Tech Tip: Mercedes key will not turn in ignition

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. 

The technician inspected fuse #78 and found that it was cracked. 

Confirmed Repair: He replaced the fuse and that repaired the problem. 

Information provided by ALLDATA