Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA2000TACOMA BASE, 2D PICKUP, 2.4 L, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 4-CYLINDERDIAGNOSTIC TESTSDTC P0115: ENGINE COOLANT TEMPERATURE (ECT) SENSOR CIRCUITDIAGNOSIS & REPAIR
2000 Toyota Tacoma Base, 2D Pickup, 2.4 L, Standard
Diagnosis & Repair
2000 Toyota Tacoma Base, 2D Pickup, 2.4 L, StandardSECTION Diagnosis & Repair
- 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.
- Turn ignition off. Disconnect ECT sensor harness connector (2-pin harness connector with Green/Red wire and Brown/Black 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.
- Turn ignition off. Remove jumper wire. Access ECM behind glove box. On models with California emissions, connect a jumper wire by backprobing between terminals No. 12 (Green/Red wire) and No. 18 (Brown/Black wire) at ECM harness connector E7. See Figure. On models without California emissions, connect a jumper wire by backprobing between terminals No. 4 (Green/Red wire) and No. 9 (Brown/Black wire) at ECM harness connector E7. See Figure. On all models, temperature displayed on scan tool should be 284°F (140°C) or more. If temperature displayed is as specified, repair open in Green/Red wire and/or Brown/Black wire between ECT sensor and ECM. See 2.4L and 2.7L in SYSTEM WIRING DIAGRAMS article. If temperature displayed is not as specified, replace ECM.
- Turn ignition off. Disconnect ECT sensor harness connector (2-pin harness connector with Green/Red wire and Brown/Black wire). 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.
- Turn ignition off. Access ECM behind glove box. Disconnect ECM harness connector E7. See Figure or Figure . Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Green/Red wire between ECT sensor and ECM. See 2.4L and 2.7L in SYSTEM WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.