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Mercedes Benz ML350 Ignition Switch Replacement: Everything You Need to Know!

Mercedes Benz ML350 Ignition Switch Replacement

Purchasing a Mercedes Benz can be satisfying if you dream of owning a luxury car. Who wouldn’t be? Mercedes Benz is one of the best automakers in the world. But with owning one, you have to prepare for its maintenance and repair costs that could be a bit more expensive than usual. Don’t get me wrong, Mercedes Benz is a reliable car but it can also develop problems that will need repairs or part replacements. Just like the ML30, one of its common problems is a faulty ignition switch that warrants an ML30 ignition switch replacement. You will know that you need a replacement or repairs when you notice that your car does not start when you turn the ignition, your car is not identifying its electric key anymore, instrument panel lights don’t turn on, and other issues that we will discuss later on. 

Auto Repairs Are EXPENSIVE


Mercedes Benz ML350 Ignition Switch Replacement: How do I know if I have a bad ignition switch?


The Mercedes Benz M-Class Series which is the ML350 is a part of is a decent two-row luxury midsize SUV that offers a high-class interior and a comfortable ride. It is equipped with user-friendly technologies and a powerful 3.5 L V6 cylinder engine. Although it has been discontinued after its 2015 model year, the ML350 is still being used up to this day and you might find many used ML350s being sold in the automotive market. 


No matter how reliable or sturdy the ML350 is, it can still develop problems with its components. One of its components that is prone to failure is the ignition switch. The ignition switch is more than just a slot where you stick your key in. In fact, the key slot is technically called an ignition lock cylinder and not an ignition switch. The ignition switch consists of complex electrical components that read codes in the key before it activates the vehicle's electrical system. Once the electrical system has been activated, you can then use the vehicle, start it and be shifted out of park. 


An ML350 ignition switch replacement might be needed if your ML350 really has a failing ignition switch. How can you know if you have a bad ignition switch? Here are the common symptoms of a bad ignition switch.


  • Key does not turn.  


A key that does not turn is a sign that you have a faulty electronic ignition switch. It is because when the system fails, the car won’t be able to recognize your key because the turn and start function has been deactivated by the system. 

  • Car won’t start.


One common sign of a failing ignition switch is if your car is not starting when you turn the key. Wear and tear can happen to any car components including the ignition switch. Keep in mind that there are also other possible reasons why your car is not starting. It is better that you have your ML350 checked to get the right diagnosis.

  • Car stalling. 


When your car suddenly stalls while you are driving or while the engine is operating, it can be an indication that you have a failing ignition switch. A faulty ignition switch can fail while the engine is running and it can cut off the power to the ignition and the fuel system and it can result in car stalling. Worn contacts inside the ignition switch can cause this that leads to a brief loss of voltage caused by heat or vibration.  


  • Instrument panel lights not turning on.


Another symptom of a failing switch that could warrant an ML350 ignition switch replacement is that when you turn your ignition, your instrument panel doesn’t light up as it's supposed to. Normally, the instrument panel will light up first when you turn the ignition. If you inserted the key, turned it, and the accessories did not light, it can be because of a faulty ignition switch or a faulty ignition lock cylinder. 


When you experience this issue, it is recommended that you have it checked and diagnosed since the same issue can also be caused by a faulty fuse and wiring issues. 

  • Starter rotor has no noise. 


To rule out that the ignition problem is not caused by the starter rotor, you can try to listen for the sound coming from the starter rotor. You should hear the starter motor operating, if you can’t hear anything then the problem is caused by a failing ignition switch. If it is the starter rotor that is failing, you will usually hear a click sound. 

  • Difficulty in removing the keys.


You might encounter problems trying to remove your car keys. It can be caused by a binding in the steering column lock. You can try to jiggle or shake slightly the steering wheel back and forth until you feel something click into lock position. Doing this can help you get the key from the ignition. If the key can’t still be removed, the problem might be caused by a damaged column locking mechanism. If the key has been removed and the engine is still running, it is an indication that you have a faulty ignition switch.


The OBD trouble codes that you may find that are related to a failing ignition switch are P2536 or ignition switch accessory position circuit, P2538 or ignition switch accessory position circuit high, and P2537 or ignition switch accessory circuit low. 


Mercedes Benz ML30 Ignition Switch Replacement: What causes ignition switch failure?


Mercedes ignition switches usually last a long time but there are some contributing factors that decrease its lifespan that brings about the need of an ML350 ignition switch replacement. One of the common causes of an ignition switch failure are worn contacts. Worn contacts tend to lose their ability to make perfect mechanical contact that could trigger a failure. These contacts can also begin to oxidize because of heavy amperage flow that develops electrical resistance that lessens amperage flow through the ignition switch.


