LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mercedes Benz >> 2017 >> GLS450 >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Electrical Drive System - 166 Chassis >> Basic Knowledge >> Hybrid Drive System Test Conditions, Function - GF08.30-P-2005GRH
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Hybrid Drive System Test Conditions, Function - GF08.30-P-2005GRH

ENGINE 276.821 in MODEL 166 

IMPORTANT The subfunction "hybrid drive system driving conditions, function" is considered and described from the point of view of the hybrid drive system.

We will not go into more detail here about internal signals and function sequences of the internal combustion engine and the A/T.

Function requirements for hybrid drive system test conditions, general 

Hybrid drive system test conditions, general 

Differentiation of the driving conditions during operation is made between internal combustion engine, hybrid driving mode (drive with internal combustion engine and electrical machine (A79/1)) and electric driving mode (sailing mode, maneuvering).

For the driving operation with an internal combustion engine the electrical machine is mostly run as an alternator (alternator mode).

According to the request and charge level of the high-voltage battery (A100g1), in hybrid driving mode, the torque from the electrical machine operates together (supportively) with the torque of the internal combustion engine. The support occurs during moving off and acceleration (boost mode).

In electrical driving mode driving of the vehicle is purely electrical powered by the electrical machine.

The following signals are read in by the ME-SFI [ME] control unit (N3/10) in hybrid mode:

Function sequence for transmission mode and operating mode selection 

IMPORTANT While the handling characteristics can be essentially set by the transmission modes Comfort, Sport, Slippery and Individual "ECO", the operating modes offer the opportunity to have an immediate influence on the use of the electrical energy and therefore on the charge level of the high-voltage battery.

The status of the transmission mode control is read in by the transmission mode control panel (N72/4s1N72/4) and forwarded over the CAN network to the instrument cluster (A1) and the powertrain control unit (N127). When the Individual "ECO" transmission mode is selected, the status of the transmission mode control is forwarded via the CAN network to the audio equipment. The menu for setting the Individual transmission mode appears on the Audio/COMAND display (A40/8). The Individual "ECO" transmission mode is selected using the Audio/COMAND control panel (A40/9). The request from the driver to select the Individual "ECO" transmission mode is sent by the audio equipment via the CAN network to the instrument cluster and the powertrain control unit. The powertrain control unit sets the transmission mode and the IC shows the set transmission mode.

The status of the operating mode selection button (N72/1s16) is read in by the upper control panel control unit (N72/1) and forwarded over the CAN network to the instrument cluster and to the powertrain control unit. The powertrain control unit sets the transmission mode and the IC shows the set transmission mode.

Function sequence for test conditions 

The function sequence is described in the following steps:

Function sequence for drive with the internal combustion engine 

The drive with the internal combustion engine represents the standard driving mode.

Driving occurs in standard driving mode if

Additional function requirements for driving off 

Function sequence for driving off 

The vehicle moves according to the torque request of the driver which is read in by the ME-SFI [ME] control unit, initially purely electrically.

For a respectively high performance request the internal combustion engine is started, rotational speed-synchronized and then coupled to the traction drive. In the case of strong acceleration the electrical machine is supported by the internal combustion engine, in particular for acceleration from low rotational speeds. In the case of driving off from an operating condition with the internal combustion engine, the wet clutch is used as a starting device.

During driving off the request for torque by the driver is read in by the ME-SFI [ME] control unit. The ME-SFI [ME] control unit calculates and distributes the required starting torque to the internal combustion engine and the electrical machine. To do this the ME-SFI [ME] control unit requests an additional motorized torque via the power electronics control unit.

The electrical machine is supplied over the power electronics control unit with energy from the high-voltage battery.

Driving off purely electrically can occur, if

IMPORTANT If the internal combustion engine is off (e.g. automatic engine stop), the oil supply for the automatic transmission is safeguarded via the electrical transmission oil pump (M42).

Function sequence for boost mode 

In boost mode the electrical machine supports the internal combustion engine in order to reach the requested specified torque as quickly as possible or to further amplify the drive torque to amplify the maximum achieved internal combustion engine torque. The period and intensity of the boost mode are hereby dependent on the charge level of the high-voltage battery and the position of the accelerator pedal. Torque synchronization between the internal combustion engine and the electrical machine is realized in boost mode during driving off via appropriate actuation of the wet clutch. To do this the ME-SFI [ME] control unit requests actuation of the wet clutch via the CAN network.

In boost mode in higher vehicle speed ranges the wet clutch is actuated in such a way that just a regulated zero slip situation is set. In order to match the torque request from the driver, the ME-SFI [ME] control unit requests in the same way from the power electronics control unit, as for electrical operation, a torque from the electrical machine which then operates together with the internal combustion engine on the drive.

