Tech Tips (by ALLDATA): Mercedes key won’t turn in ignition
TECH TIPS (courtesy of ALLDATA)
Problem: The vehicle was towed in because the key would not turn on the Electronic Ignition Switch (EIS).
Details: The technician attempted to communicate with the EIS, it was not possible. At that point, he called Tech-Assist.
The Tech-Assist consultant studied the wiring diagram and found a possible problem. In the Power Distribution diagram, fuse #78 in the Cockpit Fuse Box powers the EIS itself (see the wiring diagram below).
The technician inspected fuse #78 and found that it was cracked.
Confirmed Repair: He replaced the fuse and that repaired the problem.