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ML 350 Won’t Start – Top Reasons Why

ML 350 Won’t Start – Top Reasons Why

Jumped into your ML350 only to discover that it won’t start? Your first reaction might be to start panicking especially if you are running late for work or you have somewhere important to be. Unfortunately, mechanical problems always seem to occur at the most inconvenient times and it can be incredibly frustrating. When your ML350 won’t start it’s important to remain calm so that you can troubleshoot the vehicle and determine whether it’s a minor issue that can quickly be fixed.

Auto Repairs Are EXPENSIVE


ML 350 Description

The Mercedes 350 is a midsize luxury SUV manufactured by the German automaker Mercedes Benz. The 350 replaced the ML 320. The ML350 is the perfect crossover for consumers that desire a vehicle that can accommodate their growing families without having to compromise on luxury. 


The ML 350 which is part of the M-Class series is equipped with a 3.5 L six-cylinder engine. With 302 horsepower this crossover packs a powerful punch which is expected for this classic luxury brand. 

The ML 350 was discontinued after the 2015 model. The average cost of a used ML 350 is approximately $25,000. 


ML350 Won’t Start – What’s The First Thing You Should Do?

Usually, when your car won’t start it’s because of a dead battery, a bad alternator, or an issue with the starter. However, there are a plethora of mechanical issues that can cause your ML 350 not to start. 


The sound your Mercedes makes or doesn’t make when you attempt to get the engine to turn over can give you some insight into what might be going on under the hood. If the car clicks when you turn the key in the ignition but still the vehicle still won’t start the battery may be dead or the terminals might be corroded.


If you don’t hear a clicking sound when you attempt to start the car the issue could be the alternator. You might feel helpless but here are some things you can do to try to get your car started. 


Try Cycling The Key in the Ignition

Try putting the key in the ignition. Does the car turn on? Does the radio work? How about the exterior lights? Turn on your headlights and try to start the engine at the same time. If the headlights flicker out then this is a sign that the battery has very little juice left or is completely dead. 


The key cycling trick can help you heat the battery, the terminals, and the starter. Turn the key to the start position about ten to fifteen times. Next, stop and wait for about five minutes and then try to start the car. If the engine doesn’t turn over but the headlights remain bright when you turn the key this is a good sign. 


Lightly Tap On The Battery Terminals

If your headlights are shining the battery might not be providing any power to your car because the battery terminals are corroded or they aren’t properly adhered to the battery.


 Corroded terminals can considerably weaken the connection which makes starting the car difficult. Corrosion eats away at the metal. Eventually, you will have to replace the terminals on your battery if they are heavily corroded and can't be cleaned. 


Oftentimes when the battery terminals are corroded the battery itself is corroded as well. Corrosion produces acid that will weaken the battery and render it useless. 


Try cleaning off the corroded battery terminals. You can remove all of the corrosion from the battery terminals by using a mixture of baking soda and water to make a paste. Next, adjust the terminals around the battery to make a better connection. 


Tap On the Starter 

If you can easily access the starter on your Ml350 try shifting it around or smacking it. Oftentimes the electrical contacts get stuck and this can prevent the starter from functioning normally. Giving the starter a hard tap with the tire iron. 


Shifting To Neutral 

In some instances, shifting the gear to neutral can help start your car. Put your feet on the brake and move the gear shift to the neutral position. Shift the gear back into Park and then Neutral again if it doesn’t work. 


Hit The Fuel Tank

If your ML 350 won’t start try hitting the bottom of the fuel tank with your foot. This can help get the fuel pump motor running. 


Is It the Battery or Alternator?

When your ML 350 won’t start you might automatically assume it's the battery or the alternator. In colder weather, it’s quite common for the battery to have a dead battery. Checking the battery gauge on your ML350 is a great way to determine if the battery is being charged even with the car turned off. 


Check the automatic windows, the windshield wipers, and the brake lights. Are the wipers moving slowly across the windshield? You can use a portable jump starter or have a friend give you a jumpstart to see if that jolts your battery back to life. When you give your car a jump make sure you give the battery sufficient time to charge. 


If your battery loses power after turning your car off and restarting it. This could mean that the alternator isn’t fully charging the battery.


How Can I Tell If the Alternator Is Bad?

When the alternator fails in the ML350 the dashboard battery warning light will be triggered. All of the electrical components in the vehicle and the engine will stall and jump-starting the battery won’t work. 


In most ML 350s the alternator can last for about 100,000 miles. Custom power accessories and harsh driving conditions can cause the alternator to wear prematurely. 


Can I Drive With A Bad Battery or Alternator? 

Sometimes the engine might start with a bad battery or alternator. After a while jump-starting the battery won’t get the car running. When you are driving with a bad battery or alternator the car will eventually lose power. Driving with a bad battery and a failing alternator is dangerous. 


