Generator A6361540102 0124525054 F00M144157 2721540002 0399604015 is suitable for Mercedes Benz C230 C280 C300 C350 2005-2011

Pre-installation Preparation

• After parking the vehicle steadily, pull the handbrake tightly, turn off the engine, and disconnect the negative battery cable to avoid short circuits that may damage electrical components during operation.

• Prepare suitable tools, such as socket wrenches, a dedicated belt tensioner tool, a torque wrench, rags, and an OBD diagnostic tool for subsequent parameter matching.

• Confirm that the new generator is compatible with the vehicle model. Prioritize Mercedes-Benz original factory or officially authorized accessories, and verify that key dimensions such as the number of pulley grooves are consistent with the old unit. Meanwhile, take photos to record the belt routing to prevent incorrect routing during reinstallation.

Removal of the Old Generator

• Open the engine compartment and perform corresponding preprocessing according to the vehicle model. For example, the air filter housing needs to be removed for the 111-series engine, and the front passenger side air intake pipe must be detached for the 112-series engine.

• Use the belt tensioner tool to loosen the tensioner, release the belt tension, and then remove the drive belt from the generator pulley. Be careful not to get grease on the belt.

• Press the plastic buckle of the generator wire connector, pull it out carefully, then use a wrench to remove the output terminal nut and disconnect the B+ power cable. You can mark the connector position in advance to avoid incorrect connection.

• Use a socket wrench to loosen and remove the generator's fixing bolts. For some models, the bolt spacers also need to be taken out, and then the old generator is removed from the engine compartment. If the bolts are rusted, spray rust remover and let it stand for a while before operation.

Installation of the New Generator

• Thoroughly clean the generator's mounting position of dust and oil with a rag to prevent impurities from causing unstable installation or abnormal vibration.

• Place the new generator stably in the mounting position and align it with the bolt holes. If there are spacers, install them back to the corresponding positions first. Initially tighten the fixing bolts by hand without fully securing them.

• According to the previously marked positions, accurately connect the wire connector and the B+ power cable, and tighten the terminal nut. The B+ terminal nut should be tightened according to the vehicle model specifications — the torque for some diesel models needs to be controlled at 14N・m, and the D+ terminal bolt is generally tightened to 5N・m.

• Adjust the generator's position to ensure its pulley is aligned with the engine-side pulley, then use a torque wrench to tighten the fixing bolts according to the original factory standard. The torque for this bolt is 42N・m for most Mercedes-Benz models, and 20N・m for some diesel models.

• Operate the belt tensioner to put the drive belt back on the generator pulley according to the recorded routing, and adjust the tension. The ideal deflection when pressing the midpoint of the belt with the thumb is 5-6mm.

Matching and Commissioning

• Reconnect the negative battery cable. For some models, it is necessary to re-enter the radio code and adjust the clock.

• Connect the OBD diagnostic tool to the vehicle, access the control system to find the generator settings option. For example, the Mercedes-Benz M274 engine requires activating the voltage regulator with the diagnostic tool, entering the new generator parameters, and completing initialization.

• Start the engine and observe whether the charging indicator light on the instrument panel turns off normally. When the engine is idling, use a multimeter to measure the output voltage — the normal range should be 13.5-14.5V.

• Let the engine idle for 3-5 minutes to check for abnormal noise, then conduct a short-distance driving test. Confirm that no fault lights are on and the power generation status is stable.

1. Safety Operation Red Lines

• Keep the negative battery cable disconnected throughout the process and do not reconnect it until installation and wiring are fully completed, to avoid short circuits that may burn the ECU or generator.

• Wear insulated gloves and goggles during operation. Oil pipes and coolant pipes in the engine compartment are fragile; avoid collisions or damage that could cause leaks.

• Tools must be insulated and compatible with bolt specifications. Do not use brute force on rusted bolts — spray rust remover and let it stand before operation to prevent bolt stripping or housing damage.

2. Vehicle Model Adaptation and Accessory Requirements

• The new generator must be accurately matched to the vehicle’s engine model (e.g., M274, 111, 112, etc.). Verify that the number of pulley grooves, mounting holes, and terminal types are consistent with the old unit.

• Prioritize Mercedes-Benz original factory or officially authorized accessories; reject low-quality aftermarket parts to avoid power generation abnormalities or electrical system damage due to incompatibility.

• Take photos in advance to record the belt routing. Belt paths vary significantly across different Mercedes-Benz models; incorrect routing during reinstallation can cause belt wear or breakage.

3. Installation Accuracy Control

• Thoroughly clean the mounting position, ensuring it is free of oil and impurities. Residues may lead to generator vibration, abnormal noise, or loose fixing bolts.

• The generator pulley must be strictly aligned with the engine-side pulley, with a deviation not exceeding 1mm. Excessive deviation will accelerate belt wear or cause it to fall off.

• Tighten bolts according to model-specific torque standards: most models require 42N・m for fixing bolts (20N・m for most diesel models), approximately 14N・m for B+ terminal nuts on diesel models, and 5N・m for D+ terminal bolts. Use a torque wrench for operation.

• Precisely adjust belt tension: the ideal deflection when pressing the midpoint with the thumb is 5-6mm. Overly loose belts may slip, while overly tight ones will damage generator bearings and engine accessories.

4. Electrical Connection and Matching Specifications

• Follow marks strictly when wiring; do not reverse B+ and D+ terminals. Ensure connectors are fully locked and sealing rings are intact to prevent water ingress and short circuits.

• After installation, use an OBD diagnostic tool to complete parameter matching. For example, the M274 engine requires activating and initializing the voltage regulator. Failure to match will result in abnormal charging.

• For some models, re-enter the radio code after reconnecting the battery to avoid electronic device locking.

5. Commissioning and Taboos

• After starting the engine, first check if the charging indicator light turns off. Let the engine idle for 3-5 minutes, measure the voltage (13.5-14.5V), and only drive after confirming no abnormalities.

• Do not start the engine without the belt, with incorrect belt routing, or abnormal tension. This will cause the generator to run idly and damage bearings.

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References：

Qiche Dashi (Car Master)

Mercedes-Benz-Specific Maintenance Data Websites

General Automotive Maintenance Knowledge Platforms