I just started having an issue with the high beam assist in my 2012 E350. I have the P2 package with bi-xenon lights and the passive driver assistance.

With the light switch in auto, the low beams come on at dusk as they're supposed to, but with the turn signal stalk pushed forward instead of the indicator on the dash showing "A" and the high beams turning on and off automatically, the indicator turns blue and they turn on and stay on until the stalk is pulled back to the middle position. Basically, it behaves like a car without high beam assist. I did double check the settings and the system is enabled. I also tried disabling and re-enabling it.

I scanned the car and have the current code in the multifunction camera module:
C14687 Communication with the central gateway has a malfunction

The CGW has the following:
U103711 Front end CAN communication has a malfunction. There is a short circuit to ground.

Both headlights have historic codes:
9004 The state of circuit 56B is unreasonable
9067 No CAN data was received from control module CGW
906C CAN fault

I have no error messages showing on the cluster, and my lane departure assist "seems" to work properly. The lines on a lot of the roads around here are in pretty rough shape after the winter, but on roads with clearly visible lines I see the indicator in the cluster turn green above 40km/h and the "stick shaker" activate when crossing the line without the turn signal activated. This tells me at least part of the multifunction camera is working?

I cleared the historic codes from the light assemblies and I'll scan the car again tonight when it's dark out and see if they come back. As mentioned, the lights are operating normally with the exception of the high beam assist. The lights are the factory units and there is no history of front end damage.

Just looking for some suggestions on where to start troubleshooting and if anyone has a diagram of the front end CAN bus that would be helpful. I do have a bad blind spot radar sensor, and it's bad to the point where my scan tool won't even recognize/talk to it. Could that be introducing errors on the CAN bus?

 

You're in a good spot with your CAN bus survey. Basically you're asking for help to locate a module that may have gotten soaked and now disrupting network.


To progress you can read diagrams to understand bus inter connections or you can do visual inspections for damages.

Front/Rear bumper area is exactly where road projections penetrate into modules.

I am totally unfamiliar with automatic headlights. HL do have a built-in local controller module over LIN or perhaps CAN for Xenon.

One of your fault calls for a "short circuit" condition... exactly what a soaked blind-spot module does!


Go ahead unplug known bad one and inspect/silicon others connectors.

Then clear + rescan for changes.
🤞

 

I cleared all of the historic codes earlier just to see what would come back after dark. This evening when I started the car and pushed the stalk forward into the auto/high beam position, sure enough the system is working as designed. Covering the camera to simulate darkness triggers the high beams, uncovering the camera dips the lights again.

i also did some further troubleshooting of the CAN bus issues. Starting with the obvious, I opened up the first aid kit compartment to access the rear bumper harness and unplugged the white connector for the radar sensors and cleared all codes again. After restarting the car and driving around for a bit, I did another scan and there are no CAN bus related codes. It would appear that the failed blind spot radar was causing a short to ground and maybe some other interference on the CAN bus. So far with that connector unplugged the car is happy and because the radar and parking sensors use separate plugs my Parktronic is unaffected.

Only one fault remains in the multifunction camera module, the window heater is showing an open circuit so the element is obviously burnt out. How long it's been like that, no clue.

The stored codes in the headlight assemblies are probably from a low voltage event, I'm thinking where the car sat for a while in the airport garage a few weeks ago. The live data shows all voltages are normal.

 

You have all your "T's crossed" with minimal pain!
Such a great car now with BS module disruption canceled.


I know the MFK camera has a defroster network on the windhield. I bet it's the MFK solderless connections that are asking for attention over long summer days. It also acts as a camera heater in winter connected though the MFK module.

It may also be the painted GND Post at footwell I believe. Double check exact GND source or go ahead clean the paint out.