Jason Stewart

SYMPTOMS:

• Periodic "Active Blind Spot Assist Inoperative" and "Active Lane Keep Assist Inoperative" warning messages.
• Periodic loss of turn signals

REMEDIATIONS (already tried):

• Cleaning front and rear parking sensors
• Cleaning front-facing camera
• Replacing broken front star emblem (part #164-888-04-11)

RESULT: original symptoms persist.

DISCUSSION: I've read anecdotal reports of this combination of symptoms indicating a problem with the blind spot radar sensors in the rear bumper (water damage from broken casing). See this MercedesMedic link.

QUESTION: Has anyone else had this problem? If so, what was the cause and your solution?

EDIT: I'm pretty sure this is a turn signal module problem (described here).

mtm

Take a look at this thread - same symptoms, required replacement of the combination switch.

https://mbworld.org/forums/gl-class-...acting-up.html

Jet Wrench

I had the same symptoms on my 2012 GL450. Turn signals, blind spot and fuel gauge inoperative. I found the reason as to why it failed as well. If the rear windows are left opened and it rains, water will enter the vehicle and soak the SAM that resides at the rear right tail light. Always make sure the windows are closed (lowest switch on the driver window switch panel) when exiting the vehicle. The switch is easily bumped when driving. The new module will have to be programmed by MB for all systems controlled by the module.

BlownV8

The rear taillights are a known water entry point. Yes, most likely SAM is sitting in water or it's been exposed to water and is now corroded.

mikapen

In order for the rear SAM to be under water, it would take about 5 gallons of water, sloshing around in the rear quarter panel. And it would have filled the spare tire well and soaked the carpets throughout the car. Now, that's a bunch of water to enter through a taillight! Unbelievable!!!
So the lesson is - if your feet get wet every time you get in your car, be sure to check your taillight - just sayin'.

BlownV8

There is a difference between sitting in water, what I said, and being immersed in water. With that said, I have had a SAM almost covered in water and, yes, it was gallons but was from leaving the window open. Very expensive mistake.

mikapen

Sorry about my flippant response.
In this case I am having trouble visualizing the waterway from door to rear quarter, where the SAM resides. Is the rear quarter window operable (I don't have a GLS)?

arsupisemnet

Had it in the beginning. There is a steering wheel control module which cause turn signals to disappear...

arsupisemnet

Had it in the beginning. There is a steering wheel control module which cause turn signals to disappear...
Similar case
https://mbworld.org/forums/gl-class-...noperable.html

BlownV8

Yes, the rear quarter window does pop out.

Jason Stewart

How do you access the SAM module? Sounds like something I could easily check... thanks for the tip!

Jason Stewart

This is strange, but I found that when I get the “Active Blindspot assist inoperative“ or “Active Lane keeping assist in operative” messages (and those systems stop working) that they will immediately start working again if I just turn on the right turn signal then the left turn signal (in quick succession) while the vehicle is in Drive (D).

I’m still not sure what the root cause of this problem is, but this interim fix is unobtrusive enough that I think I can stretch out my next dealer appointment.

garysymons

I can't believe it. Sitting in a carpark with this problem. Tried your fix and it worked! Ta heaps