Pinpoint Tests DN: Motor Electronics Coolant Temperature (MECT) Sensor: Introduction
WARNING:
TO PREVENT THE RISK OF HIGH-VOLTAGE SHOCK, ALWAYS FOLLOW PRECISELY ALL WARNINGS AND SERVICE INSTRUCTIONS, INCLUDING INSTRUCTIONS TO DEPOWER THE SYSTEM. THE HIGH-VOLTAGE HYBRID SYSTEM UTILIZES APPROXIMATELY 300 VOLTS DC, PROVIDED THROUGH HIGH-VOLTAGE CABLES TO ITS COMPONENTS AND MODULES. THE HIGH-VOLTAGE CABLES AND WIRING ARE IDENTIFIED BY ORANGE HARNESS TAPE OR ORANGE WIRE COVERING. ALL HIGH-VOLTAGE COMPONENTS ARE MARKED WITH HIGH-VOLTAGE WARNING LABELS WITH A HIGH-VOLTAGE SYMBOL. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN SERIOUS PERSONAL INJURY OR DEATH.
NOTE:
Carefully check the motor electronics cooling system integrity. Over-temperature diagnostic trouble codes (DTCs) can be stored as a result of extreme driving conditions. Under normal operating conditions, the motor electronics coolant temperature should not exceed 65°C (150°F) and maintain a temperature of approximately 11°C (20°F) over ambient temperature during a steady cruise above 65 km/h (40mph).
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 SENSOR VOLTAGE AND RESISTANCE SPECIFICATIONS
| 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 |