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.
Scan Tool Data Definitions
Coolant Level: The scan tool displays OK or Low. This parameter indicates the level of the coolant in the surge tank.
ECT Sensor: The scan tool displays -40°C to +150°C (-40°F to +302°F). The Engine Coolant Temperature (ECT) sensor is mounted in the coolant stream. The Powertrain Control Module (PCM) applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as the temperature changes. When the sensor is cold (internal resistance high), The PCM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.
FC Relay 1 Circuit Status: The scan tool displays OK or Fault. This parameter indicates the state of the driver circuit for this device.
FC Relay 1 Command: The scan tool displays On or Off. The PCM is commanding Fan Control Relay 1 On when the scan tool indicates On. When the PCM commands the Fan Control Relay 1 On, both fans are enabled at low speed.
FC Relay 2 and 3 Circuit: The scan tool displays OK or Fault. This parameter indicates the state of the driver circuit for this device.
FC Relay 2 and 3 Command: The scan tool displays On or Off. The PCM is commanding all three fan control relays On when the scan tool indicates On. When all fan control relays are activated, both cooling fans are enabled at high speed.
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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.