Has anyone had issues with the turn signal switch sometimes not working properly? It has started to occasionally not detect the switch being used, so no way to signal other than with hazard lights.

I'm hoping that it just has some dirt on the contacts which can be cleaned, otherwise the entire Multi-Function Switch assembly has to be replaced.

Update: Xentry says B178F00; seems like the usual answer is to replace the entire thing, I'll try a repair before throwing $500 at it.

 

I occasionally get this problem, ever since I had my MBZ dealer replace the OEM 4 Spoke wheel with an updated S spoke AMG wheel. If you turn off the vehicle and turn it back on, the signals will work again. In my case, it can go months without ANY issue, then I'll have a week (like this week) where it's a constant and VERY annoying issue.

 

There was one day last week when it didn't work at all, then I cleared the error code and it has been fine. Feels more like a software issue than a hardware/electrical issue.

 

It kept getting worse so I replaced the steering column module this week and it solved the problem, here are some notes while its fresh in my mind:

I had some uncertainties going in, but decided to proceed anyway and these were mostly resolved:
1) First time removing the airbag is a blind operation, but basically there is a "channel" inside the steering wheel, so if you insert a flat-head screwdriver parallel with the plane of the steering wheel and push it on the spring you'll see the air bag pop out. You should feel some soft resistance, if you bump something firm then its in the wrong spot.
2) Steering wheel bolt - I didn't know what it would be, turned out to be a big hex which I didn't have (slightly larger than 3/8), but a T55 torx worked. WIS says to replace the bolt, I just put fresh loctite on it, might replace it in the future. Its on tight, I had to use a 1/2 breaker bar to remove.
3) Module's connector - it has a self-destructing tiny clip securing it in place. Best to have a spare handy, I ended up carefully super-gluing it and reused it.
4) Programming - I was concerned it would require online coding, but it just worked automatically without any xentry programming.

Steps:
1) Set wheels straight. Move steering wheel into a mid-height position, and into the dash a bit as it will give you slack on the module connector.
2) Disconnect negative cable on primary and aux batteries
3) Wait a few minutes, remove airbag. Be very gentle with it, please be safe, it has explosives, and absolve me of all responsibility in writing, with a notary, prior to starting this.
4) Remove steering wheel, get helper to counterhold if you're having trouble breaking the bolt.
5) Remove module after unclipping the soft cover
6) Install new module, unclip the red shipping retainer prior to replacing the steering wheel.
7) Reverse steps 4-1



The old clip, I couldn't even read the numbers on it, but they weren't in a typical part-number format
Edit: the clip part number is A0008230245, thanks to Yeffsy for ordering it to confirm (reference post).

 

Were you also getting a warning about Blind Spot Sensor being inoperative message at the same time your turn signals were acting up? Mine seem to be associated. I am wondering if the part of the switch in the steering sensor that is going bad thus the truck doesn't know the steering angle and throwing the warning about the Blind Spot being in operative. I plan on replacing the switch anyway just wondering if I need to find another problem

 

Yes this would happen. And on a rare occasion it wouldn't shift without power-cycling the car.

 

just replaced the failing unit with one from a salvage yard that came off a 2014 ML. Took maybe 15 minutes and only cost $150. Working perfect for now.

 

Thanks for the instructions! I am having the same problem on a 2013 GLK 250. The turn signal will stop working after driving for a while. Starts working again after turning the car off then on. Did you replace the entire steering column, or just the small module? What was the part number you replaced?

 

The entire assembly on the X166 chassis comes a single component. If you'd like to DM me your VIN, I can look up parts details in EPC for you.

 

Thanks Mekantor. I pm'd you my VIN. Whenever I tried to search for the part, it says "discontinued". So what's a relatively modern (2013-2015) GLK owner going to do if they need to replace the steering column assembly?

 

I am now getting "Active Blind Spot Assist Inoperative" a several times a day that it is dangerous.
I am going to try to change the turn signal control module. Hope this solves my problem.

 

I replaced the turn signal control module on Sunday and so far I have not seen the "Active Blind Spot Assist Inoperative" message so far, knock on wood.
The message started showing up during some long distance trips so until I complete one of those, I am not certain if this replacement worked but so far so good.

Here are some info I would like to share from my work.

@mekantor's instructions above were valuable so thanks to him. I found a video that helped me and here it is: . Lars did a great job.

I never open up my battery before and learned that it was replaced once so it was good to know. Disconnecting the main battery took me like 30 min to get to it. One tool that came in handy is the plastic pin puller. There was a plastic pin that holds the blower outlet and the battery cover. Disconnecting the auxiliary battery took me like 15~20 min because I watched one video that told me to get to the back panel with torq screws but later realized that it is not really needed. You can just move the padding down to get to it.

As mekantor mentioned, took me almost 30 min to take the air bag out. I couldn't find the metal spring to release. After watching several videos and studying the angle, I was successful. Don't force anything. Once you find the spring mechanism, it pushes in without much force.
I also had to use my breaker bar to unlock the main steering lock screw.

I broke the small clip in mekantor's picture as well, but decided not to put it back in because even without it the connector is pretty secure with a locking mechanism.

Took me total of about 4~5 hours.

 

@gladerider Have you had any more problems since replacing the turn signal module? What is the part number of part you replaced? Having the same problem, thinking about trying to fix it myself.

 

hi Jason.

so far it has not happened again but my problem started to happen during long distance trips and i have not had a long distance trips since replacing so the jury is still out

i tried to find the part number but i cannot seemed to find it. some numbers on the part doesn't show up on google. what i did was to find a used part on ebay with the entire control module. i just took the signal module off of it. hope that helps.

 

@gladerider and @mekantor I'm having trouble understanding what part you two replaced. Is this it?

MERCEDES]W166 X166 ML350 STEERING WHEEL CLOCK SPRING SWITCHES GEAR SHIFTER OEM


A 166 900 96 00, A1669000108 A1669000703

 

Yes replaced that entire thing, should match the part number based on your VIN or an updated replacement part. Be careful because there are lots of trim and other options for it. I have an EPC subscription so if you're unsure then DM your VIN to me.

 

Thanks @mekantor!

Seems the part number of my car is A166 900 04 08 9051 (includes all options, color: black) for anyone who finds this thread and needs to know. Found online for $419.21 here: Multi-Function Switch - Mercedes-Benz (166-900-04-08-9051)

 

hi Jason,

sorry i just saw this.

i just replaced the top signal stalk not the entire thing. but technically, either should work.

 

hello I have same issue can you help me with part number base on my vin DA208244

 

For that VIN it is showing A 166 900 04 08 9051

 

Mekantor would you be able to help me with the part number for my vin 4JGDA5HB4EA330206

thank you!

 

Hi, for this car the part is A 166 900 00 08 9051. I might have to replace mine AGAIN, yesterday it refused to shift out of Park, then went back to normal on its own. So many people have issues with this same component, if you can't signal a lane change or change gear it should just be a recall.

 

I encountered the same issue and could you please help check the part? The VIN is 4JGDA5HB3EA296775. Thanks!

 

Here you are, A 166 900 01 08 8N85, good luck!

 

Many thanks for the information. Another question, where do you usually buy the part? The manufacturer's price (from mbparts.mbusa.com) is about $665. I found there are a couple of OEM parts selling online at ~20% discount (e.g., www.oemvehicleparts.com), but I am not sure how good they are.