vincentp

I'm sorry to necropost this but I'd rather revive than create a new thread. I think that brake light issue narrowed down what I've experienced with my (retrofitted) cruise control on my 1998 996 (servo CC unit). It works and I can set the speed, release on manual switching, or clutch / brake switch.
However, I went for a road trip yesterday and noticed the loss of the CC while on the highway while I was expecting to be able to use it (which is the reason why I spent the massive amount of time to retrofit the CC unit).
After a few stops on rest areas and a few tries, I noticed that it was linked to the spoiler being extended, even if I wasn't driving (I have also a in-dash spoiler control + indicator). When it goes extended, as soon as it seems to be seen as "in extended position", the green light of the CC (instrument cluster) vanishes and will not come back even after retracting the spoiler (I have to turn the key off then on again).
My car also got modded (previous owner) by TechArt and has tail lights with leds (and proper resistors). I don't know if the second (spoiler) 3rd-stop-light has been converted but would that spoiler extended switch (humschalter HMS, drive spoiler block, wiring diagram 97 page 65 of the wiring PDF) be responsible of this ?
Missing resistor in the spoiler stop switch ? Just fetching advice before I take this apart.

the weird thing is that the problem occurs even without pressing on the brakes, but only when switching the power source to the 3rd brake light (it seems) in the spoiler system. Would the DME (or something else) would notice an issue in the spoiler stop light and disable the CC unit ? how would it do that ? via the instrument cluster pin (diagnostic pin) ?

thanks

vincentp

A follow up to my own post in the case it helps others : Looking at the schematic / electrical wiring diagram of the car, the two third brake lights are linked and are also monitored by the car control unit. If a failure is found in the strop / brake lights, you aren't allowed to use the cruise control, which makes sense.
It ended that :
- my new LED replacement of the spoiler brake light didn't have a load and while the circuit between the 2 lights (car and spoiler) was ok, the spoiler one was considered as dead. I managed to retrofit a power resistor, just like it's done on most LED lights conversion.

Leedlast

On my '03 996, I simply replaced each of the brake lights, tail lights, backup lights and the seven bulbs in the center high mount light fixture with individual bulbs that I bought either from www.superbrightleds.com or temu. I also replaced the flasher and had no problems with any hyper flashing or anything else. Plug and play. I'm not sure this helps you, but I'm just pointing out that even without the electronic flasher, it all worked without adding resistors.