Park electronic system Merceds Benz

I am really looking for technical support on the following case and this wirring diagram.
The car data are;
Mercedes Benz C220 CDI -204-C Class model 2010
Manual Normal Gearbox 2.2L-CDI 651.911
ID Number: WDD2042021F505161

I have a Problem with Park electronic System and it does not working. according my snap on scan tool i got the following Code A1291C and it means the power supply for the warning Elements is not enough.
I started checking the power and Ground of the Computer box between pin 18B and 9B is OK.
I have the battery voltage. My Problem is how the voltage should be in normal condition for the LED unit front and back ?
according to this diagram should be A44/3 between pin 8B and 17B , also A44/4 between 7A and 1A.
weither it is AC or DC ?
Also i Need to know Information for the sensor Group front (x26/27) and back ( x35/28), voltage between16B and 7B for Back side Group also 2A and 8A for the fron side Group AC or DC.
Those Information are important for me to compare with my practical results.

I hope that my explaination is clear

Have you checked voltage at the sensor itself? There are intermediate connecters going to sensor. I would check those for green crusties as well as loose pins and ohm test the entire wire run for resistance and possible short to ground on power feed to sensor.

Don't know about Mercedes but on BMW and Land-Rover the sensor ground joins to a common ground wire that runs back to the module the solder on 4 into 1 joint fails/