S5 LED "Smart Ballast" for cruise control: need to know stop light wires colours
 

Hello!

I changed all my bulbs on my 7 with LED versions! All is working flawlessly except for one thing: the cruise control!!!
The ecu for the cruise control on 80's cars need a small resistance charge otherwise the cruise control wont't engage! Led bulbs are too weak to generate this system charge!

Solutions are
1- Install a single traditional stop light bulb and leave other led bulbs.....so the system charge will be enough and the cruise control will engage....i don't want to do this because it will drain more current and also the light colour is different from other rear bulbs!
2-Install a small resistor before any stop led bulb......again i don't want to do this because it will drain more current and the resistor will generate heat!

3- the "SMART SOLUTION" - Install a "LED SMART BALLAST" that is a device developed for simulating the current charge without wasting current and it's able to fake the cruise control ecu.

The only brand that produce this smart ballast for the cruise control is Bergvillfx and is specifically designed for 80's Porsches but......should work on any 80's car with this system!

I ordered this device and arrived today!

Se the installation manual below:

http://www.bergvillfx.com/files/smartballast.pdf

The istruction manual tells to link this smart ballast both to the "GROUND WIRE" and to the "BRAKE LIGHT WIRE".
On Porsches GROUND WIRE is BROWN COLOUR and BRAKE LIGHT WIRE is Black/RED colour!

On my RX7 FC (European Turbo 2 model) i find the Wires on left and right brake/rear lights: black (that i assume is the ground), then red and green!

Can you tell me what is the right brake light wire between red and green?

I will install this smart ballast in this weekend and tell you if it works even on the 7 as on 80's Porsches

Thank you so much!

brake light wire is Red

Thank you, but......you really sure???

On the FD i read that brake light wire is green and the red wire is simply the lights wire! Is it possibile that between FC and FD wire colours were inverted? It sounds strange...

thank you so much!!!

That's a great document!

I was missing that!

Thank you! :)

@j9fd3s

Sorry if i insist but here they tell the brake light wire connected to the taillight bulb support is the GREEN ONE and the RED ONE is simply the TAILLIGHT "simple" LIGHT

https://www.rx7club.com/2nd-generati...arness-963684/

Can you explain this?

My model is a S5 1991 Turbo 2 Convertibile 91' European model!

Thank you so much! :)

looks like i read it wrong, we are looking at the same thing.

the cruise control is in there too

So the right wire i should connect the ballast is the GREEN ONE? Do you confirm?

Thank you so much! :)

(The FD should be the same: green wire on the tail lights for the brake lights)