Accidentally running your Mercedes key fob through the wash can be a moment of panic for any car owner. Discovering your key fob soaked after a laundry cycle might seem like a disaster, potentially costing you hundreds for a replacement. But don’t worry, at keyfobx.com, we specialize in automotive key solutions, and we’re here to guide you through a DIY fix. Before you assume the worst and rush to the dealership, know that there’s a good chance you can revive your waterlogged Mercedes key fob right at home. The key is to act quickly and carefully. This guide will walk you through the steps of Opening A Mercedes Key Fob and cleaning its internal components to get it working again.
What To Do Immediately After Water Damage
The absolute first thing you need to do when you realize your Mercedes key fob has been submerged in water is to remove the batteries immediately. This is crucial. Do not press any buttons on the fob while the batteries are still inside, as this can cause a short circuit and lead to further damage to the electronic components. Think of it as car key first aid – quick action can significantly increase the chances of a successful recovery.
Tools You’ll Need
Before we dive into the process of opening your Mercedes key fob, gather these essential tools. Having everything ready will make the repair smoother and more efficient:
- Isopropyl Alcohol (50-70% concentration): This is your primary cleaning agent. It’s readily available at most pharmacies and supermarkets. The alcohol helps to displace water and clean off oxidation without damaging electronic components.
- Cotton Swabs (Q-tips): You’ll need a generous supply of these for applying alcohol and gently cleaning delicate parts.
- Small, Shallow Container: This will be used to immerse the electronic circuit board in isopropyl alcohol. A small dish or even a clean bottle cap can work.
- Flat Pliers: These are essential for carefully prying open the key fob casing without causing damage. Needle-nose pliers can be particularly helpful.
- Small Flat Knife or Flat-Head Screwdriver: A very thin knife or a precision screwdriver will be needed to gently separate components that may be glued together inside the fob.
Step-by-Step Guide to Opening Your Mercedes Key Fob
Now that you’ve got your tools and acted fast by removing the batteries, let’s proceed with disassembling and cleaning your Mercedes key fob.
Step 1: Opening the Key Fob Casing
The Mercedes key fob casing is typically held together by a combination of epoxy glue and plastic clips. To open it, you’ll need your flat pliers. Extend the mechanical key blade as if you were going to use it to manually open your car door. This will reveal a small gap in the fob casing. Insert the tips of your pliers into this gap.
Gently apply pressure and pry in the direction indicated by the arrows in the image. Work your way around the seam of the fob, carefully separating the front and back halves. Be extremely cautious as you pry, especially near the key blade hinge, as there’s a small spring mechanism that can easily pop out and get lost. Take your time and avoid forcing it open abruptly.
Step 2: Removing the Electronic Board
Once the casing is open, you’ll see the internal components, including the electronic circuit board. Carefully remove the board from the casing. Pay close attention to the battery terminals – these are delicate metal contacts that can be easily bent or broken.
Usually, you can gently push the board from the battery compartment side to ease it out. Avoid pulling or yanking, and make sure nothing is snagging as you lift the board free.
Step 3: Detaching the White Plastic Cover
On the electronic board, you’ll likely find a small white plastic cover. This cover often secures the transponder chip and is attached with epoxy glue. To remove it, take a cotton swab dipped in isopropyl alcohol and apply a few drops to the edges of the plastic cover. Let the alcohol soak for a minute or two to soften the glue.
Next, using your small flat knife or screwdriver, carefully insert the tip between the white plastic cover and the transponder chip. Gently pry upwards to separate the cover. Important: Be extremely careful not to apply pressure directly to the transponder chip itself, as it is fragile and essential for your key to communicate with your car.
Step 4: Removing the Transponder
The transponder chip is the most critical component, as it’s programmed to your specific vehicle. It’s usually glued to the circuit board. Repeat the process of applying isopropyl alcohol around the transponder to soften the adhesive.
After letting the alcohol work for a few minutes, gently slide your small knife or screwdriver underneath the transponder and carefully pry it upwards. Note the orientation of the transponder as you remove it – this will be important when reassembling the key fob. Handle the transponder with utmost care.
Cleaning Oxidized Contacts
Water damage often leads to oxidation on the metal contacts of the electronic board. This oxidation is the greenish or whitish buildup you might see, and it can prevent proper electrical contact, causing your key fob to malfunction.
Pour a generous amount of isopropyl alcohol into your shallow container and fully immerse the electronic board. Let it soak for about 5-10 minutes. The alcohol will help to dissolve the oxidation and displace any remaining water. While the board is soaking, use a fresh cotton swab dipped in alcohol to gently rub at the oxidized contacts and other areas of the board. After soaking, remove the board and use dry cotton swabs to continue cleaning, focusing on removing all traces of oxidation. Allow all components to air dry completely for at least 30 minutes before reassembly to ensure no moisture is trapped inside.
Reassembling Your Key Fob
Once all parts are clean and dry, carefully begin reassembling your Mercedes key fob in the reverse order of disassembly. Ensure the transponder is placed back in its original orientation. Clean any other parts of the casing with alcohol to remove any dirt or residue.
Carefully snap the two halves of the key fob casing back together until they are securely closed. Insert new batteries, and test your key fob. In many cases, this cleaning process is enough to restore your Mercedes key fob to full working order.
If you find that your key fob is still not functioning after cleaning and reassembly, or if you’re uncomfortable performing this DIY repair, keyfobx.com offers professional key fob repair and replacement services. Visit our website to explore our services and get back on the road with a fully functional Mercedes key fob.
