Pinpoint Tests DL: Cylinder Head Temperature (CHT) 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 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.
This pinpoint test is intended to diagnose the following:
The PCM has a dual switching resistor circuit on the CHT input. A graph showing the temperature switching from the COLD END line to the HOT END line, with increasing temperature and back with decreasing temperature is included. Note the temperature to voltage overlap zone. Within this zone it is possible to have either a COLD END or HOT END voltage at the same temperature. For example, at 90°C (194°F) the voltage could read either 0.60 volt or 3.71 volts. Refer to the table for the temperature to voltage expected values.
CYLINDER HEAD TEMPERATURE SENSOR EXPECTED VALUES
| Temperature | CHT Sensor Values | |||
|---|---|---|---|---|
| °C | °F | COLD END (volts) | HOT END (volts) | Resistance (K ohms) |
| -40 | -40 | 4.89 | - | 965.808 |
| -30 | -22 | 4.81 | - | 513.019 |
| -20 | -4 | 4.67 | - | 283.664 |
| -10 | 14 | 4.45 | - | 162.584 |
| 0 | 32 | 4.14 | - | 96.255 |
| 10 | 50 | 3.73 | - | 59.175 |
| 20 | 68 | 3.26 | - | 37.387 |
| 30 | 86 | 2.74 | - | 24.215 |
| 40 | 104 | 2.23 | - | 16.043 |
| 50 | 122 | 1.76 | - | 10.85 |
| 60 | 140 | 1.36 | - | 7.487 |
| 70 | 158 | 1.04 | - | 5.268 |
| 80 | 176 | 0.79 | 3.99 | 3.775 |
| 85 | 185 | 0.69 | 3.86 | 3.215 |
| 90 | 194 | 0.60 | 3.71 | 2.75 |
| 95 | 203 | 0.53 | 3.56 | 2.361 |
| 100 | 212 | 0.46 | 3.41 | 2.034 |
| 110 | 230 | - | 3.07 | 1.523 |
| 120 | 248 | - | 2.74 | 1.155 |
| 130 | 266 | - | 2.41 | 0.8866 |
| 140 | 284 | - | 2.10 | 0.6891 |
| 150 | 302 | - | 1.81 | 0.5417 |
| 160 | 320 | - | 1.55 | 0.4301 |
| 170 | 338 | - | 1.33 | 0.3449 |
| 180 | 356 | - | 1.13 | 0.2791 |
| 190 | 374 | - | 0.96 | 0.2278 |
| 200 | 392 | - | 0.82 | 0.1875 |
| 210 | 410 | - | 0.70 | 0.155 |
| 220 | 428 | - | 0.60 | 0.130 |
| 230 | 446 | - | 0.51 | 0.109 |
| 240 | 464 | - | 0.44 | 0.092 |
| 250 | 482 | 0.35 | 0.078 | |
| 260 | 500 | 0.33 | 0.067 | |
Harness Side
| Circuit | Pin |
|---|---|
| CHT (Cylinder Head Temperature) | 1 |
| SIGRTN (Signal Return) | 2 |
Harness Side
| Circuit | Pin |
|---|---|
| CHT (Cylinder Head Temperature) | E15 |
| SIGRTN (Signal Return) | E3 |