Light Problems

**GZilla** · 01-16-2023, 12:07 PM

So I decided to move my E39 from my driveway and onto level ground since there was going to be rain, it had already rained for a couple hours prior. When I started the car it took 5 seconds for the automatic lights to turn on and the night time orange lights in the interior were flickering. I parked the car on the street and went to sleep. Woke up the next morning and noticed that my driver’s side high beam and passenger side indicator is on. I thought it might have been water damage but the passenger side footwell and floor was not wet. I checked my battery voltage and it was 11.6. I unhooked my battery and charged it for a couple of hours until it was fully charged. The same lights are still on.

I’m guessing this is a common issue that many members ask?

**seagreen323i** · 01-16-2023, 12:35 PM

My father had that issue in his 530, turn signal indicators got stuck on. Was a faulty light control module.

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**GZilla** · 01-16-2023, 12:38 PM

Thank you Seagreen. I will look into it. I know my sunroof drains are cleaned since when I did my interior restoration and had my headliner and cassette off I made sure the pipes were clean.

**GZilla** · 01-16-2023, 11:21 PM

By the way, I did check my floor board and the area where my light control module. There is no water nor is the foam wet. So maybe the light control module took a dump on me at this moment?

**seagreen323i** · 01-16-2023, 11:31 PM

Yep. His just took a dump on him, old electronics. Happened completely randomly, walked outside to leave for work and noticed the drivers rear turn signal was solidly illuminated, no indicator on the dash.

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**E39 Newbie** · 01-16-2023, 11:42 PM

Originally Posted by GZilla

By the way, I did check my floor board and the area where my light control module. There is no water nor is the foam wet. So maybe the light control module took a dump on me at this moment?

The PO of mine had some moron install a crappy windshield that leaked down the passenger A pillar. The LKM got wet and began to corrode. It failed on me, even though I had the windshield repaired long before the module failed. But I looked inside of it and, sure enough, plenty of corrosion at the bottom of the unit where the water would have pooled. So... yours probably did the same at some point.

**GZilla** · 01-17-2023, 09:56 PM

So I removed my LCM. Checked for corrosion and only noted minor surface rust. However, there was a thick layer of dust everywhere, so I used compressed air to blow everything out. I will be sending it out to get it repaired by a service that repairs them. Can I drive my car without the LCM or will it cause the car to bug out? The battery is still unhooked. Here are pics.

IMG_9884.jpg IMG_9885.jpg

**seagreen323i** · 01-17-2023, 10:59 PM

You will have no lights, no brake lights, turn signals, reverse lights. It would be a hazard to drive.

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**GZilla** · 01-18-2023, 05:12 PM

There was a thick coat of dust on my circuit board. Used some rubbing alcohol and a toothbrush to clean the circuit board. Let it dry for a good 2 hours. Everything works now.

**Nfs021** · 01-18-2023, 05:27 PM

It will also trip the tamper dot. Because when you put it back, the mileage will be less on it than the cars computer. But glad to see a good cleaning sorted it.

**GZilla** · 03-03-2023, 11:46 AM

Originally Posted by seagreen323i

My father had that issue in his 530, turn signal indicators got stuck on. Was a faulty light control module.

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Well, now my turn signal stalk indicators are stuck. In the neutral position it is turned on to the right. I don't know if water caused it. My floor is relatively dry. Do I just by a used LCM and then have it coded? Anyone know of any coding services?

**Jason5driver** · 03-03-2023, 12:40 PM

Originally Posted by GZilla

So I decided to move my E39 from my driveway and onto level ground since there was going to be rain, it had already rained for a couple hours prior. When I started the car it took 5 seconds for the automatic lights to turn on and the night time orange lights in the interior were flickering. I parked the car on the street and went to sleep. Woke up the next morning and noticed that my driver’s side high beam and passenger side indicator is on. I thought it might have been water damage but the passenger side footwell and floor was not wet. I checked my battery voltage and it was 11.6. I unhooked my battery and charged it for a couple of hours until it was fully charged. The same lights are still on.

I’m guessing this is a common issue that many members ask?

It's not the LCM imo ...
It's the low battery voltage ...
Is the battery old / bad ?
How about the alternator ?
Electronics on the E39 will always act crazy when there's low voltage imo .
The car is trying to tell you something ...

**GZilla** · 03-03-2023, 01:07 PM

Originally Posted by Jason5driver

It's not the LCM imo ...
It's the low battery voltage ...
Is the battery old / bad ?
How about the alternator ?
Electronics on the E39 will always act crazy when there's low voltage imo .
The car is trying to tell you something ...

