Light won't turn off

[bmchuckleyou]

Hey guys,

I have a strange issue.

I have a rear LED taillight that is constantly illuminated. I've attached a photo to show what it looks like.

Yes, I have searched the forums and no, it is not the safety feature associated with flipping the stalk.

Disconnecting the battery does not reset this.723136

Any thoughts?

[TiesTorN]

https://www.bimmerforums.com/forum/showthread.php?2471740-Light-Problems

[JimLev]

Make sure your directional switch lever is in the center position.

[bmchuckleyou]

Make sure your directional switch lever is in the center position.

Thanks Jim, but I'm pretty sure it's not the directional switch lever - that's what I was referring to when I wrote "stalk".

TiesTorn - thank you also. I don't believe it is the LCM because it's a fairly low mile replacement.

I did notice the connector pin for the LEDs may be a bit corroded, but I thought that would be more likely to cause the light to not work - instead of stay on constantly.

[TiesTorN]

TiesTorn - thank you also. I don't believe it is the LCM because it's a fairly low mile replacement.
age is a more important factor in these modules rather than mileage so it doesn't matter much that it's a low mileage replacement. it can still go bad.

[Toby B]

what happens if you turn off all the taillight self- checking?

t
doesn't think that's it, but is just curious.

[crdiscoverer]

Did you get the car with this problem? If not, when did it start? Any recent things you replaced that could've caused this (eg. new battery, LCM, etc.)?

Do you get bulb out errors in that corner? Do all other bulbs in that tail light work fine? First thing to do is inspect the wiring. What you have is a parasitic power draw that was nice and evidenced itself. Sometimes it's just a matter of cleaning a corroded ground terminal.

Unscrew and unplug both tail lights, swap them. The connector is the same and you don't need to mount them, just see if the issue goes away. If it does then you simply need a new tail light.

[bmchuckleyou]

There has not been any recent work that could have any connection.

This issue just came about randomly and now it seems to possibly be intermittent.

Unfortunately, I don't think I can switch with the other side to test. This is the centre light on a touring - so its on the hatch. The light connection is directional - as can be seen in this photo stolen from a member of another forum ( thanks Jacce1971):

https://www.bimmerforums.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=192 0,fit=scale-down/https://www.bimmerfest.com/attachments/suunnitelma-jpg.1027072/

[crdiscoverer]

Ah! Didn't notice it was the touring hatch light.

[bmchuckleyou]

So the mystery deepens....

After driving the car all day without much problem, I just went out to move the car into the garage.

After starting, I notice the red battery light illuminated.

Low OBC secret menu - and I see the voltage is sitting at 11.9 with the car on.

I have to kind of drive around the block to get to the garage, so I give it some pep to ensure I get to the garage asap. The voltage is only going to 12-12.1 with some right foot.

I think I'm going to have to check for loose connections and then maybe look at the alternator/ voltage regulator.

[bmchuckleyou]

Just updating this to add to community knowledge.

A replacement alternator has gone in and the taillight is no longer on.

So it does appear that perhaps there was a voltage leak from the alternator.

Only problem now is that the replacement alternator (used) has a bearing noise..😡

[bmchuckleyou]

Also,

Replacing the alternator appears to have fixed a longstanding battery drain that I've been dealing with, so if you also have a battery drain that you can't find by checking the fuses, it just might be the alternator.

[crdiscoverer]

Interesting. Thanks for the updates. Sucks about the bearing.

[bmchuckleyou]

Ok. So, I spoke too soon.

Issue is back 😡

[TiesTorN]

I was gonna say that alternator has nothing to do with that light and it's probably gonna come back but didn't wanna sadden you lol.

it's your lcm.

[KeysCoupe]

The touring tailgate wires run along the tailgate hinge under a plastic cover, and they are known to have issues with insulation and wires breaking from flexing near the hinge. Broken or cross-shorted wires could possibly be causing your intermittent light issue.
-Donny

[TiesTorN]

Broken or cross-shorted wires could possibly be causing your intermittent light issue.
-Donny
no that won't cause lights to stay on when the car is off.

[bmchuckleyou]

I was gonna say that alternator has nothing to do with that light and it's probably gonna come back but didn't wanna sadden you lol.

it's your lcm.

I would assume there would be a constant current if it were the LCM, no?

There doesn't seem to be any current when the bulb holder is disconnected.

The led bars only light up when the "led bulb" is plugged in.

I will add - the lights don't appear to be fully lit up, it's just enough to be noticeable when it is dark out.

[TiesTorN]

I posted a link in my first post, there you can see that we discussed about bad capacitors. you may have the same problem.

[seagreen323i]

Check taillight ground, brown wire. Lots of weird things happen when that ground is funny.

I had a periodic issue with my turn signal stalk failing, causing the courtesy lights that trigger when you flash the high beams to randomly illuminate and kill the battery. If it's periodic, I'd check that.

Unfortunately, miles are not what kill the LCM, it's age and water intrusion. Possibly, you had water mess up your previous one and this one also got messed up?

Sent from my SM-S901U using Tapatalk

[bmchuckleyou]

Check taillight ground, brown wire. Lots of weird things happen when that ground is funny.

I had a periodic issue with my turn signal stalk failing, causing the courtesy lights that trigger when you flash the high beams to randomly illuminate and kill the battery. If it's periodic, I'd check that.

Unfortunately, miles are not what kill the LCM, it's age and water intrusion. Possibly, you had water mess up your previous one and this one also got messed up?

Sent from my SM-S901U using Tapatalk

Thanks, I'll check the ground.

There's been no water intrusion that I know of, at least there's been none under my ownership.

LCM was only changed to go LCM III B to enable celis tail coding.

Just to note - when I got the used Celis taillights, I had to reuse the old original bulb housing, because the one that came with the Celis taillight was so badly corroded, it looked like a nuclear wasteland.

So, when I say there is corrosion on the led bulb connector, it is BAD.

I'm going to try finding a replacement light and see what effect that has.

If that doesn't fix it, I'll swap out the LCM.

[seagreen323i]

I'd suspect corrosion, I've had some weird light issues stem from corroded rear light connectors.

Sent from my SM-S901U using Tapatalk

[bmchuckleyou]

I'd suspect corrosion, I've had some weird light issues stem from corroded rear light connectors.

Sent from my SM-S901U using Tapatalk

Yeah, it's just a shame there is no easy way to just change a bulb in these things.

[TiesTorN]

corrosion also won't cause that when the car is off. it's basic electronics.

[bmchuckleyou]

corrosion also won't cause that when the car is off. it's basic electronics.

I've been looking at the LCM schematics.

There appears to just be one capacitor/ transistor for each side taillight.

If it were an LCM issue, I would expect the outer side taillight to also illuminate, don't you think?

[e32weis]

Amy update on this issue?