In order to meet the request for torque from the driver the ME-SFI [ME] control unit makes a request to the power electronics control unit for the maximum available torque from the electrical machine.

The power electronics control unit actuates the electrical machine appropriately based on the signals tolerable discharge voltage/current reported by the ME-SFI [ME] control unit.

To do this the ME-SFI [ME] control unit requests from the power electronics control unit the previously calculated motorized torque from the electrical machine. This is provided with energy from the high-voltage battery over the power electronics control unit and works together with the internal combustion engine on the drive.

Function sequence for electrical operation 

If the transmission mode or the operating mode of electrical drive allows it, the charge level of the high-voltage battery is high enough, the torque request of the driver can be fulfilled purely electrically and no diagnosis or no system error will prevent electrical operation, then this operating condition is adopted. The wet clutch is opened and the internal combustion engine is switched off by the ME-SFI [ME] control unit if certain prerequisites are fulfilled.

At least all of the following prerequisites must be fulfilled and releases awarded:

The function sequence is subdivided into the following transmission modes:

Function sequence for electrical driving mode 

In order to fulfill the torque request from the driver, the ME-SFI [ME] control unit sends a request to the power electronics control unit to provide the required torque directly from the electrical machine in accordance with the load request.

The power electronics control unit actuates the electrical machine accordingly on the basis of the "tolerable discharge voltage" and "tolerable current signals" from the ME-SFI [ME] control unit. To do this the ME-SFI [ME] control unit requests from the power electronics control unit the previously calculated motorized torque from the electrical machine. This is provided with energy from the high-voltage battery over the power electronics control unit and acts on the drive. To do this the high-voltage battery supplies the power electronics control unit with a direct voltage, which is converted into a 3-phase AC voltage.

The ME-SFI [ME] control unit sends the request via the CAN network to the fully integrated transmission control unit for actuation of the wet clutch in order to disconnect the internal combustion engine from the drive. After appropriate feedback the ME-SFI [ME] control unit switches the internal combustion engine off over the opened wet clutch. If during the automatic engine stop a release is retracted or a prerequisite is no longer fulfilled, the internal combustion engine will automatically be started without any defined action on the part of the driver.

Function sequence for creeping 

The creeping that is typical of automatic transmission is simulated electrically via the electrical machine or via the internal combustion engine and slipping of the wet clutch if the brake pedal and the accelerator pedal are not actuated. For creeping in electrical mode the electrical machine is supplied with a low current and operates directly on the drivetrain with acts with the torque that is generated in this way.

For a situation such as a low charge level of the high-voltage battery the creeping is realized over the internal combustion engine and the slip of the wet clutch.

Function sequence for cruising mode 

If the brake pedal and the accelerator pedal are not actuated for a rolling vehicle, the internal combustion engine is disconnected from the drive in Individual "ECO" transmission mode up to a speed > 160 km/h by opening the wet clutch and switched off.

For a slightly actuated accelerator pedal, the electrical machine supports the drive for an adequately high charge level of the high-voltage battery in order to counteract the falling vehicle speed.

In order to do this, the ME-SFI [ME] control unit requests additional motorized torque from the power electronics control unit via the CAN network. This actuates according to the request from the electrical machine.

Additional function requirements for alternator operation 

Function sequence for alternator operation 

During alternator operation the electrical machine, driven by the internal combustion engine, is used as an alternator in order to generate electrical energy.

In order to do this, the rotational energy of the crankshaft is taken up by the rotor of the electrical machine. Rotation of the rotor causes an AC voltage to be induced in the three stator windings. The electrical energy in the form of a 3-phase AC voltage that is generated in this way is limited, monitored and converted into high voltage direct voltage by the power electronics control unit.

The power electronics control unit uses the energy generated to supply the high voltage on-board electrical system, the electrical A/C compressor (A9/5) and the 12 V on-board electrical system and its components.

Additional function requirements for load point shifting 

Function sequence for load point shifting 

The possibility of take up of recuperation energy by the high-voltage battery increases with increasing deviation from the optimal charge level of the high-voltage battery (SOC operating point). This means, if the high-voltage battery is charged or discharged for a low or very high SOC value, increased energy losses are incurred in the form of heat.

In order to reduce this and to keep space open for potentially arising regenerative energy, the high-voltage battery is discharged with the support of the internal combustion engine by the electrical machine for exceeding of a defined SOC value.

In this way the load point of the internal combustion engine is shifted.

That means that the torque of the internal combustion engine is reduced by the ME-SFI [ME] control unit.

The goal is to shift the load points as much as possible within the load point range while maintaining a good efficiency. The load point shift is also used to put additional load on the internal combustion engine.

  Electrical function schematic for vehicle statuses of the hybrid drive system   PE08.30-P-2069-97NAH 
  Overview of system components, hybrid drive system   GF08.30-P-9999GRH 
scientia non olet · About LEMON Manuals