E53 w/ tekonsha brake controller lights 3rd brake light when manual lever applied

[Warmrain]

I have a 2001 E53 with a newly installed Tekonsha P3 trailer brake controller. Thanks to members on this forum for assisting with this install!

Everything works, no exceptions, everything works fine.

But there is one oddity. When the manual brake lever of the Tekonsha is applied the center brake light of the E53 lights up. No other light gets lit on trailer or car. And yes, the trailer brakes are applied.

I've been through it all, verified again and again that the signal wire is coming from the black and yellow wire of pin 10 of the LCM plug.

Does anyone else have this issue?

Thanks!

Best, ~Cars