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Discussion Starter · #1 ·
Hi Alfa Owners!,

I have a very strange behaviour on my 2015 Giulietta 1.4T 170 BHP 940 model.
Since a while, the 3rd break light (the one on the spoiler) never turns off, even when I shut down the car. Instead, it dims a lot, but keep on. When I break, it turns to maximum and then dim when I release the pedal. Because it is led and dims I am not having any problem with the battery.
I was able to buy an used one and change it, and the behaviour is the same.
Any Ideas?.

Thanks!!!!
 

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for starters i'd take the light out and check the connection for corrosion.
 

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Discussion Starter · #3 ·
for starters i'd take the light out and check the connection for corrosion.
Thanks!, I tried 2 different lights (the original and a spare part I bought), and the same with both. Do you think that can be something with the cable?.
 

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Check the wiring harness through the rubber gators from car to tailgate for broken insulation and shorting across circuits.
Here’s a wiring diagram for brake lights.

Also colour code table for wires.

if wiring checks out on tailgate I would have a check of the BCM output,you might have to split the green/black cable from plug F pin 48 to see what side the cable is getting slight power from.
 

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Discussion Starter · #5 ·
Check the wiring harness through the rubber gators from car to tailgate for broken insulation and shorting across circuits.
Here’s a wiring diagram for brake lights.

Also colour code table for wires.

if wiring checks out on tailgate I would have a check of the BCM output,you might have to split the green/black cable from plug F pin 48 to see what side the cable is getting slight power from.
Thanks Johnny!!!, this is pure gold!!!!. I will review today and write an update.
 

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I would say you have an issue with the Driver Chip for the brake lights in the Body Computer.
Very happy to be wrong, fingers crossed.
 
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fit a resistor across the third brake light if you can't find a solution. 600 to 1000 ohm should be perfect, half watt. It will consume the current that's lighting the leds dimly, but won't affect normal operation.
 

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Discussion Starter · #8 ·
fit a resistor across the third brake light if you can't find a solution. 600 to 1000 ohm should be perfect, half watt. It will consume the current that's lighting the leds dimly, but won't affect normal operation.
Thanks for the advise, I will run all the diagnostic this afternoon and if I fail to find the source, this sound as a great solution!
 
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