| CAUTION | Cooling system is under pressure. Danger of scalding when opening! |
Note. Use only gold-plated terminals when servicing terminals in the electrical harness connector of Engine Coolant Temperature (ECT) Sensor G62.
Special tools, testers and auxiliary items required
- Multimeter.
- Jumper wire.
- Wiring diagram.
Test requirements
- The Motronic Engine Control Module (ECM) J220 fuses OK.
- Battery voltage at least 12.5 volts.
- All electrical consumers such as, lights and rear window defroster, switched off.
- Vehicles with automatic transmission, shift selector lever into position "P" or "N".
- A/C switched off.
- Ground (GND) connections between engine/transmission/chassis OK.
- Ignition switched off.
- Engine cold.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to --> «General Diagnosis»(ref-276276-S40851803372008010300000) .
Start diagnosis
- Connect the scan tool.
- Switch the ignition on.
- Using the scan tool, check the coolant temperature
| Diagnostic text | Specified value | |||
|---|---|---|---|---|
| Coolant temperature | Approx. coolant temperature | |||
If the specified value is not obtained
- Continue test according to the following table
| Indicated | Cause | Test |
|---|---|---|
| Approx. -40.0°C | Open circuit or short circuit to (B+) | TESTING IF DISPLAY IS APPROX. - 40.0°C |
| Approx. 140.0°C | Short circuit to Ground (GND) | TESTING IF DISPLAY APPROX. 140.0°C |
If the specified value was obtained
- Start the engine and let it run at idle.
The temperature value must increase uniformly in increments of 1.0°C.
If the engine shows problems in certain temperature ranges and if the temperature does not climb uniformly, the temperature signal is intermittent.
- Replace the Engine Coolant Temperature (ECT) Sensor G62. Refer to --> «19 ENGINE - COOLING SYSTEM»(ref-276269-S03261728742008010300000) .
Checking internal resistance
Scheme 32
- Disconnect the Engine Coolant Temperature (ECT) Sensor G62 electrical harness connector - arrow -.
Scheme 33
- Using a multimeter , check the Engine Coolant Temperature (ECT) Sensor G62 terminals 1 to 2 for resistance.
Use the chart below for the specified values
- Area A: Resistance values 0 to 50°C.
- Area B: Resistance values 50 to 100°C.
Scheme 34
Specified values
- Range A, 30°C equals a resistance of 1.5 to 2.0 kohms
- Range B, 80°C equals a resistance of 275 to 375ohms
If any of the specified values was not obtained
- Replace the Engine Coolant Temperature (ECT) Sensor G62. Refer to --> «19 ENGINE - COOLING SYSTEM»(ref-276269-S03261728742008010300000) .