when appling the brakes my 3rd brake light flashes like a strobe light,can hook it to my standard brake light and it works But,looking for what voltage a 3rd led brakelight uses on a mercedes c220 cdi 2003 model estate in case it has to be reduced voltage
The rear lights are controlled by the rear SAM module. It is located under the boot/trunk carpet or behind the side trim.
It will supply 12V to the center stop light, but if you disconnect it and feed the light from one of the side brake lights a error warning may appear on the dashboard, either because it will detect no light in the center light or the increased current on the side light you have connected it to.
However I'm not sure if your exact model has bulb fault detection so I would recommend using temporary connections (just twist and tape) and keep pressing the brakes or hold the pedal down for a while and see if a error appears, if it doesn't then you can make the connection permanent. If a error does appear then send the SAM unit off for repair.