Replacing the battery on your Mercedes will cost about $299-$312 while installing a new alternator is $573-$741. 


ML 350 Won’t Start – Common Starter Problems 

Problems with your car’s starter can also cause it to lose power and not start. The ML 350 electric starter is powerful and capable of turning the engine over at 200 RPM. The starter is connected to the circuit that is also connected to the battery, ignition switch, relays, and switches. 


While the Mercedes starter is durable in the following situations the starter will fail:


Starter Begins Turning Too Slow

Electrical and mechanical failures can result in the starter sucking up too much current. As a result, the current drawn will exceed what the battery can hold. The engine won’t be able to turn over as fast. 


Unusual Noises When Starting 

Do you hear grinding or any other unusual noise when revving up the engine? This noise could signal internal starter failure. The noise may be caused by a faulty pinion gear. 


Intermittent Starter Operation

When the starter develops bad spots in the armature starter operation becomes unreliable. This causes the starter to work intermittently.


Is It Safe To Drive With A Bad Starter?

Once the car is started the starter is no longer in use. But driving a car with a bad starter can be dangerous. After all, you never know when the starter will start malfunctioning or completely give out. You could end up stranded. 


Installing a new starter in your ML 350 will cost you about $657-$721.


ML 350 Won’t Start – Check The Fuses and Relay

When your Mercedes won’t start and it's not the battery, starter, or alternator you should check the fuses and the relay. Check the fuses for the starter ignition, fuel pump, ignition, and EIS. If you are not sure which fuse is which you can always check to see which ones are burned out.


When you are installing new fuses make sure you replace the old ones with fuses that are within the same ampere rating. If you don’t the fuse will quickly burn out again. 


You can also test the ignition, fuel pump, and starter ignition fuse with a digital multimeter. Using a multimeter is a great way to check the fuses without having to remove them.


 Check The Brake Light Switch 

The brake light switch in Mercedes Benz is often the culprit behind starting problems. The Drive Authorization is an anti-theft feature that can prevent the ML 350 from starting if the brake light switch is malfunctioning. Sometimes the Drive Authorization module fails to recognize the keys. For the car to start a new module will need to be installed. 


Most of the time you will notice when the anti-theft system is preventing the car from starting because you won’t be able to shift the gear out of the park. 


ML 350 Won’t Start -Fuel Problems 

When your ML 350 won’t start you should rule out any fuel-related problems. Fuel problems can be difficult to identify. A failed fuel pump or fuel relay can cause your ML 350 to not start. One way you can determine whether your car has a fuel related problem

Is by checking the fuel pressure with a fuel pressure gauge. 


You can purchase a fuel gauge from your local auto parts store. You’ll have to pop the hood and connect the gauge to the Schrader valve test port. Next, start the car. The fuel pressure gauge should read 60 psi. When you turn off the engine the pressure should remain steady. A pressure test should always be conducted on a cold engine.


In the ML 350, you should be able to hear the fuel pump operating by listening carefully to the fuel or gas tank. However, for this to work, you will need to turn the key in the ignition. If the fuel pump is functioning properly you should hear it running for several seconds. Also, check the fuel filter to make sure it’s not clogged up or worn. Sometimes replacing the fuel filter will resolve your vehicle's starting problems.


Replacing the fuel.pump on a ML 350 is between $920 and $1,052.


ML 350 Won't Start – Faulty Spark Plugs


The ML 350  is equipped with two sparks. plugs for each cylinder. If your car has six cylinders you then you have 12 spark plugs. The spark plugs are an essential component of the ignition process. It ignites the fuel and air in the engine giving it the power for you to take off. The spark plugs produce a spark during the engine’s combustion process. When the spark plugs become worn or soiled with fluids like motor oil you’ll experience difficulties starting your vehicle. 


Even if one of the spark plugs fails they will all need to be replaced. While driving with faulty spark plugs is possible it will eventually cause damage to the engine. The average cost for replacing the spark plugs is between $426-$569. 


Is The ML 350 A Reliable Car?

When you are dealing with starting problems your probably wondering whether the ML 350 is a reliable vehicle. This M-Class model has a reliability rating of 3.5 out of 5. According to Repair Pal, a trusted source in the automotive industry the ML 350 is one of the top-rated luxury car models. However, maintaining and repairing this high-end vehicle can be costly. 


Fortunately, most of the starting problems the Mercedes-Benz 350 has are typically a result of a bad battery, a failing alternator, or a faulty starter. Therefore, nine times out of ten if your ML 350 won't start it's due to a minor problem. While the costs associated with replacing a battery, alternator, or starter is higher in an ML 350 than it would be in an average car it won't break your pockets. 


If fuel pump failure or engine-related problems are the reason why your ML 350 won't start you’ll have to decide whether repairing the issue is worth the cost. For some people spending $3,000 to repair a car just isn't in the budget. Cash Car Buyers purchases vehicles in all kinds of conditions.