Emergency driving mode/emergency engine stop EDC function

W54.30-0010-01

Display without gear indication
(models without EPS transmission)

EPS-Display with gear indication
(models with EPS transmission)

W54.30-0009-01

If a fault occurs at the FMR or the EDC system when driving or when the engine is running (EDC warning light comes on), the type of fault (readout in FDS display) determines whether restricted driving is still possible (emergency driving mode), or whether the emergency engine stop is activated.

The EDC system monitors itself and activates the engine emergency stop, if necessary.

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 If this fault activates one or several fault codes, the readout appears immediately in the FDS display. If the fault exists only for a short time, the fault code disappears in the FDS display. The relevant fault code is stored in the control unit, however, for subsequent analysis.

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Minor fault  Vehicle can still be driven.

Moderate fault  Vehicle can still be driven to the nearest MB Workshop.

Major fault  Before driving on, call a MB Workshop or MB Brakedown Service. An emergency engine stop is activated.

Emergency driving mode

Minor faults at EDC components result in a reduction in power or in maximum engine speed. In the case of moderate faults at EDC components, the system switches over to suitable substitute functions, e.g.

- Failure or open circuit from/to foot throttle actuator:

Kickdown switch performs the engine speed control function.

- EDC speed sensor or needle motion sensor faulty:

Start of the injection control is carried out with the aid of the on/off ratio of the square-wave voltage at the control sleeve solenoid of the injection pump. The characteristic values required for this are stored in a map in the control unit.

Emergency engine stop

The emergency engine stop in the event of a major fault functions as follows:

- Actuation of engine brake to reduce engine speed.

- Actuation of constant throttle to interrupt the combustion process.

- Actuation of the electric shutoff device (ELAB) for interrupting the fuel supply.

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The engine can no longer be started if any of the following faults exist:

- EDC control unit faulty (quantity or start of injection output stage).

- Control sleeve injection pump faulty (fuel metering actuator or fuel rack position sensor).

- FMR or EDC speed sensor faulty.