire between ECT sensor harness connector and ECM E8 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest system.
    Fig 2: Connecting Fused Jumper Wire At ECM
    G00165043Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. Turn ignition off. Disconnect ECT sensor harness connector. See Fig 3. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor and retest system. If temperature displayed is not -40°F (-40°C), turn ignition off and go to next step.
    Fig 3: Checking ECT With Sensor Disconnected
    G00165045Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  5. Access ECM behind glove box. Disconnect ECM E8 connector. See Fig 4. Turn ignition on. If temperature displayed is -40°F (-40°C), locate and repair short circuit in wiring harness between ECT sensor and ECM E8 connector. See Figure. If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest system.
    Fig 4: Disconnecting ECM E8 Connector
    G00165046Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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