Coolant Temperature Sensor: Notes
- A 4-pole CTS is used for EZL ignition systems. It combines two sensors into one housing. Neither sensor is connected to housing for grounding purposes. One sensor is for EZL ignition system (terminals No. 1 and 3) and other sensor is for CIS-E fuel injection system (terminals No. 2 and 4). Both CTS sensors are internally identical so that harness connector can be attached in any position to CTS.
- Unplug CTS harness connector. Using ohmmeter, check resistance value across diagonally opposite terminals of CTS. Refer to appropriate COOLANT TEMPERATURE SENSOR SPECIFICATIONS
table for resistance and voltage specification at engine coolant temperature. See Fig 1
. If resistance or voltage values are not to specification, replace coolant temperature sensor.
COOLANT TEMPERATURE SENSOR SPECIFICATIONS (3.0L)
| Temperature °F (°C) |
Ohms |
Volts |
| -4 (-20) |
15,700 |
5.1-5.6 |
| 14 (-10) |
10,000 |
4.5-5.1 |
| 32 (0) |
5900 |
4.1-4.5 |
| 50 (10) |
3700 |
3.8-4.1 |
| 68 (20) |
2500 |
3.4-3.8 |
| 86 (30) |
1700 |
2.9-3.3 |
| 104 (40) |
1170 |
2.5-2.9 |
| 122 (50) |
830 |
2.1-2.5 |
| 140 (60) |
600 |
1.7-2.1 |
| 158 (70) |
435 |
1.4-1.7 |
| 176 (80) |
325 |
1.1-1.3 |
| 194 (90) |
245 |
.9-1.1 |
| 212 (100) |
185 |
.7-.9 |
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.