Active light system inoperative message turned on?

GUGA TODUA

MEMBER
2014 MERCEDES BENZ E350
3.5L
6 CYL
2WD
AUTOMATIC
100,000 MILES

When I bought this car, the right headlight was not working. It's a full-led and only LEDs were working.

Then I switch the sides of control modules on the headlights.

Now the left headlight was not working. Then, I tried to disconnect and reconnect the cable to the headlight, and it started working.

But I have another issue. I'm constantly getting a message:
"Active light system inoperative".

I did get that message, but the lights were working. Now, the left headlamp doesn't work anymore, connecting and reconnecting the cable sometimes helps.

Since this was happening to the Right one and now the left one, I assume it is a problem with a control module.

My question is, does the side of a control module matter and should I replace it?

2 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

So, this will happen when the control module goes out, when you unplug it, the system will reset. Causing the lights to work again. I would replace the headlight module with a new unit, this should take care of the problem, also, a CAN scan could help us as well. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

Here is how to change out the headlamp module and the headlight system wiring diagrams so you can see how the system works. Check out the images (below). Please let us know what happens.

Images (Click to make bigger)