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Mercedes Benz ML350 Ignition Problems: Everything You Need to Know!

Mercedes Benz ML350 Ignition Problems: Everything You Need to Know!

The ML350 was part of the Mercedes Benz M-Class that debuted in 1998. It was sold as a midsize crossover SUV through 2015 until it was replaced and rebranded as the GLE-Class. The ML350 trim of the Mercedes Benz M-Class has been the most popular one of the SUV's range. Although ML350 has been discontinued after model year 2015, many ML350 units are still being sold and are still running today. As reliable as the Mercedes Benz vehicles are, they are still susceptible to problems and there have been several ML350 ignition problems that are reported. Some of the reported ML350 ignition problems include stalling engine, car not starting, keys not turning, no sound when turning the ignition, and other ignition switch issues. 

Auto Repairs Are EXPENSIVE


Mercedes Benz ML350 Ignition Problems:  What would cause a Mercedes not to start?     


The ignition system of the car is the one that ignites the air-fuel mixture in a gasoline engine.  The ignition system has several components that work together to make sure that the job is done correctly. Its components include the battery, distributor cap and rotor, ignition coil that includes coil packs or Coil- On-Plug (COP), spark plug wires, spark plugs, ignition module, powertrain control module or PCM, crankshaft and camshaft sensors, and knock sensor. 


Although the technological advancements of the modern cars have greatly lessened the need for ignition system services, there are still some problems the modern vehicles encounter with their ignition systems and the Mercedes Benz ML350 is not exempted.


Here some of the most common Mercedes Benz ML350 ignition problems.

  • Car not starting.


There are many ML350 owners that reported that they experienced having problems with their cars not starting. There are a number of reasons why the Mercedes Benz ML350 won’t start but the most common reasons are a dead battery, faulty starter, or a faulty alternator.


Cars not starting can be encountered in several ways. 

  • Engine dies after starting it. 


It can be frustrating when your car won’t start after many attempts and when it does, it dies. It is a hassle especially if you have to be somewhere and you are already running late. This can happen when you have issues with your ignition or injection system, your low idle speed needs adjustment, the carburetor needs adjustments, vacuum leaks, or you have faulty sensors. 

  • You hear a clicking noise but the noise but the engine won’t start.


You might have experienced turning the key to the start position, you hear a clicking noise but the engine doesn’t start. It might also come as a repeated clicking noise coming from the engine compartment.  This problem can occur when you have a low battery or your connection between the battery and starter is poor. 


To correct the issue, you need to inspect your battery and your terminal cable connectors thoroughly. Check for corrosion and other contaminants. If you find corroded connectors and battery posts, make sure that you clean them or replace them if necessary. 


You can also check the starter since the solenoid attached on its top can fail and the components inside. If these components are faulty, you might need to repair or replace starter solenoids, starter contacts, starter assembly, or the  starter circuit.

  • Engine cranks over but it won’t start. 


Before you worry about this Mercedes Benz ignition problem, make sure that you have checked your fuel. If your vehicle is out of fuel, it won’t start. If your car has fuel but won’t start, it could be because of the fuel not getting into the engine. Check your fuel injectors and clean them. This problem could also indicate that you have problems with your fuel pump, fuel injectors, fuel filters, and fuel lines. 


If the problem is not fuel-related, it could be because of the spark plug. It could happen when the electrical spark is not getting through the spark plug. Check the spark since without one, the engine will not start. The spark ignites the fuel mix in the combustion chamber that will start the engine. Spark issues are not caused by spark plugs alone, it could also be caused by spark plug wires, the distributor, and the plug gap. 

  • When you turn the ignition, there is no start, no crank, and no sound.


When you insert your key in the ignition but nothing happens – no start, no crank, no sound – it would mean that the starter rotor does not turn over the engine. This problem is usually caused by a low or dead battery or the connection between the battery and the starter is faulty. 

  • Ignition lock and tumbler failure.


One of the Mercedes Benz ignition problems is an ignition lock and tumbler failure. A car has an ignition lock cylinder that consists of the tumbler and key assembly which is needed to start a car. An ignition lock cylinder is the keyhole that drivers use to power up their cars. 


The ignition lock and tumbler failure can cause these problems.

  • Difficulty in starting the engine.


Struggling to start your engine is one of the symptoms of an ignition and tumbler failure. The problem can occur when the ignition lock becomes worn. Whenever you start your vehicle, you use the ignition lock and tumbler. It is already given that the vehicle’s components experience wear and tear over time and the ignition lock is not an exemption. 


There may be times when you experience that you need to do a certain key position or movement to make the key work. This problem is also caused by a worn ignition lock and it could get worse over time. It is best that you have it checked and repaired immediately.


  • It is hard to insert or remove the key. 


The ignition lock cylinder wears down over time and it can result in worn cylinders jamming up the key when you insert it, turn, or remove it. Difficulty in inserting the key or removing it from the tumbler is one of the Mercedes Benz ML350 ignition problems. 


