Adaptive Headlamps Warning on

Scott Owner British Columbia Posted   Latest   Edited  
2013 Cadillac XTS 3.6L (3 LFX) 6-spd (6T70) — 2G61T5S30D9112375

This Cadillac had a minor collision repair and both front lamps were replaced with OEM. Adaptive Headlamps Warning on in info center and Bulb warning lamp on. We are at the end of the road for what we should test next. I am writing this for our tech, so any questions please ask me!

Code: U1523 LIN bus 2 lost communication with device 3. This is caused by the right head lamp not talking to the head lamp control module. Data line appears to be working right up to the right head lamp. Visually inspected wiring for damage. Our technician swapped the head lamps side to side to confirm this is a failed head lamp. This vehicle also requires a auto leveling head lamp calibration after the code is resolved. UPDATE: Headlamp was swapped left to right and code still exists for the right side. Wiring was tested at the head lamp and appears fine. Software was updated for the head light control module but did not fix the issue with the module. Technician recommends replacing head lamp control module.

Technician has tested headlamp control module in every possible way. New OEM module installed and programmed, and then a second new OEM headlamp have been installed. LIN line has been replaced out, powers and grounds checked. LIN data waveform identical to left and right side. Left side works normally and is able to be actuated through the scan tool, if you run the Right headlamp through the left LIN you are able to control the headlamp and have no issues with the right headlamp/wiring. Programming software asks for no options, looking at the module wiring different configurations on this vehicle are possible because the diagram says suspension sensors input into the module but on this vehicle it does not have those wires and the suspension control module talks to it (no issues with suspension control module). Unknowns on this vehicle are: 1) what are device 3 and device 4 on the LIN bus specifically. Unable to get that information. 2) Unable to get accurate wiring diagram, colors are wrong on the BCM controlled part of the headlamp. Connecter pin locations are wrong and the headlamp module doesn't have suspension sensors. Technician has tested every wire though and doesn't see anything missing. Technician can only suspect this is a software issue that needs to be addressed at the engineering level.

There is also a code for the Human Interface module (USB port) but we do not believe its related. The B101E (pictured) was set by us and after programming the new module it cleared and did not return.

Brad Diagnostician

There is a ongoing thread about this on the GM Technician forum. GM dudes why above my pay grade have been talking about this. At this point engineering is still looking at this. I haven't see a update on it in a while. That particular vehicle we are talking about is a CTS. What is odd is when I stuffed this VIN into IVH it populated very few RPO's. Seems about ¾ of them are missing. There are…

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Frank Manager

Cannot wait to retire!

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Robert Owner

I do know that before the headlights will pass a calibration, the suspension must be calibrated first.

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Richard Mobile Technician

You have alot going on there. Basics would be a good wiring diagram but I certainly know they have an “Advanced” electrical system that if disconnected from power can have some issues. I wish you the best.

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