geekoncall

Hi guys, I have 2014 ML350 with about 146K on it.
I was getting blind spot assist inoperative for a while. It was intermittent, will come and go (noticed yellow triangles are lit on side mirrors all the time). Battery died few weeks ago. Bought a new battery from Costco (both main and auxiliary) and had it install at Canadian tire.

Now blind spot inoperative message is back as well as pre-safe functions limited, see owner's manual message. Both message show up as soon as I start the car, If I press ok, they disappear from dash but remains in the warning message but I can drive without any issues.
- Is this safe to keep driving with these 2 functions not available? I am in the middle of a long drive, wont able to get back soon. I read few post where people with same issues losing power in the middle of highway or car entering in collision mode, sounds scary.
- I was checking front bumper grills for radar sensors and noticed, my front drive side has no radar sensor unit at all but front passenger side grill has radar sensor unit in it. Is this supposed to be only one sensor unit on front? I can see back bumper has two, one on each side.
- Do all radar sensor units have same model in a vehicle, front and back? in my case, I can see front one is A0009054603
Thanks a million in advance for your input.

NNNN

I think the car need to be scanned by scan tool to see what item is defective. There are 3 sensors at the front. 2 short range radar behind the bumper and one long range at center behind the Mer Star. Any one of these not working will make the car shut down the presafe function. You need to narrow down which one have issue and replace that sensor only.

geekoncall

Thank you. yes, I will take for service as soon as I am back. I noticed now when I start the car (on key position 1 and 2), yellow triangle turns orange like blind spot is active and working but as soon as engine starts, I get blind spot inoperative message and orange triangles return to yellow. Pre-safe warning is gone somehow and I was just able to disable (on key position 1) blind spot too, so at the moment, no error or messages

NNNN

Base on your description, blind spot radar may working normally. Defective part will be either long range or short range radar at the front. Before they completely not working, they can work intermittently for a while. In my case, once replace the defective part. It works normal after few drive. Make sure you scan or ask someone can scan for you so you can replace the only defective part. When I brought mine to workshop, they suggested replacing many different part that would cost a lot of money and resolve nothing.

geekoncall

Thank you for suggestions, appreciated.