Why Won’t My Mercedes Benz Start After Replacing A Car Battery?

This has to be the most frustrating thing you’ve faced as a Mercedes Benz owner. You’ve been meticulously maintaining your vehicle for as long as you’ve had it. You’ve never skipped an oil change, always checked your car when the check engine light comes on. Your car is in tip top shape. If it were an athlete, it would probably be the best quarterback in the league.

Recently though, after years of faithful and timely service, wear and tear has slowly taken a toll on your battery. It has come to a point where you’ve had no other option other than to replace it. Old faithful is away, time to make your car purr with renewed vigor. Pop into your car and click. The car won’t start.

Mercedes won’t start after replacing a car battery, why? There could be a variety of reasons why your vehicle does not start. Some of the problems could include the starter not receiving electrical power from the battery, the spark plugs as well are not receiving any power, or the vehicle’s Drive authorization system is preventing you from starting the car.

For a proper diagnosis of why your car isn’t starting, let’s take a deep dive into the various reasons your Mercedes is not starting.

1. Check the Battery

Yes, it may be new to your Mercedes-Benz, but it’s not exactly a spring chicken. It may have been lying on the shelf for years before you picked it to put it in your vehicle. Lead acid batteries are not meant to discharge completely lest they stop working. When that are stored, they should be stored with a full charge.

If the battery has been on the shelf for some months, it could have completely bottomed out as a result of self-discharging. Lead-acid batteries self-discharge and the rate increases with increases in temperature. For temperatures below 50 degrees Fahrenheit, the discharge rate will be about 6 percent for every month it is on the shelf. For temperatures greater than 90 degrees Fahrenheit, as much as 20 percent will be lost to self-discharge every month.

Before you begin blaming your car for not starting, check the battery whether it contains enough charge to crank over your car’s engine. If it is flat, you will need to charge it using a trickle charger otherwise you risk increasing the rate of degradation.

You might also need to check whether the battery was stored dry, or if it had any fluids in it. If there are fluids, you may need to check whether they are at the correct levels. If not, simply top them up and then use a trickle charger to recharge it.

Your old battery may also have left you several layers of parting gifts on your battery cables. Some corrosion may have caked on the terminal connectors causing problems with flow of power from the battery. You will need to take a brush and scrub the terminal connectors until they are free and clear of any gunk that may have accumulated. (Read more details on how to clean car battery terminals).

2. Check Switches

The onboard Drive Authorization System will not allow the engine to start if you have a problem with a switch that connects to the braking system. You may try to put your foot down on the brake pedal and the brake will light up. However, this switch is composed of two microswitches and the malfunction of one will mean that the brake lights will still come on.

Unfortunately, this is a common issue with many owners who end up having their Mercedes towed to the shop, only to be told that a switch costing less than $5 is the cause of this problem.

In some other cases, trying to shift gears may be a problem. It can actually get stuck in the park position. This broken switch will also cause the Drive Authorization System to cut out any power to the engine.

In other cases, you may be able to move the gear selector but the vehicle will still be stuck in the gear it was in when the switch broke. A simple way to find this out is to utilize the instrument cluster on the dashboard, specifically the gear indicator. Try and move the gear selector to different gear positions. You may notice that the light on the gear selection indication is still in the same place it was in even though you’re moving the gear lever.

This switch causes car owners headaches, and it itself goes for less than $20.

3. Starter Motor and Other Electronics

Each vehicle has its own characteristics. It is most probably why car owners end up naming their vehicles because these characteristics are so individualized to that particular vehicle, it is similar to that of a human being. One of these quirky characteristics is how the starter will respond to the new battery.

Your starter may have worked very well with your old battery but the moment the new battery is installed, it stops working. This could be as simple as the fuse that allows power to flow to the starter has blown out. In some cases, it may just need a bit of TLC with percussive maintenance. That’s a fancy way of saying pick up a rubber mallet and give the starter a few love taps. Surprisingly, this works.

If it does work but then later refuses to, you may also consider replacing the starter as it has reached the end of its useful life.

A common problem that most people may have attributed to a bad battery or starter cold be the beginning of failure of the spark plugs. Even though they have no moving parts, the amount of electricity that flows through them is enough to cause wear and tear as if it did have moving parts.

If your engine was misfiring before, or was not providing you enough power as it did before, your spark plugs could be a big equation of the problems your engine was facing.

These are just but some of the issues that could cause your Mercedes not to start, but make up a large percentage of the reasons why Mercedes won’t start after replacing battery.