The battery is brand new AGM. I even charged it completely with my battery charger. I am not sure about the alternator if it was changed or not.

**E39 Newbie** · 03-03-2023, 01:14 PM

Originally Posted by GZilla

Well, now my turn signal stalk indicators are stuck. In the neutral position it is turned on to the right. I don't know if water caused it. My floor is relatively dry. Do I just by a used LCM and then have it coded? Anyone know of any coding services?

Get the same part number LCM from a salvage yard. You can DIY the coding if you have PASoft or INPA. I found PASoft to be a lot easier. The LCM keeps the VIN and the mileage. You can swap without coding, but you'll have the tamper dot next to your odometer.

**Jason5driver** · 03-03-2023, 01:48 PM

Originally Posted by GZilla

The battery is brand new AGM. I even charged it completely with my battery charger. I am not sure about the alternator if it was changed or not.

You can have the alternator checked at AutoZone or O'Reilly's for free ...

**GZilla** · 03-07-2023, 09:26 PM

I decided to purchase an LCM 4 from ebay. I took out my old one, cleaned it completely again with alcohol and a toothbrush and checked every port. I even had my indicator stalks replaced with brand new OEM ones. No dice.

E39 Newbie, can I buy the new LCM (mine is LCM 4) from ebay and put it in my E39 to test if it works and then remove and code it? Would it still cause a tamper dot for that brief moment if I don't turn the car over?

Originally Posted by Jason5driver

You can have the alternator checked at AutoZone or O'Reilly's for free ...

Checked it today. Alternator voltage was good.

**Jason5driver** · 03-08-2023, 09:37 AM

What is your battery voltage ?
Still 11.6 ?

**dtw** · 03-08-2023, 10:21 AM

Originally Posted by GZilla

I decided to purchase an LCM 4 from ebay. I took out my old one, cleaned it completely again with alcohol and a toothbrush and checked every port. I even had my indicator stalks replaced with brand new OEM ones. No dice.

E39 Newbie, can I buy the new LCM (mine is LCM 4) from ebay and put it in my E39 to test if it works and then remove and code it? Would it still cause a tamper dot for that brief moment if I don't turn the car over?

Checked it today. Alternator voltage was good.

Yes and Yes. You will immediately have a tamper dot, but it will go away when you a) put your old LCM back in the car or b) you code the eBay LCM.

**E39 Newbie** · 03-08-2023, 12:15 PM

Originally Posted by GZilla

I decided to purchase an LCM 4 from ebay. I took out my old one, cleaned it completely again with alcohol and a toothbrush and checked every port. I even had my indicator stalks replaced with brand new OEM ones. No dice.

E39 Newbie, can I buy the new LCM (mine is LCM 4) from ebay and put it in my E39 to test if it works and then remove and code it? Would it still cause a tamper dot for that brief moment if I don't turn the car over?

Checked it today. Alternator voltage was good.

Yes, it will work but you'll have a tamper dot. No big deal. It goes away after you code the module. You could start it, drive it around, etc., and you won't hurt anything.

**GZilla** · 03-09-2023, 11:22 AM

Originally Posted by Jason5driver

What is your battery voltage ?
Still 11.6 ?

14.6 last time I checked. Granted I didn't turn the car over or sit in it for a while. I have a brand new AGM battery.

**crazy4trains** · 03-09-2023, 12:15 PM

Your battery voltage isn't 14.6. That might be your alternator output voltage.

**GZilla** · 03-09-2023, 01:25 PM

My pulse repair charger showed 14.6 when I had it hooked onto the terminals to charge. Before that it was 12.6. I have an AGM/GEL battery, not a lead/acid one.

**GZilla** · 03-13-2023, 08:14 PM

Put a new LCM 4 I bought from ebay into my car. It fixed the issue. Where can I find the tamper dot everyone mentions? I have it installed and I see no tamper dot anywhere.

**GZilla** · 02-07-2024, 01:43 AM

SoI re-installed my old LCM back in July. We had a major storm and I took the E39 out for a spin and now the malfunction is at it again.Could faulty sunroof drains cause this?

**TiesTorN** · 02-07-2024, 04:30 AM

capacitors on that module are probably toast.

99% of the time "old electronics" actually means "old capacitors". if you replace them (not with cheap chinese craps but with good brands) as preventative maintanence, modules usually last forever.

in this case the damage has already been done. they needed to be replaced before the damage is done. but if I understand right, you are saying it works ok for a while after resetting. so yours may be saved.