Skene Tail LEDs- SOLVED

[Stuarto72]

On Dec 22, 2021, stuart.ostroff@verizon.net wrote:

I just installed a P3-TS kit on my Moto Guzzi V85TT.  I have installed 4 or 5 kits on previous bikes, and have a set also on my Triumph Tiger.

I followed the wiring instructions carefully and spliced into the harness which goes to the tail lights. 

I used the  yellow / green bike lead for the brake trigger, and connected the white controller wire to that.  I chose that wire for brake based on the bike schematic - although the brake connection is a bit confusing.  The turn signals work fine, as they should, but the BRAKE OPERATES BACKWARDS.  When I actuate the brake the bike's tail light glows bright but the LED's do not brighten.  When I release the brake the LEDs flash 4 times, then goes steady bright. I tried one other bike wire (Yel/Grey) but then the LEDs do nothing.   
Can this function be corrected by programming? 

REPLY FROM SKENE:   

Hello Stuart,

Thank you for contacting us about the problem installing the P3-TS on your Moto Guzzi V85TT.

It sounds like the lights come with the ignition and respond as expected to the left and right turn signals. 

Do the lights flash 4 times and go solid at 100% when the bike first starts up?  That would imply that the bike’s yellow/green wire receives 12 volts when the ignition is turned on.

On almost all motorcycles the brake light is activated by applying 12 volts to the brake.  On a few the brake is turned on by grounding the brake wire.

You can test that wire with a voltmeter and determine the voltage  with and without the brakes applied.  That would confirm the hypothesis above.

If that is the case on your bike you can add a small relay to the brake wire to adjust for that difference.

Please try testing the voltage and send us the results along with the wiring diagram for your bike.  We’ll take a look and provide some specifics on what to adjust.

Regards,   Bill              bill@skenedesign.com

MY REPLY:

Hi Bill:

I just used a meter and checked the voltage present between ground and the Yellow/Green wire going to the brake light (I think).  It reads 0.8V with no brake applied, and zero when the brake is applied.  When I turn the key ON the LEDs give 4 bright flashes then stays on.  When I apply the brakes there is no change on the LEDs, but when I release the brake it gives 4 bright flashes, then steady. There are no other unused wires going to the tail light. 

As I study the wiring diagram (which I reprinted 24 X 36 so I could read it)  I notice that the brake switches are both double throw and have 3 wires. 
I wonder if I should be connecting the WHITE brake wire from the controller to the rear brake lead? 

Stuart

[Kiwi_Roy]

Its obvious that the V85 stop light has some special function, the stop switch wiring disappear into the dash but the output to the Stop Light comes from the ECU
https://www.thisoldtractor.com/guzzi007/schematics/2019_V85_TT.gif
I wonder what special functions of the bike logic you are disabling.
As you say the switches are form C, i'm not sure why, interested to see how it works out for you.

[egschade]

This info is from Harry in our NJ group. Basically you need to install a relay across the tail light / brake light lines and use it to trigger the aux lights:

Did you ever hear the term "Opened a can of worms" well you just opened a shipping container full of worms.
The Tail Light is really a matrix of LEDs with a control point in the middle that controls half the LEDs.
The blue wire(B)  is ground .  G/V (Yellow Green) is taillight 12V.  G (yellow) is brake light {think of it as control wire 8V or nothing}.   These are colors from the wiring side of the plug.

Key on. 12v + ground across the LEDS tries to turn them all on. BUT the control lead (G) has 8V so it back biases half the LEDs and they just glow.    Hit the brakes (G) goes to nothing and all the LEDs come on.  Not 100% sure I'm remembering the G lead right on the voltages I didn't write it down.

Here's a link to schematic:
https://www.thisoldtractor.com/mg_manuals/wiring_diagram_v85-tt_en.pdf

You have to wire in a relay.  I used a regular 30A relay like for driving lights just because I always have a few around.  The difference in voltage between the G and VG is enough to activate the relay under breaking.  A smaller mini relay would have been easier to stick somewhere.  I also used Posi-locks to connect to the old wires, because they can be removed later and you don't have to cut into the wiring harness.  Down side is you have to stuff them some where.

I called Skene Lights when I started this and they were little help.  Two weeks after I figured it out they sent me this diagram.  it might not be exactly what your doing but if you look at it long enough it might help.

Basically it's just taking that brake 'control lead' and turning it into a 12v brake input into your aux lights.  So you end up with 12v Tail Light/ 12v Brake light and ground.
.

[Stuarto72]

Thanks for your prompt reply.  I am using the yellow (tail light 12V+) to trigger my Aux Power relay.  I have the schematic you refer to.  But not very  clear on the wiring / function of the tail light. 

Sounds like you are suggesting a 12V relay with the coil between Yellow and Yellow / Green.  When brakes applied the Y/G goes to -0- and the relay turns on.   And the contacts of the relay would provide BRAKE trigger to the Skene controller?   ~~~~  Running out of space under the seat  ~~~

Stuart

[twowheeladdict]

Love Skenedesign lights.  Hope you get them to work for you.  I have them on my V7III and KLX300SM.

[j.davis]

Tried them on my V85, doesn't work as the tail light is almost a canbus system with varying voltages.
A friend on the ADVBIKJE forum made a circuit to make an aux flashing light, but is a very complex workaround.

[Stuarto72]

Thanks to Egschade and Harry from NJ I was able to add a simple SPST relay and trigger the SKENE brake lights.  Diagram to follow. 

Stuart

[twowheeladdict]

 

[Stuarto72]

I tried to attac a PDF of the CAD wiring drawing but pdf no permitted. 

So here is a photo of the drawing.  I hope this works! 

Stuart

[mojohand]

Nicely done!

[egschade]

I tried to attac a PDF of the CAD wiring drawing but pdf no permitted. 

So here is a photo of the drawing.  I hope this works! 

Stuart

Well done sir! Glad the info was helpful.

[Wayne Orwig]

Curiosity got the better of me. That connector on the taillight is a royal pain to get to.

This is nothing like the Norge and Breva taillight issue. This is actually pretty simple.
The 12V on the yellow wire powers the taillight to ground (the blue wire).
That is it for the taillight LEDs.

The brake light LEDs are tied to the yellow 12 volt wire. To light the brake light LEDs, you ground it, through the yellow/green wire.
Simple, but backward from a normal brake light of course.
The head scratching comes in because the slight current through the meter (or maybe a bleed resistor in the electronics), is biasing the LEDs and dropping about 4 volts. As in 12.5 minus about 4 gives you about 8.5 when you measure it on the yellow/green wire. In fact, that may be a smart LED test. As in, if the LED fails, the brake light voltage gets pulled to zero and the brake light is bad. The electronics senses that. Maybe.

Too bad Skene does not have a quick way to connect to a reversed signal like that.

So, simply adding a relay coil from yellow to yellow/green fixes it. With that coil in place, you measure close to 12V on the yellow, and close to 12V on the yellow/green, until you apply the brake. Since the low coil impedance will pull the yellow/green, from 8 something.

One thing to keep in mind, since the driver involves the electronics, when the relay coil collapses, you will get a voltage kick. No way to know how well it is protected from that. I have to believe it is protected very well, and not a problem, going to the outside world like that.