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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Cosmetic and Lighting Modifications (exterior/interior) > BMW E90 rear tail lights not working



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      01-09-2020, 02:21 PM   #1
Rossyg1996
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BMW E90 rear tail lights not working

any ideas on whatís wrong here.. right side is not working as you can see from picture, Iíve changed the bulbs, build holders and even test on a multimeter power is going to the bulbs. Any help appreciated
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      01-09-2020, 03:36 PM   #2
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i think i maybe wrong on this one because its only the inside light, but i recently had one of my LED taillights stop working. It was the actual tail light but after replacing with a new taillight it still didn't work. did some reading and found out the LCM will stop supplying power to taillight after it notices it has been out after your turn the car on and off about 50 times.( every time you turn your car on and the light is not working it sets a counts every time, after it counts 50 it permanently turns off power) the only way to get it working again was to reset the LCM through coding. I found an android app called Deep OBD for BMW that i was able to reset the counter. It was hard and took me many hours to figure it out. If I were you I'd look into reseting the LCM counter just in case.
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      01-09-2020, 04:04 PM   #3
Rossyg1996
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Originally Posted by DM_e92 View Post
i think i maybe wrong on this one because its only the inside light, but i recently had one of my LED taillights stop working. It was the actual tail light but after replacing with a new taillight it still didn't work. did some reading and found out the LCM will stop supplying power to taillight after it notices it has been out after your turn the car on and off about 50 times.( every time you turn your car on and the light is not working it sets a counts every time, after it counts 50 it permanently turns off power) the only way to get it working again was to reset the LCM through coding. I found an android app called Deep OBD for BMW that i was able to reset the counter. It was hard and took me many hours to figure it out. If I were you I'd look into reseting the LCM counter just in case.
do you know if there's any fuses for the rear lights. Just checked and can't seem to find one, checked all fuses that resembled lights from the fuse card and everything's all good.
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      01-09-2020, 11:40 PM   #4
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Thereís no fuses. Itís all in your FRM module.
Weird youíre getting power. Usually, the frm module stops sending power to the bad side and wonít give you a reading.
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      01-10-2020, 03:01 AM   #5
Rossyg1996
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There’s no fuses. It’s all in your FRM module.
Weird you’re getting power. Usually, the frm module stops sending power to the bad side and won’t give you a reading.
Could it be a bad earth ? Or would I not get power at all if that was the case ?
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      01-10-2020, 03:50 AM   #6
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Could it be a bad earth ? Or would I not get power at all if that was the case ?
No, you would not get power if the earth ground wire was bad.
You said you already changed the bulb holder?
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      01-10-2020, 04:05 AM   #7
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Could it be a bad earth ? Or would I not get power at all if that was the case ?
No, you would not get power if the earth ground wire was bad.
You said you already changed the bulb holder?
Changed Bulbs, Bulb Holder and have 11/12volts going to the connector .. strange
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      01-10-2020, 04:51 AM   #8
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Where are you grounding the Negative side of your multi meter?
If youíre grounding it on the car, then yes, a bad earth wire could cause the issue if the bulb housing is not getting any ground.
Find the earth wire on the plug and check resistance between the earth on the plug and a ground on the car.
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      01-10-2020, 04:57 AM   #9
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I’m assuming you are using a multi meter.
Where are you grounding the Negative side of your multi meter?
Just on the inside of the boot, un-lacquered bit of metal
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      01-10-2020, 05:31 AM   #10
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Ok, so the meter completes the circuit from the plug power wire to the body so you get 12v when you measure.
You would need to find the ground wire on the plug and check the voltage from both wires on the plug.
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      01-10-2020, 10:37 AM   #11
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Quote:
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Ok, so the meter completes the circuit from the plug power wire to the body so you get 12v when you measure.
You would need to find the ground wire on the plug and check the voltage from both wires on the plug.
Just done that there and got a reading of 6volts
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      01-10-2020, 10:42 AM   #12
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Quote:
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Quote:
Originally Posted by Serf27 View Post
Ok, so the meter completes the circuit from the plug power wire to the body so you get 12v when you measure.
You would need to find the ground wire on the plug and check the voltage from both wires on the plug.
Just done that there and got a reading of 6volts
You have a bad ground. Check for broken wires where the wiring goes from the trunk lid into the body.
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      01-10-2020, 10:55 AM   #13
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Quote:
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Quote:
Originally Posted by Rossyg1996 View Post
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Originally Posted by Serf27 View Post
Ok, so the meter completes the circuit from the plug power wire to the body so you get 12v when you measure.
You would need to find the ground wire on the plug and check the voltage from both wires on the plug.
Just done that there and got a reading of 6volts
You have a bad ground. Check for broken wires where the wiring goes from the trunk lid into the body.
Just tired again and it's back up to 12volts. Driving me insane now lol
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      01-10-2020, 03:40 PM   #14
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The ground wire is probably broken somewhere and barely making contact. Thatís why you got 6v then 12v.
I would check the wires right where they exit the trunk and enter the car.

Did you check if the bulb worked when you measured 12v?
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      01-10-2020, 03:45 PM   #15
Rossyg1996
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Quote:
Originally Posted by Serf27 View Post
The ground wire is probably broken somewhere and barely making contact. That’s why you got 6v then 12v.
I would check the wires right where they exit the trunk and enter the car.

Did you check if the bulb worked when you measured 12v?
Lights didn't work on either 6v or 12volts, the bulb holder and lights work when I switch it over to the other side. So has to be down to wires or something else stopping it
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      01-10-2020, 05:04 PM   #16
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Quote:
Originally Posted by Rossyg1996 View Post
Quote:
Originally Posted by Serf27 View Post
The ground wire is probably broken somewhere and barely making contact. That's why you got 6v then 12v.
I would check the wires right where they exit the trunk and enter the car.

Did you check if the bulb worked when you measured 12v?
Lights didn't work on either 6v or 12volts, the bulb holder and lights work when I switch it over to the other side. So has to be down to wires or something else stopping it
Could be a nearly broken wire. Enough to show voltage, but not enough to carry any current. If you measure the voltage drop on the wiring, you would probably see nearly 12V drop in the wire when trying to operate a light.
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      01-12-2020, 12:17 PM   #17
Rossyg1996
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Problem solved, broken wire.
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