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
AC Clutch: The parameter indicates On whenever the powertrain control module (PCM) energizes the A/C compressor clutch relay. Engaging the A/C compressor clutch relay will also engage the cooling fan at low speed.
AC Request Signal: This parameter indicates whether the A/C switch on the instrument panel (IP) has been selected.
ECT Sensor: The scan tool range is -40 to +140°C (-40 to +284°F). The engine coolant temperature (ECT) sensor is a thermistor which changes internal resistance as the temperature changes. When the sensor is cold, internal resistance high, the powertrain control module (PCM) monitors a high signal voltage and interprets the voltage 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.
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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.