[nugent]

I don't know much about soldering but $50 sounds too inexpensive to be true. Just reprogramming alone is more than $50, so I'll disregard that quote. I am thinking more like $200+

Here is the site, FWIW: https://www.autotronics.co.uk/repair-mercedes-a-remote-key-fob-old-style.html

I'll investigate your other suggestions, thanks.

 

[nugent]

Yes, their is one guy... See this whole thread, but read post118 and beyond :nerd

http://www.benzworld.org/forums/c209-a209-clk-class/1575195-diy-new-chrome-key-upgrade-retrofit.html

Have sent a pm to him. Thanks for this and the other links - very interesting and useful. I always try to do my due diligence before posting my own problems, but missed these.

If no luck, I shall try reflowing as suggested. Good thing I have a working key, so no panic.

 

[nugent]

The Thick Plottens

Hi, got your PM.

I would be happy to try to help...

My thanks to you, mrboca, Deplore and MAVA.

My cheapo multimeter tells me there is no resistance when I measure over the solder strips on either side of the coil. Same for the terminals on the front by the IR LED. I can still see the IR blink with my camera, and also the side LED.

Here is where it gets stranger. We recently returned from a 10-day trip. This morning, while I was once again at the car outside, trying the key, the neighbor came over and said that the alarm had gone off briefly a few times while we were away. Each time it had silenced itself after a short time. The car is parked in the driveway.

So something strange is going on. Meanwhile I still have one working key, and one dud.

I am happy to send you the key to fool with, if we decide that it is in fact the problem. Right now I have nothing to lose.

 

[nugent]

No resistance as in dead short or no continuity as in open circuit?

I'll have a look on Ebay for one of these. That way I could either move the front coil/IR assembly to old key or move EEPROM onto new one.

As in dead short, 0 ohm.

 

[nugent]

mrboca, each of the buttons appear to work properly, with a positive "click" and return. I sprayed with electronic parts cleaner and canned air to dry.

Inserting the bare coil end into the ignition slot does nothing.

 

[nugent]

I assume you inserted the coil end fully to activate the switch that activates the transponder coil around the ignition switch hole.

Yes, I did this, few times to be sure.

Further testing of induced voltage or other signals is beyond my capability, I'm afraid.

 

[nugent]

UPDATE: I got 2 used keys off Ebay and Nugent's dead key.

I could find no obvious faults with Nugent's key.

I picked the best Ebay key and moved the EEPROM chip over.

The red light would flash in response to the buttons. With Gen2/Gen 3 keys this has always meant the key was functional.

Sadly Nugent reports that the symptoms have not changed. The key behaves as if from different car. I will add pix shortly.

Thank you for trying. This whole thing is very mysterious. I had a perfectly working key, that suddenly stopped working. There did not appear to be anything wrong, the EEPROM was moved, leds blink, etc. And the spare key is fine. I am out of ideas...

 

[nugent]

Have you checked the IR function of the remote with a cam / smartphone?

Try the following:

Instructions on how to sync Mercedes remote:

Insert the key into the ignition.
Quickly remove key from ignition and within 10 seconds hold down the lock button.
Continue holding the lock button, and at the same time press, the unlock button five times.
Next release all buttons and press the gate/trunk button one time.
Your Mercedes remote should be synchronized. Test to see if lock / unlock functions are working.

Yes, I can see the IR LED flash with a smartphone.

I tried the sync you described, but still not working. But thanks for persisting with me.

 

[nugent]

Well, well, well... Fixed?

After the dealer quoted $300 for a key, my motivation was renewed. I have been trying everything I, or google, can think of to make the key work.

Today I found a slight variation on mrboca's procedure: "Reset your Mercedes-Benz key by placing the key in the ignition of your vehicle while the vehicle is turned off. Do not turn on the vehicle. Press a finger on the "lock" button of your key fob while the key is in the Mercedes' ignition.

Pull the key out of the ignition while continuing to hold the "lock" button down. Continue to hold the "lock" button for the duration of the key resetting process.

Use another finger to push down on the "unlock" button five consecutive times. Keep holding down the "lock" button.

Release the "lock" button. This is the end of the resetting process for your Mercedes-Benz. Use your key fob to ensure it is properly working."

The second time I tried it, I inserted the good key in the ignition, which unlocked. I removed to good key and inserted the non-working one, which unlocked and was able to turn! Removed the newly working key and confirmed that it would unlock the driver door only. I pressed the lock and unlock together to make it unlock all doors - aaand, it stopped working again.

After some cursing, I managed to get it going again with the procedure, and also managed to program it to unlock all doors. So it seems I have a working key again, although I have to say I am leery after my experience. I am still mystified why it stopped working, and also mystified why it started again.

Thanks again to everyone who stopped by to help, especially 93SoCal400E who transplanted the chip.

 

[nugent]

Here we go again

I had not driven my car for more than a week. This morning I went to pick up SWMBO at the airport. I used the refurbished key to unlock and start, and off I went. After parking at the airport, the key would not lock the car. In the ignition - nothing. So I had to lock the car with the spare working key, and use it to unlock again and drive home.

I have not yet tried to resync the key as I thought I'd post here first. Something is funky.

 

[nugent]

Make sure that the batteries make good contact with the battery tray.

I believe the batteries are good and making good contact as I am getting a flash from the LED. In any case, the key should work in the ignition without the batteries.

 

[nugent]

Key was bad.
I believe he acknowledged up front that key may be killed by the procedure. This was my first Gen 1 Smartkey. I'm happy to move to the EEPROM to the 2nd donor key.

The key Nugent sent and the other one I bought appeared to have damage from some over-eager-Einsten jamming the PCB in to the key housing with force.

Anyhow, Nugent is welcome to send key back and I'll either fix bad joint or move EEPROM to donor #2. At that point it would HAVE to be dying EEPROM not erasing/writing correctly.

I'd love to see this resolved. These keys are getting rarer but I'd still like to know them better.

The good news is that I got the key going again by following the re-sync procedure. I don't drive the car often, so wait and see if it lasts.

I had zero expectations about the key ever working again, so I regard 93SoCal400E's efforts as a success. None if this is his fault, and he won't respond to my offers to pay.

Thanks for the offer to reflow the solder, but as it's working I'll hang on to it for now. That may change if your offer remains open!