Emergency Override System (EOSys), Basic Function - GF54.21-P-9986A

Model All (4xWD) 

With Code JP2 (Emergency jumper switch) 

Courtesy of MERCEDES-BENZ USA

Overview 

This document contains information on:

• General 
• Function 

General 

The emergency override system (EOSys) can be activated as a preventive measure and in the event of a fault. If activated via a tamper-proof switch (emergency override system button (1)) in the center switch panel, engine running is guaranteed even in the event of severe damage to the drive system, up to mechanical failure.

Function 

• The emergency override system operates with the following component parts:
• Emergency override system control unit
• Drivetrain control unit
• Engine management control unit
• Fuel pump control unit
• Fully integrated transmission control electric controller unit

To achieve full engine output in special hazardous situations, the emergency override system control unit overrides the vehicle's limp-home mode characteristics after activation using the emergency override system button (1).

The emergency override system control unit reads in predefined signals when activated. These are signals that could have a critical impact on engine running (e.g. overheating or lubricant deficiency) and may lead to operating restrictions. If a critical signal is detected by the emergency override system control unit, this signal is edited and forwarded accordingly so that continued driving can be guaranteed even with the risk of potential damage to the drivetrain.