Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
My name is ***** ***** I am a fully qualified vehicle technician with over thirty years in trade hopefully I can help.
As the wiper motor has been replaced but no power is now reaching it, the two most likely problems are either the loom between the rear door and the body or the boot closure module.
The short loom between the body and the hatch may have a fractured wire, this is quite common and the wire should be checked for any damage.
The boot closure module controls the power to the rear wiper motor and if this has failed then it would explain why the wiper is not operating, the module is located to the n/s rear of the load area.
It may be necessary to check the system using the Mercedes STAR diagnostic system, this would pip point the problem.
I hope this answers your question but do please feel free to ask any further details by replying to this thread.