Contents: Crankshaft speed sensor ↡ Electronic control unit (ECU) ↡ Coolant temperature sensor ↡ Throttle Position Sensor ↡ Incoming air temperature sensor ↡ TDC position sensor ↡
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. The sensor is located on the mating surface between the cylinder block and the clutch housing, above the starter hole. Loosen 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. 7.5, a, b).
Fig. 7.5, a. Location of the electronic ignition control unit (shown by arrow) — models with TSZ ignition system
Fig. 7.5, b. Location of the electronic ignition control unit (shown by arrow) — models with EZL ignition system
6. Disconnect the negative battery terminal.
7. Disconnect the multi-pin connectors from the control unit, marking each one to avoid confusion during installation.
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 has a heat-conducting paste applied to it to improve cooling - try not to stain the surrounding parts with the paste. Do not remove the protective solder.
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 part of Chapter 4.
(Article based on data from the website: «MERCEDESMAN»)
Throttle Position Sensor
12. The ignition system shares a common throttle position sensor with the fuel system - refer to the information provided in the relevant section Chapters 4.
Incoming air temperature sensor
Removal
13. The incoming air temperature sensor is located on the side of the air cleaner housing.
14. Make sure the ignition is off. Then disconnect the sensor wires at the connector.
15. The sensor has a bayonet type connection - squeeze the tabs of the clamps, turn a quarter turn and remove it from the air cleaner. Remove the seal.
Installation
16. Installation is carried out in reverse order.
TDC position sensor
17. 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 relative to the end of 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.