I have a new to me 2004 E320 and I have two key fob remotes, one with good range and one with terrible range...

I have replaced the batteries in BOTH remotes. One will unlock from 20 to 30 feet away (or more), the other one won't lock or unlock unless I am 1 foot away...

At first I thought maybe I had a bad batter in the remote with bad range, I have swapped the batteries with the other remote, and the "bad" remote still has terrible range, regardless of the batteries.

On the bad remote, the red light blinks every time I push a button, and it will unlock and lock the doors, but ONLY when I am 1 foot away? The other remote works fine... The problem is not affected by switching batteries. I have removed the circuit board and didn't see anything unusual (not sure what I thought I might see, but seemed like a logical thing to do).

Is it possible that the bad remote is just defective??? I have a spectrum analyzer at work and will take both remotes to work tomorrow and compare the signal strength coming from the two remotes (but I assume the bad one will simply be a weaker signal...).

Any suggestions? I have an appointment with the dealer (for SBC), I'm tempted to ask them to look at the remote, but I assume they will simply say I need a new remote...

Seems very odd? Any thoughts or suggestions would be appreciated.

Thanks

Lee

 

Pull circuit board inspect solder points, etc. if fine, clean and reinstall. No improvement you may need new key given circumstances. If dealer confirms such call several dealers to comparison shop see if your dealer will match lowest price.

 

@konigstiger As always, thanks for your advice. I did a quick look at the solder joints yesterday, but didn't notice anything. I will do a closer inspection tonight.

I did test both remotes with a spectrum analyzer, and the problem remote puts out a much much weaker signal compared to the good key, which tells me there is definitely something wrong with the transmitter part of the key...

I'll do a closer inspection of solder joints and see what I can find.

Thanks again, any other input is appreciated.

Lee

 

FIXED...

Just to close this out, as originally stated, one of my key fob remotes would only lock/unlock when about 12 inches from the car (and only from one area on the car, between the left side front and rear doors). Other than that, the key worked fine and would start the car, etc. Just very very poor remote range.

I did not find any bad solder joints or components that looked bad on the key fob circuit board, regardless the transmitter function of the key remote was definitely not working. When looking at the RF signal coming from the remote using a spectrum analyzer, the signal was not strong at all (even with new batteries) compared to a the other good remote.

According to the thread below, all of programming for this key resides on the "NEC" chip on the circuit board, and can be swapped to a new key board (the thread below describes this for updating the older plastic style key fob to the newer style fob; note that I believe this does NOT work for keyless go):
https://mbworld.org/forums/audio-ele...-retrofit.html

I believe @MacVidMB-V8 offers this "chip swap" to the newer style key fob on ebay as a service.

However, I have a buddy at work that is fantastic at surface mount soldering, and has the right equipment (not your typical soldering iron)... So, I bought a used key of ebay ($20, same plastic style as original), and had my buddy swap the "NEC" chip on the key fob circuit board (basically following the instructions in the thread above, but using an identical plastic style key as a donor key). Now the key from ebay has my old chip, and everything works perfectly!!!!! Remote has normal range, and it starts my car just fine.

However, I don't necessarily recommend that you try this on your own if you don't have the skills/equipment, etc. and you should proceed at your own risk knowing that you may be going to the dealer for a high $$$$ key replacement if it doesn't work (or if you buy the wrong donor key)... If I didn't have someone local who could change out this chip, I would have had @MacVidMB-V8 do the swap via ebay service (I believe he supplies the new style fob (albeit second hand) as part of the service)! In fact, I kind of wish I had gone that route anyway just to get the new style remote (I hate the buttons on the all plastic style key...)...

Regardless, my key remote is working now!

Lee