This post show you the experience on how to repair BMW PDC system trouble.More repair cases about BMW,please check here:BMW Trouble Repair
When hang reverse gear,PDC switch light flashing and the console show the PDC system error as below.
Connect ICOM and run with ISTA-D get the trouble code 9E3B Power Supply sensor park assistense.
According to the diagram,all parking sensors supply from one power supply together.If one of the parking sensor short circuit,the voltage will be reduced to 2.7V.Mechanic test and replace the broken sensor with new one,but the voltage still show 2.7V,so it seem the PDC module was damaged.
Disassemble the PDC module,and take out the PCB to check.Mechanic found the 5WC power triode was damaged.
After solder a new working power triode to PDC module PDC,the trouble was solved!
Install all parts back on car,tested PDC system work well.