Tail lights don't come on at night when in AUTO

[Sparcky]

2023 RAM Laramie Sport - Last night, I found out that my tail lights at night were not working for some reason. They were working before, as I pull a trailer occasionally and check when I connect it. I usually keep the selector switch in AUTO for lights. Headlights work, high beams when in Auto don't work either. Brake lights work fine.

When I manually turn on the headlights, they work and so does the rear tail lights, as well as high beams.

I just checked in the daytime, when in AUTO, I cover the sensor and it seems to work, display dims like it should at night. head lights work, but no tail lights.

This kind of rules out the sensor and the switch in my thoughts.

I disconnected the negative terminal on the battery, and reconnected. Nothing changed.

Any thoughts? I do have AlphaODB, and used it for other functions before, but wasn't using it when this happened, is there a setting that I can check?

 

[Sparcky]

Bump

 

[kapinallinen2]

Bump

Could it have something to do with DRL setting? Other than that, no idea.

 

[FastBlackRam]

There is a Body Control Module (BCM) that I think may control all the lights. I had one fail for me where the DRLs on one side and the fog light on that side wouldn't work. They replaced the headlight assembly and the foglight (all LED) and the problem persisted. They then went to the BCM and it fixed it. Under warranty.

 

[kapinallinen2]

There is a Body Control Module (BCM) that I think may control all the lights.

That is correct.

 

[Sparcky]

Are the BCM settings in AlphaODB? maybe it lost its programming? Or is it likely a dealer only fix?

 

[Jimmy07]

Are the BCM settings in AlphaODB? maybe it lost its programming? Or is it likely a dealer only fix?

Is this a Canadian truck with no off “O” position on the headlight switch?

 

[Sparcky]

Is this a Canadian truck with no off “O” position on the headlight switch?

yes canadian truck. No "0" off position.

A bit more of an update. Had a trailer connected as I am going sledding, and hit the remote start. All lights turned on with the remote start. Tail lights, etc. Indicator on dash said headlights on. BUT, when remote start cancelled, the don't work. very odd. I will have a chance to go through the DRL programming later today or tomorrow. Hope it's just a setting.

 

[Jimmy07]

yes canadian truck. No "0" off position.

A bit more of an update. Had a trailer connected as I am going sledding, and hit the remote start. All lights turned on with the remote start. Tail lights, etc. Indicator on dash said headlights on. BUT, when remote start cancelled, the don't work. very odd. I will have a chance to go through the DRL programming later today or tomorrow. Hope it's just a setting.

It’s a little goofy how they have that set up to work. Try switching over to headlights on, then verify that all lights are on, then move it back over to auto and re-check the lights (provided it’s dark enough for the lights to kick on).

 

[Sparcky]

It’s a little goofy how they have that set up to work. Try switching over to headlights on, then verify that all lights are on, then move it back over to auto and re-check the lights (provided it’s dark enough for the lights to kick on).

Yes did that. When lights in ON position, everything works. When truck is remote started, and auto light setting, everything works. When truck is started (not remote start) and auto light setting, in dark or with sensor covered, headlights on, tail lights off. Very weird

 

[Sparcky]

So don’t have the solution, but seems to work now. I just added a trailer brake controller this week in the factory location, used alphaODB to program the 3 settings as per instruction here, and suddenly the auto setting works fine at night. Software glitch maybe.