Weather can also become a contributing factor of a faulty ignition switch. There are instances  where the internal sliding contacts are heavily greased during assembly causing it to harden in cold weather that hinders its mechanical contact.


Heavy accessory loads can also cause ignition switch failure. This happens when the internal sliding contacts become heavily oxidized or have yielded to heat distortion and loss of mechanical integrity. 


Another thing that can cause an ignition switch failure are heavy keychains. Do not carry a lot of keys or a heavy kind of keychain if you want your ignition switch to last longer and avoid having an ML350 ignition switch replacement.


Mercedes Benz ML350 Ignition Switch Replacement: Is an ignition switch expensive to replace?


The ignition switch plays an important role in the ignition system. It is part of the starting and the charging of the vehicle. The ignition switch also works as a power switch for a number of electrical components of the vehicle.


If your ML350 ignition switch is failing, you might need an ML350 ignition replacement. The estimated cost for a ML350 ignition switch replacement is between $528 and $549. The parts are priced at $446 and the labor cost can go from $82 to $103. The price can vary depending on its condition of the car and other factors. 


It is important that if you are due for an ML350 ignition switch replacement and you are experiencing symptoms of a faulty one, you should do it as soon as possible. It is dangerous or it is impossible for you to drive a vehicle with a failing ignition switch. Depending on the severity and the point of the failure, you can get stranded, be stalled in the traffic, or even fail to turn your engine off even after removing the key. 


Before concluding that you really need an ML350 ignition switch replacement, you need to be sure first that a faulty ignition switch is really what’s causing the problems. A thorough diagnosis should be done since some of the symptoms can also be caused by a worn key. Remember that the ignition switch can be referred to as an assembly that consists of an ignition lock cylinder and the ignition switch. These parts can be replaced individually or be replaced as a whole unit depending on the type of failure. 

Mercedes Benz ML350 Ignition Switch Replacement: How do you remove the ignition switch on a Mercedes?


Like any other parts of the car, theML350 ignition switch is susceptible to wear and tear too. If it fails, you won’t be able to start your car and you might need an ML350 ignition switch replacement. It is advised that you let the experts handle the replacement but if you would like to know how to remove an ignition switch and do it yourself, follow these steps.


  • First thing you should do is to adjust the telescoping steering wheel of your Mercedes Benz to the maximum extended position or the maximum out position. 
  • Next is to shift the front driver's seat to the rearmost position.
  • Disconnect the negative battery cable. Loosen the retaining nut on the negative battery cable clamp and slide the clamp off the battery terminal. 
  • Loosen and remove the screws of the instrument panel’s underside, the part that holds the instrument cluster cowl in place. Remove the cowl.
  • Remove the other four screws that hold the instrument panel in place and take off the instrument cluster from the dash. Remember to take off the electrical connectors from the back of the instrument cluster first before trying to remove the cluster completely.
  • The next thing you can do is to turn your ignition key to the “I” position. Take off the electrical plug found in the back of the ignition switch. 
  • Loosen the Allen bolt on top of the ignition cylinder that mates with the steering column. Do not remove the bolt. You can use an Allen wrench to loosen it.
  • Loosen and remove the two 13 mm bolts fastened on top of the steering column. Doing so enables the steering column to drop down about 3 inches. This allows you to access the release button for the ignition switch.
  • Locate the release button on the steering column where the ignition cylinder meets the column and press it. 
  • Insert the key and turn to the “I” position. Remove the ignition cylinder and switch assembly. You can remove it by pulling it out of the steering column.
  • Take off the ignition wiring from the back of the ignition switch and cylinder assembly. You can remove it by pressing down the release tab found on the electrical connector and by pulling it off the switch.


In doing this process, you might want to document it, take pictures or a video to know which part goes to where. It will be easier for you to reassemble the parts after replacing your ignition switch if you follow the tips on how to dismantle car components properly.


Mercedes Benz ML350 Ignition Switch Replacement: How do I reprogram my Mercedes key?


Depending on the Mercedes Benz vehicle you have, you might need to recut or reprogram your ignition key if you replace your ignition switch. To reprogram your Mercedes Benz key, follow these simple steps.


  • Insert your key in the ignition.
  • Turn the key to the “On” position.
  • Get your Mercedes Benz keyless remote. Press and release its lock button.
  • Press and hold its unlock button. 
  • While the unlock button is still held, press your remote’s lock button consecutively five times at one or two seconds intervals.
  • After pressing the lock button the fifth time, release both the lock and unlock button and wait five seconds.
  • Press the lock or unlock button once to complete the programming process. 



ML350 Ignition Switch Replacement: Final Word


It is important that you follow and go through an ML350 ignition switch replacement if it has been advised. It is one of the most often used switches and is susceptible to wear and tear and other flaws. It is best that you have it replaced if it is needed since the ignition switch is the one that draws power from the battery and sends it to your starter and your electrical components. 


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