Rear tail /brake light warning

[lewisweller]

Hi guys back again.

My 2006 ctt has the 2008 face lift done by Porsche in Qatar for the first owner. The issue is have is lights on no problem but press the brake and the warning comes up "check rear tail light" or sometimes "check rear break ligts".

Some background info is the 2006 cluster had all incandescent bulbs but this 2008 has a led tail/brake light combo and a side light led. The others are incandescent for reverse, fog and indicator.

Now here come the brain teaser, Porsche charge the customer for two interior courtesy lights which they installed in series or parallel with the lights cluster which is obviously to trick the computer not to throw codes. But why now after 9 years is it not working?

I checked the courtesy bulbs (5w wedge type) and replaced, measure the resistance on all resistors on the pc and all looks correct and identical both sides.

To recap the tail lights do work but only. If you brake it stops working and throws the code. The brake lights will continue to illuminate but when off the tail lights are not then on as it should be.

Strange and had Piwis and durametric scan to no joy. The fault skips from side to side on the diagnostics.