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Third brake light flasher - where to install ?

flip7

Ready to race!
Location
Austin TX
Okay, so I installed THIS third brake light flasher and I built a rectifier circuit similar to the one posted by @flip7.

The flasher works great but I still get a error on the third brake light. Any ideas on what I may have done wrong? Is it possible to install a capacitor backwards?

Thanks!
I do not remember getting an error or having to code anything. The capacitor may not like if installed backwards
What code you are getting? Try resting it with vcds and see if it comes back

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c31561

Go Kart Champion
Location
East Coast, USA
Car(s)
2017 GTI Sport
I do not remember getting an error or having to code anything. The capacitor may not like if installed backwards
What code you are getting? Try resting it with vcds and see if it comes back

I am getting a third brake light error, my mistake for not checking the true code with VCDS. But the flasher works.

I tried an experiment and disconnected the rectifier circuit and the error went away. But the flasher does not work :confused:

So I will make another rectifier. What is the correct direction to install a capacitor? Does the (-) go to the negative side? I am not an electronics guy, but I can follow directions.
 

The Fed

Old Guys Rule
Location
Florida
I looked up USDOT specs. The CHMSL can never flash. Stay away from areas where US Park Rangers patrol. They're federal LEO's. Red Rock Canyon area highways, for example.
 

flip7

Ready to race!
Location
Austin TX
I am getting a third brake light error, my mistake for not checking the true code with VCDS. But the flasher works.

I tried an experiment and disconnected the rectifier circuit and the error went away. But the flasher does not work :confused:

So I will make another rectifier. What is the correct direction to install a capacitor? Does the (-) go to the negative side? I am not an electronics guy, but I can follow directions.
Yes, - sign goes to the ground. Also try a Smaller capacitor. What caoacity is yours and what voltage?

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c31561

Go Kart Champion
Location
East Coast, USA
Car(s)
2017 GTI Sport
Yes, - sign goes to the ground. Also try a Smaller capacitor. What caoacity is yours and what voltage?

Using a 330 micro farad capacitor, 16V. Could not find a 24V as recommended in the DIY.

I made a new rectifier circuit, identical to previous following the correct cap installation. Flasher works like a charm, but still get third brake light error. What size cap would you recommend? Will have to find a multipack to order as components are not readily available where I live.
 

flip7

Ready to race!
Location
Austin TX
The BCM is likely sensing a failure condition.
Assuming you did everything right - i would try reducing the capacitor value. When that cap starts charging, it may pose as a low impedance on the circuit, making the ECU believe there is a short circuit.

If you have 2 x 330uF capacitors available you can try put them in _series_ - so their total capacity becomes 165uF

they need to be connected like this (A)---_||+---_||+---(B)
The outward pins of the resulting capacitor will keep it's polarity sign
Basically A=Negative and B being positive

Do you have access to VCDS?
 

c31561

Go Kart Champion
Location
East Coast, USA
Car(s)
2017 GTI Sport
The BCM is likely sensing a failure condition.
Assuming you did everything right - i would try reducing the capacitor value. When that cap starts charging, it may pose as a low impedance on the circuit, making the ECU believe there is a short circuit.

More to follow after I hook up VCDS.

If you have 2 x 330uF capacitors available you can try put them in _series_ - so their total capacity becomes 165uF they need to be connected like this (A)---_||+---_||+---(B)
The outward pins of the resulting capacitor will keep it's polarity sign
Basically A=Negative and B being positive

Got it, I have a bag of 330uF. I will give that a try as well.

Thanks!
 

takemorepills

Ready to race!
Location
USA
I looked up USDOT specs. The CHMSL can never flash. Stay away from areas where US Park Rangers patrol. They're federal LEO's. Red Rock Canyon area highways, for example.

I guess some people just need to tinker with their car?

I don't like flashing brake light because, duh, the brake light is OFF 50% of the time! And I have noticed the flash rate on these is very low. It is not a stretch to say that someone who just glances up quickly from their smartphone won't really see your CHMSL while it is flashed OFF.
 

flip7

Ready to race!
Location
Austin TX
I guess some people just need to tinker with their car?

