Help Fixing rear turn signals to blink amber ?

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Mimark

Member
Joined
May 28, 2015
Messages
9
I had noticed, much to my dismay, that our US spec car has red rear turn signals.
I scoured through videos of European spec cars, and finally found one brief shot of the rear making a turn with the amber light. Went outside to look at the tail lights today, and sure enough, all of the amber LEDs are right there, just itching to be used to safely indicate turn intent.
My Audi A6 had the same problem, for which there were a few forums describing the fix. Ten minutes popping Amber bulbs into the blank sockets, and a quick vag-com code rewrite to turn on the Rest of World lighting configuration, and the car is once again safe to drive.
I can only assume that this can be easily done on the Benz also, but I'm new to the MB arena, and have no idea of the equivalent code tools. All I've turned up so far are $5k systems.
Anybody know how to code these things for a reasonable price?
 
I haven't found anyone (so far) that has a VAG-com equivalent cable for our cars, and I'm not holding my breath that one will ever exist. Have you gone to your local Mercedes dealer and asked if they can program the lights for you?
 
I thought MB sold a B-class gasoline version in Canada. Any chance the parts are compatible?
 
Other than the battery / powertrain...it is the same car that's sold in Canada. That said, there is "gateway" software that allows the Tesla electronics communicate with the Mercedes electronics. Personally, I wouldn't risk programming or coding anything through the OBD2 port with an aftermarket diagnostic scanner. If the rear taillights are re-programmable, I'm sure your authorized Mercedes dealer would be happy to oblige (for a price of course).
 
Just for fun, I took apart the tail light cluster, to check how the lights are wired. I noticed that there is power sent to the upper outside lamp, and the neutral is shared with the wires going to the non-functioning amber LEDs. I soldered a jumper wire on the positive lead, and blink goes the amber!
....only problem is that now that the circuit was shared, the turn signal also lit up when hitting the brakes. Not what I was going for.
I'm almost positive that MBUSA would not reprogram it, because a) they would know what I'm talking about, and b) it would technically not comply with the out of date Federal standards, so I may look to an independent shop to fix it for me.
 
It's very likely your dealer has the ability to program the turn signal lights to a "euro" spec in 5 minutes or less. If it's important to you, take the car to an authorized MB/EV dealership and discuss it with the service manager. Not all MB dealerships are created equal. Some will probably do it, other's will give you a deer-in-the-headlights look. My dealership was in the latter category.

It's highly UN-likely that you're going to find someone on this (or other) B250e forum that has done this on their own - or even want's to risk screwing up the car's software. There just isn't enough of a customer base to create a demand for retail/OEM OBD2 programmer, and even if there was, you could expect to pay ~$300 for it. I have the Ross-Tech VW/Audi/Porsche solution. It's fantastic, and allows me to program 100's of options for all those cars.
 
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