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.
PINPOINT TEST DN: Motor Electronics Coolant Temperature (MECT) Sensor : Introduction
Do not disconnect, disable, or touch the high voltage cables, components, or wiring during the module reprogramming procedure because high voltage is present. The high voltage warning labels containing the high voltage symbol are located on each high voltage component. High voltage cables and wiring are orange in color. Failure to follow these instructions may result in personal injury or death.
Appropriate repair methods and procedures are essential for the safe, reliable operation of all motor vehicles, as well as the personal safety of the individual doing the work. This article provides general directions for repairing vehicles with tested, effective techniques. Following them helps to establish reliability. There are numerous variations in procedures, techniques, tools, and parts for repairing vehicles, as well as in the skill of the individual doing the work. This article cannot possibly anticipate all such variations and provide advice or cautions as to each. Accordingly, anyone who departs from the instructions provided in this article must first establish that they compromise neither their personal safety nor the vehicle integrity by their choice of methods, tools, or parts.
This pinpoint test is intended to diagnose the following:
- MECT (12B579)
- harness circuits: MECT, VREF, and SIGRTN
- powertrain control module (PCM) (12A650)
Voltage values calculated for VREF = 5 volts. These values can vary by 15% due to sensor and VREF variations.
| Temperature | Temperature Sensor Values | ||
|---|---|---|---|
| °C | °F | Voltage | Resistance (K ohms) |
| 120 | 248 | 0.28 | 1.18 |
| 110 | 230 | 0.36 | 1.55 |
| 100 | 212 | 0.47 | 2.07 |
| 90 | 194 | 0.61 | 2.80 |
| 80 | 176 | 0.80 | 3.84 |
| 70 | 158 | 1.05 | 5.37 |
| 60 | 140 | 1.37 | 7.70 |
| 50 | 122 | 1.77 | 10.97 |
| 40 | 104 | 2.23 | 16.15 |
| 30 | 86 | 2.74 | 24.27 |
| 20 | 68 | 3.26 | 37.30 |
| 10 | 50 | 3.73 | 58.75 |
| 0 | 32 | 4.14 | 95.85 |
| -10 | 14 | 4.45 | 160.31 |
| Pin | Circuit |
|---|---|
| 2 | SIGRTN-C (Signal Return Body/Cowl Connector) |
| 1 | MECT (Motor Electronics Coolant Temperature) |
| Pin | Circuit |
|---|---|
| B40 | VREF (Reference Voltage) |
| B41 | SIGRTN-C (Signal Return Body/Cowl Connector) |
| T3 | MECT (Motor Electronics Coolant Temperature) |
NO RELATED
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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.