P0121 Mercedes-Benz -

Question

What is the voltage and the wire colors in out also what pins do I have to check on ECU also the wire colors and can you back probe them without any problems or damage arising from the ECU or damage to it also need voltage? I don't have a repair Manuel or good Scan tool can you recommend one. Thanks for the help I am a BMW Master tech but the BMW tester won't help me with a Benz 430 clk 2002 has 50000 miles on it please email me at doug.hudson [email protected]
Thanks again Doug