Contents: Crankshaft speed sensor ↡ Electronic control unit (ECU) ↡ Coolant temperature sensor ↡ Throttle Position Sensor ↡
Note: Disconnecting/removing the ignition control system sensors may cause errors to be recorded in the memory of the electronic control unit. Certain errors cause the system to go into "protective" mode, which affects the vehicle's ability to drive. Therefore, after completing repair work, it is recommended to contact a Mercedes-Benz service station and "erase" these errors using the first three options.
Crankshaft speed sensor
Removal
1. Disconnect the negative battery terminal.
2. Disconnect the sensor wire from the harness at the connector, which is located in the engine compartment behind the battery.
3. Unscrew the mounting bolt and remove the sensor from the clutch housing. Remove the metal bushing where it is installed.
Installation
4. Installation is carried out in the reverse order. Where provided, before inserting the sensor into the housing, make sure that the bushing is installed.
Electronic control unit (ECU)
Removal
5. The ignition system control unit is located on the left side of the engine compartment, on top of the inner wheel arch (see fig. 6.5).
Original source of information [MERCEDESMAN]
Fig. 6.5. Location of the electronic control unit
6. Disconnect the negative battery terminal.
7. Disconnect the connectors from the crankshaft and knock sensor sockets. Also disconnect the two multi-pin connectors, marking each one for proper reinstallation.
8. Disconnect the manifold vacuum hose from the fitting on top of the control unit. Plug the fitting to prevent dirt from getting into it.
9. Loosen the mounting nuts and remove the control unit from the engine compartment.
Note: The bottom of the control unit is coated with heat-conducting paste to improve cooling - try not to stain the surrounding parts with paste. Do not remove the protective layer.
Installation
10. Installation is carried out in reverse order. If the contact paste layer is dirty or has hardened over time, purchase the required amount of paste from your Mercedes-Benz dealer and apply it again. Check that the protective layer is applied correctly.
Coolant temperature sensor
11. Where provided, the ignition system and fuel injection system share a common coolant temperature sensor - refer to the information provided in the relevant section Chapters 4B (see fig. 6.11).
Fig. 6.11. Coolant temperature sensor
Throttle Position Sensor
12. The ignition system shares one common sensor with the fuel system - throttle position sensor - refer to the information provided in the relevant section Chapters 4B.
TDC position sensor
13. The TDC sensor is located on a bracket above the crankshaft vibration damper at the front of the engine. Installing the sensor with the bracket on the vibration damper critically affects the operation of the ignition system and requires complex installation steps. For this reason, it is recommended that this work be performed at a service station.