I don't like flashing brake light because, duh, the brake light is OFF 50% of the time! And I have noticed the flash rate on these is very low. It is not a stretch to say that someone who just glances up quickly from their smartphone won't really see your CHMSL while it is flashed OFF.

Some blink quite fast or have variable blink rates. Anything which can make the driver behind you more aware - is worth having.

Have you ever wondered when the gal behind you finishes applying her makeup? Or the guy behind you stops texting or shaving?

Most of the times when I brake somehow unexpectedly - I am even manually flashing my hazard lights.

So far - I have not been rear ended even once in 30+ years of driving in US and elsewhere.


Like everything else - to each their own.
 

flip7

Ready to race!
Location
Austin TX
More to follow after I hook up VCDS.

Got it, I have a bag of 330uF. I will give that a try as well.

Thanks!

If this does not make the error go away - there is a chance your flasher module and the entire circuit is not liked by the BCM. Some may present a too low impedance to the BCM output. You may want to try a different flasher module.

You can also try to adjust the channel: ENG116958-ENG116295-Leuchte22BR MA57-Dimmwert AB 22 via VCDS. That will adjust the PWM on that signal.
note your original value though - as always.
 

takemorepills

Ready to race!
Location
USA
Some blink quite fast or have variable blink rates. Anything which can make the driver behind you more aware - is worth having.

Have you ever wondered when the gal behind you finishes applying her makeup? Or the guy behind you stops texting or shaving?

Most of the times when I brake somehow unexpectedly - I am even manually flashing my hazard lights.

So far - I have not been rear ended even once in 30+ years of driving in US and elsewhere.


Like everything else - to each their own.

I've been rear-ended twice, in 1994 by a rust bucket that was hooning and I was stopped waiting for a permissive left turn signal, and 11 years ago by a Ford Ranger pulling an over-sized RV while driving on bald Chinese grease-ball tires on a day when the roads were iced over. Neither incident would have been helped by modified vehicle lighting.

I prefer the people in my "space" to have properly functioning vehicle lighting, and to use it appropriately, i.e. turn signals, which most people seem to not realize is a legal requirement also. The interaction between myself and other drivers is what I use to keep safe.

Another reason I dislike modified vehicle lighting is that I work for a DOT and I have had all of the rules beat over my head many times. Modifying your CHMSL is likely illegal, and to me illegal is illegal.
 

c31561

Go Kart Champion
Location
East Coast, USA
Car(s)
2017 GTI Sport
If this does not make the error go away - there is a chance your flasher module and the entire circuit is not liked by the BCM. Some may present a too low impedance to the BCM output. You may want to try a different flasher module.

You can also try to adjust the channel: ENG116958-ENG116295-Leuchte22BR MA57-Dimmwert AB 22 via VCDS. That will adjust the PWM on that signal.
note your original value though - as always.

Yes, the error does not wish to go away even with a lower capacitance. VCDS shows short or open circuit (guess it can't determine which).

I may have to try another module to see if it makes a difference. Very frustrating.

As for those discussing the flashing brake light, it is a 3-4s flash to draw a drivers attention then goes solid on like a normal third brake light.
 

goes2fast

New member
Location
Aurora, Colorado
My dealer installs the pulse unit on all new cars he sells. I was skeptical at first, but after driving my wife's Jetta a few times, I noticed it made a difference, so I got 2 units, one for my truck, and another for my R that I had to go out of state to find. They are very small units that take no space, and pulse the CHSML 3 times, then goes solid like normal. I am having a hard time identifying the wires I need to tap into on my R, so I ended up here, still not sure which I need?


 
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goes2fast

New member
Location
Aurora, Colorado
I finally found the 2 wires going to the CHSML, and got my Pulse unit installed. It is small enough that it tucked up with the other wires when I put them back. The nice part is this is easily reversible, just unplug, and plug the original wires back together if you don't like it. I have a good relationship with my dealer, so I got my 2 units for free, but I don't think you would have to pay more than $15 or $20 for one, and they do not trigger any warnings on the dash. :cool:


Ah, success!
 
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