Tech Tips (by ALLDATA): Mercedes key won’t turn in ignition

TECH TIPS (courtesy of ALLDATA)

Vehicle: 2004 Mercedes Benz S 430 (220.170), V8-4.3L (113.941), Automatic Transmission

Mileage: 199,776

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.