2001 CLK320 HEAD LIGHT/BRAKE LIGHTS

Only high beam head lights worked
Low beam bulbs burned out
Drivers side headlights went out
Checked drivers side head light bulbs
Wires shorted when checked them
Wires coating brittle and off wires
All signals work front and rear and mirror
When lights are off BRAKE lights work, but not very bright as usual
When turn light switch on, only BRAKE bar works, left and right BRAKE lights appear not to work, or very dim and cannot visually see them on when tail lights are on.
Can keep foot on brakes and turn light switch off and BRAKE lights are still on - bar and both sides
Turn switch back on while foot on brakes and cannot see BRAKE lights
Mercedes dealership do not sell headlight wire harness only full head light replacement($480)
Tried fixing existing wire harness - did not work
Tested in line fuseable link( resistor) - No good - No power
Only place found wire harness only - Partsgeek.com
Bought 2 - one for each side
Installed only drivers side wire harness
Bought new bulbs for high beam and low beam for drivers and passengers side
Did not purchase small standing parking light bulbs
Passenger low and high beams work
Drivers side only low beam
BRAKE lights still performing as described above.
Wire harness leads that run over to low beam have power and (as described above) operate fine.
Power comes through connector plugged into new wire harness connector going through high beam assembly.
High beam does not work
I need help on how to get high beam lights working on drivers side and BRAKE lights operating at full strength with lights off and with lights on.
It appears to me that is, that the BRAKE lights are receiving power with light switch on or off ; however it would seem they are not receiving power when light switch is on because the BRAKE lights are not noticeable at all when taking foot on and off BRAKE pedal.
Can you help me - what's going on?
Btw, I did replace the BRAKE light switch back 4-5 months ago, was not sure if original was still good, just replaced it for good measure.
I'm learning more and more about my CLK320, I've owned it since 2007 and refuse to give money to the dealership for repairs that are not necessary so I choose to learn ,sometimes through a lot of long term pain but work through it. My ClK 320 is in excellent condition and I plan on keeping it for years to come. I'm just handicapped right now because I can't drive it after dusk and need it for our transportation.
Thank you in advance for your assistance.