Hello to all,

This morning, frightening problem with my 2011 GL350. The vehicle starts but I can't put it in gear and there are all these lights that come on and flash... (see video). I disconnected the battery hoping to reboot the computer but it doesn't seem to work.

Has anyone experienced this before? How did you fix the problem?

 

"Frightening" might be more accurate than "freaking"!

Was it only a short time period that you disconnected the battery? Try disconnecting it for an hour (just the negative cable is all you need to do). While it's disconnected, measure the volts directly at the battery. How old is it? You could have electrical issues with the various SAM units (electronic control units) or wiring issues, but it's good to try the easy things, first. You should be able to get your voltmeter probes on the aux battery, too - check that voltage, as well.

How long have you had the vehicle?

 

Hello Dennis,

Thanks for the advice. I disconnected the negative terminal of the main battery about an hour as suggested. Before reconnecting, I measured the volts; the main battery is at 12.26 and the auxiliary battery is at 12.48 (I did not disconnect the auxiliary battery terminals though).

I reconnected the negative terminal of the main battery and restarted the vehicle. The same messages come back but I was able to put it in forward gear and reverse.

I have had the vehicle for almost 2 years and the main battery was changed in October 2020 (Motomaster Eliminator AGM, 850 ADF).

What are you thinking now, what are your tips?

Thanks for the help

 

Hi Alex. I'm by no means a "pro" at electrical stuff, but I know enough to get in trouble

12.2V is WAY low. You might have an excessive draw somewhere to take a relatively new battery down to that... or the battery could be faulty... or the alternator could be bad (but that usually gives you a red light that you would have already seen). The reason you could shift was because the aux battery is still somewhat decent... although even that voltage is low. All kinds of electrical gremlins happen when V is low... especially on highly electrical sensitive vehicles.

Start by using a decent charger and see if the main battery will take a charge and hold it. Then load test it. Try the aux battery, too. You're probably due for a new aux battery (maybe a new main battery depending on results). HOPEFULLY this is the problem

Was the car sitting unused for a long time?

 

Try a fully charged main battery as well as a fully charged auxiliary battery.

this behavior is that of a dead or dying battery.

 

Hello Dennis,

Thanks again for the advice. I have installed a battery charger and will let it run for a few hours before testing again. It said 70% charge when plugged in, so the main battery seems to be losing charge slowly. We'll see in a few hours.

In the meantime, I contacted a non Mercedes garage (but specialized in Mercedes) where I have my regular maintenance done and they know this problem well. It seems that several customers had to put under warranty the rear blind spot detection system. Mercedes made a massive recall on this particular point.

I contacted a real Mercedes dealer who confirmed that if I had false blind spot alerts lately that could be the problem. And yes... for a few weeks the car was alerting pedestrians or cars for no reason... with the weather and the dirty roads these days I thought the sensors were clogged. The only thing is that the warranty extension for this problem by Mercedes was 10 years from the date of installation... this date has passed since last year... so the repair would be at my expense. The dealer suggests that I first validate that this is the case by disconnecting the blind spot sensors that are in the rear bumper on both sides.

I will work on these two solutions and will keep you informed.

Bye

 

See you have a malfunctioning system maybe it’s the Blindspot, but it’s a current draw the depletes your battery on your part for a while and then you get that kind of behavior.

the clock winding is a dead giveaway.

 

Hello everyone, little update of my research of the weekend... the two batteries have been fully charged and analyzed. They are close to 13 volts so still in excellent working condition.

I easily disconnected the two blind spot sensors at the corner of the rear bumper and the message was still present. Not having access to the two sensors in the center, I set out to detach the rear bumber completely. By disconnecting the main wire cover of the 4 sensors (which could have been disconnected without undoing the bumper because the cover is hidden and accessible in the wall on the driver's side), magic... the problem disappeared.

So I ordered 4 new rear sensors and hope it's not the management module or the wiring... we'll see.

 

Since you have a battery draw you might have a pinched wire in the harness to that system. If you didn’t already go look around the areas you disconnected.