LED tail light issue

[David Layton]

My 73 has the LED kit that is sold by Blunttech, but I bought this is 2018, before Blunttech sold these.  I only mention this, so you know which setup I have.  Odd thing is occurring, the right rear brake light is not working.  The left and the center light which is wired to the left brake light are fine as all of the running lights.   Right brake light is wired off of the left, green and red line going across.  Wiring looks correct, the only issue I can think of is one with the little circuit board on the tail lamp.  Any other thoughts? 

[OldRoller]

Swap the dead bulb with another, see if the fault follows. LED's are known to have internal circuit failures. Wouldn't hurt to also check voltage at the right rear housing with brake depressed.

[jimk]

2 hours ago, OldRoller said:

Swap the dead bulb with another, see if the fault follows. LED's are known to have internal circuit failures. Wouldn't hurt to also check voltage at the right rear housing with brake depressed.

His are not bulbs, but led arrays, fitted into the reflector without the use of the bulb socket.  Each array is connected to a small circuit board.  The oe wiring is connected to the circuit board.

[ray_]

You checked to ensure you are getting 12V to the right side brake circuit, right?

 

Cheers,

[John76]

3 hours ago, ray_ said:

ensure you are getting 12V to the right side brake circuit

Dave stated that the left brake light works, so wires appear to be intact all the way from the #12 fuse through the brake light switch to the left brake light. 

 

7 hours ago, David Layton said:

Wiring looks correct

Dave, confirm what @ray_ suggested and check the green/red wire from the L brake light to the R brake light.

If the wire is still intact, you should read +12V with the brakes on. If this is true, then the LED module is most likely defective.

[OldRoller]

10 hours ago, jimk said:

His are not bulbs, but led arrays

Thanks Jim, I stand corrected. I should have realized that led "bulb" replacements weren't even available in 2018... 😳

[ray_]

6 hours ago, John76 said:

Dave stated that the left brake light works, so wires appear to be intact all the way from the #12 fuse through the brake light switch to the left brake light. 

 

Dave, confirm what @ray_ suggested and check the green/red wire from the L brake light to the R brake light.

If the wire is still intact, you should read +12V with the brakes on. If this is true, then the LED module is most likely defective.

Assuming the grounds are in place.

 

😉

[Dudeland]

Led lights are diodes.  Check the polarity of the power.  it won't work in reverse. 

 

Pictures always solve these things. Lots of pictures please, perhaps a short video would help. 

 

Regards

 

[calw]

Without a schematic diagram of the LED array, this is guesswork.  This is NOT an LED headlight discussion, a totally different topic. 

 

The simplest LED light is an LED and a series resistor to current limit it by providing the right voltage.  Most(?) automotive LED's have an array of LED's wired in a combination of series and parallel, along with the LED strip lights that you can get for various applications (think of seeing a cheap strip light with 3 LED's in a row within the strip that are dark- something in that series combo has failed).   Different LED colors operate at different voltages, but it's common to see 3 LED's in series in 12V systems.  Parallel groups of those series wired LED's are used to make larger, brighter arrays.  It can get much more complex from there depending on the light design - Active devices to do the current limiting for an optimum brightness level,  Switching drivers to get to the power consumed/brightness sweet spot (that strobe effect you sometimes notice on the car ahead of you), Sequential gizmos for effects (see Ford Mustang), tail light brains controlled by the car's brain, etc.  Result? Some tail lights that cost more to replace than you spent on that rusty '02 you were going to restore in the 90's... 

 

It's likely your lights are on the simple side, but looking at the photo that Blunt has online, you can see some components other than the LED's  If there is power, and the light is stone dead, it's not an LED failure, it's something in that circuit on the light between the LED array and the incoming power.  Sorry, this doesn't help without knowing the internal design of the tail light.

[visionaut]

2 hours ago, OldRoller said:

 led "bulb" replacements weren't even available in 2018... 😳

Ugh, no... I’ve had my LED bulbs since 2006 at least…likely even older.

[jimk]

I have the same light package.  Attached find the instructions for installation.  Most steps are the mounting instructions for the led array boards.  The interface board is a straight forward install,  disconnect the power wires from the old bulbs and connect to the labeled spade on the interface board, connect the ground wire to the ground spade.

[Gordon]

The LED rear light kit I bought from BluntTech works great in my 74 tii. The only issue, after installing,  the gauge blinker indicator light blinks once turning to the right and goes off. Turning to the left,  no blinks at all from the gauge blinker light.  External blinkers work fine. Guage blinker light worked fine prior to installation of the LED rear light kit. This has me puzzled to say the least...

[Son of Marty]

You need to get a electronic flasher, the led's don't draw enough current for a regular flasher to do it's thing. 

[Twoey]

I had this same issue (74 tii). Top right passanger side led array stopped working. Turns out it was fried! Voltage regulator went bad and it got over volted. 

 

You may not be able to "swap bulbs", however, you can move the arrays around.  Try plugging a different one into that location and see if it works. 

 

If any other one works when it gets plugged in, check the bad board to see if everything looks OK.  If it doesnt work when it's plugged in, bad wiring! 

[David Layton]

The brake lights had been working previously.  I was recently told by a BMW admirer that the brake light was out and we confirmed it.

 

I will check the voltage.  The running lights and turn signals work.  Just the right brake light is not.  This makes me think either the brake wire coming from the left or the circuit board.

Edited April 4 by David Layton