If you have experienced this problem in your vehicle, have it repaired as soon as possible since the jamming and the binding of keys can eventually result in the inability to start your vehicle. It is because the ignition lock cylinder is connected to the electronic ignition switch. When it can’t turn to the power position, it won’t be able to engage with the electronic ignition switch which causes a no-start condition. A vehicle with a no-start condition can also be caused by some other faulty components. For this reason, you need to have your ML350 checked immediately to get the correct diagnosis. 


There are many possible reasons why you experience Mercedes Benz ML350 ignition problems. Here are some of the common causes:


  • Battery. 


Most of the Mercedes Benz ML350 ignition problems are caused by either low or dead batteries. If you have an old battery, you might need to replace it with a new one to fix the problem. If your battery is new but you experience ignition issues, you can do a battery check to make sure that it is not the one that causes the problems. 

  • Brake light switch. 


There are instances where the Mercedes Benz Drive Authorization System is not allowing you to start your car. The reason for this problem might be a faulty brake light switch. Faulty brake light switches can result in lights not turning on and driving without lights can be dangerous. 

  • Fuse and relays.


If you already checked your battery and it is not the cause of the Mercedes Benz ML350 ignition problems, then you can proceed in checking your starter circuit, ignition, Electronic Ignition Switch or EIs, or your fuel pump fuses. The fuse is also susceptible to faults and issues since it is the one that gets all the brunt and can be burned out. Keep in mind that if you change a fuse, make sure that you replace it with the same ampere as the original one. 


  • Gear selector module. 


You will know if the gear selector module is defective when you notice that the gear indicator on the instrument cluster does not change from letters P to R to N when you move the shifter from Park to Reverse and to Neutral. 

  • Fuel problems.


Fuel issues can also cause Mercedes Benz ML350 ignition problems. To make sure that you do not have fuel issues, check it by using a fuel pressure gauge with a Schrader valve adapter. 


To check it, you need to turn off your engine, connect the gauge to the Schrader valve test port, and start the engine once it is connected. You will know if the pressure is steady if you get around 60 psi even when you stop the engine. 


You also need to check your fuel pump and fuel pump relays. Make sure that you hear the fuel pump run every time the key is turned  in your ignition to position 2. You can ask someone to turn the ignition for you so you can listen closely. If you can’t hear the fuel pump, then you have a faulty one. It is also important to replace your old fuel filters since it tends to clog up. 


  • Faulty crankshaft position sensor. 


A faulty crankshaft position sensor can also be the reason why you are having problems starting your car. It can also cause a number of issues such as a car starting intermittently, car misfiring, hesitation when the car starts, vibrating engine, engine stalling, and it can also set off the check engine light.


It is recommended that if you experience any of the symptoms of a faulty crankshaft position sensor, you need to have it fixed immediately or have it replaced. 


Mercedes Benz ML350 Ignition Problems: What is the EIS system for Mercedes-Benz?


There are some Mercedes Benz ML350 ignition problems that are caused by a faulty EIS system or the Electronic Ignition Switch. But what is an EIS system?


The Electronic Ignition Switch and the ESL or Electronic Steering Lock system is designed to ensure that your vehicle will not be stolen. This is made possible with the help of your key that has a sequential code that is unique to your vehicle. When the key is inserted in the ignition, your vehicle will run a number of tests to make sure that it is the correct key. The EIS, ESL, and the ECU or the Engine Control Unit will need to agree together that it is the correct key to activate the “Turn and Start” function. The “Turn and Start” function will be deactivated if the key and the EIS don’t match up.


If you have a faulty EIS ESL system, you will experience several ML350 ignition problems such as your car is not starting, can’t turn your key in the electronic ignition switch, you can turn your key but it will not start, or your car will not start when it's cold


A faulty EIS ESL system can cause the “Turn and Start” function to be deactivated. It happens not because you inserted the wrong key but because of a communication breakdown in one of the control units. A power surge, doing a jump when the key is inserted, low battery, or an Electronic Steering Lock Fails or locks in place can contribute to an EIS ESl failure. To correct the problem, you may have to replace your ESL which is a pretty expensive fix.


Mercedes Benz ML350 Ignition Problems: Is the Mercedes Benz ML350 reliable?


The Mercedes Benz ML350 is a good and reliable car. It has a reliability rating of 3.0 out of 5.0 which is average for its class. As for its maintenance, its total annual cost for maintenance and repairs is around $1,020 which is higher than the average $810 annual maintenance cost for  other luxury midsize SUVs. Part of the cost might be from the repairs made for the ML350 ignitions problems.  


We now have an idea that the Mercedes Benz ML350 ignition problems are often caused by the battery, fuse, wirings, and other important components. It is best that you always take time to inspect these components and do preventive measures to make sure that you won’t get to experience these ML350 ignition problems. Proper maintenance and services can also help prolong your ignition system.