eric_in_sd

I was tearing my hair out in frustration that the key fob was so lame. I could have even slightly drained 2025 cells in it, and it wouldn't quite work. I had to be on the driver's side, etc.

Then one of the two key fobs would not work unless I disassembled it and held the PC board against the battery holder. Otherwise, supremely aggravating; I could feel the buttons click but no flashing red LED and certainly no response from the locking system.

Other guys have gone so far as to jam 2032 batteries in there.

I had noticed that the gold contacts on the PCB were rubbed by the chrome plated battery holder terminals, so much that the gold had rubbed off the PCB. I figured out that this was causing the dodgy contact.

I solved this by laying down a top coat of solder. Assuming you have a soldering iron and some regular rosin core solder, it is easy. Solder just loves to stick to gold. Just wet the soldering iron tip with solder and wipe along the contact - not across them, or you will probably make a solder bridge between contacts. My soldering iron has a flat tip, but because solder loves gold, this should work with most any tip as long as it is clean enough to have a fully tinned tip. Just don't use a high wattage soldering gun or something reckless like that; you'll roast an expensive coded PCB.

Scrape with a toothpick (not metal; don't want to damage the plastic top coat) if there are any solder whiskers around the pads.

Here is the finished product. Not the prettiest soldering job, but it both repaired the non functional PCB and improved the one that wouldn't work with even slightly drained batteries.



Success. Feels good, man. Praise God.

BlackML550

Great post. Wouldn't it be brilliant if everyone posted their solutions like this?

eric_in_sd

Yeah most of the time doing work on these things is like being raped. You just want to go home, take a shower, and try to forget it happened.

Diamond Dave

Agree with the sentiment. What I've seen is a very loud cadre of people that are brainwashed into "if you didn't buy that from the Mercedes dealer, you are ruining your Mercedes". A few of us are in there getting our hands dirty and it is refreshing to see people pushing boundaries.

BlackML550

With so much chinese garbage out there to buy, only for it to fail, I get it. Ive rarely had to buy anything from MB, so I can only assume some people don't know where to look to find decent quality parts.

juanmor40

For example, the AC compressor's clutch magnet. MB requires a full compressor replacement (at least on the W212 and W166), while the compressor is just a Denso part. Toyota sells you the clutch magnet by itself. A $1000+ AC fix for less than $100.. Go figure.

eric_in_sd

Yeah, I get it too. It takes work to find that middle group that is just as good if not better, and steer clear of the Chinesium, but boy does it pay off.

The irritating thing is that people think the MB assembly line sprinkles magic dust on the parts as they go through. Sadly, vehicles have become largely undifferentiated under the hood; I saw a Toyota ECU and it looked an awful lot like the Bosch unit we have. Not saying it is the same, but MB fabricates precious little of their own parts; I wager it is mostly the brutish stuff like body panels, interior, engine blocks. Maybe engine internals are unique; certainly the crankshaft is but the pistons, rods, bearings could be shelf parts.

I woke up to this way back, when I was admiring Volvo's sodium-filled exhaust valves, and a race type guy tooked at me funny and said, "You can get Silite valves." Very little anyone does is proprietary.