LEMON Manuals: Even more car manuals for everyone
Home >> Mercedes Benz >> 2021 >> E53 AMG 2D Convertible >> Repair and Diagnosis >> Body & Frame >> Sun Roof/T-Top/Convertible Top >> Sliding Roof, Soft Top, Top Attachments - 238 Chassis >> Basic Knowledge >> Electric Panoramic Sliding Sunroof, Function - GF77.20-P-0003FH

Electric Panoramic Sliding Sunroof, Function - GF77.20-P-0003FH

Model 238 

up to model year 2021 

with code 413 (Panoramic sliding sunroof/glass roof) 

G15467042Courtesy of MERCEDES-BENZ USA

Function requirements, general 

Electric panoramic sliding sunroof, general 

The front section of the panoramic sliding sunroof can be opened and closed again in the tilt or slide position. An extended roller sun blind is retracted before the panoramic sliding sunroof is opened. The panoramic sliding sunroof is operated via the roof system switch at the overhead control panel control unit.

Overheating protection: 

The panoramic sliding sunroof motor and the roller sun blind motor are protected against overheating by a software thermal protection in the panoramic sliding sunroof control unit. The temperature in the panoramic sliding sunroof motor and roller sun blind motor is calculated taking into account the voltage, current and actuation duration as well as the outside temperature.

The front SAM control unit directly reads in the signal of the outside temperature sensor, calculates the outside temperature and sends it to the panoramic sliding sunroof control unit via interior CAN.

Detection of switch signals: 

The actuation of the roof system switch is clearly detected after 40 ± 10 ms. The max. actuation duration is 20 s. A defective roof system switch is interpreted after 60 s. A new actuation (triggered via the roof system switch) can only be performed again after detecting that the roof system switch is in the rest position.

IMPORTANT There are comfort functions for opening and closing the panoramic sliding sunroof that facilitate a central opening and closing together with the side windows from one control point.

IMPORTANTRoof rack 

If a roof rack is installed on the vehicle, the panoramic sliding sunroof should not be opened. A roof rack released by Mercedes-Benz has an end stop. This prevents damage where the panoramic sliding sunroof is opened. Once the panoramic sliding sunroof comes into contact with this end stop, the panoramic sliding sunroof control unit detects an obstacle due to the changed power consumption of the panoramic sliding sunroof motor. Actuation is interrupted and reversing is started up to the tilt position.

The electric sliding roof panoramic function comprises the following partial functions:

Position detection 

The position of the panoramic sliding sunroof and that of the roller sun blind are determined by the panoramic sliding sunroof control unit by evaluating the signals of the following sensors:

The Hall sensors are located on the shafts of the roller sun blind motor and panoramic sliding sunroof motor, offset in each case by 90°. The position of the panoramic sliding sunroof and roller sun blind are detected by counting the Hall sensor pulses. The zero position (roller sun blind and/or panoramic sliding sunroof fully closed) is set via normalization.

IMPORTANT If the Hall sensors fail, the roller sun blind can only be actuated incrementally at intervals of, in each case, 0.3 s. The panoramic sliding roof can only be closed with the hand crank.

Additional function requirement for "normalize panoramic sliding sunroof" 

Normalize panoramic sliding roof 

Normalization is the basis for the assignment of the current position to the position of the roller sun blind and/or the panoramic sliding sunroof recognized by the panoramic sliding sunroof control unit. To do so, the panoramic sliding sunroof and the roller sun blind must be closed completely.

Manually close the panoramic sliding sunroof and roller sun blind via the roof system switch until the mechanical end position is reached. The overhead control panel control unit transmits the status of the roof system switch via the interior CAN to the overhead control panel control unit.

Then reactuate roof system switch for min. 1 s. By evaluating the signals of the Hall sensors, the panoramic sliding sunroof control unit recognizes the blockage and sets the corresponding location counter to zero.

Denormalization is performed under the following conditions:

IMPORTANT The position of the panoramic sliding sunroof and the roller sun blind cannot be determined in the denormalized state. The function is then limited to manual closing or opening. Actuation is only possible in intervals of 0.5 s in each case.

Blockage detection 

An obstruction is detected, if no Hall sensor signals are detected during an adjustment for approx. 160 ms.

If an obstruction is detected in the closing direction, the roller sun blind motor and panoramic sliding sunroof motor are stopped and then actuated in the opposite direction. If an obstruction is detected in the opening direction, the roller sun blind motor and panoramic sliding sunroof motor are stopped and not further actuated.

Additional function requirements for automatic reversing function 

Automatic reserving function 

If the closing of the panoramic sliding sunroof or roller sun blind is obstructed or restricted, the panoramic sliding sunroof or roller sun blind automatically opens again.

The automatic reversing function is based on the comparison of the current rotational speed of the roller sun blind motor and/or panoramic sliding sunroof motor with that determined during a teach-in run or due to an adaptation.

If a specific limit value is exceeded during closing during this comparison, the panoramic sliding sunroof control unit evaluates this as an obstruction.

During automatic opening, the automatic reversing function is active in a limited range (protection against risk of pinching from glass cover rear edge/roof rack).

IMPORTANT During a teach-in run, the roller sun blind and the panoramic sliding sunroof are moved in normalized status through all closing processes. The panoramic sliding sunroof control module adapts to changes in the rpm resulting from increased sluggishness (e.g. dirt in the mechanical system).

Where an obstacle is detected during opening, the roller sun blind motor and panoramic sliding sunroof motor are solely stopped. Where an obstacle is detected during closing, the roller sun blind motor and panoramic sliding sunroof motor are initially stopped and then reversed (in the opposite direction).

Reversing of 145 mm is performed during automatic closing.

Reversing of 70 mm is performed with the rain closing function.

Reversing of 20 mm is performed during manual closing.

Special case closing panoramic sliding sunroof manually: 

A higher force expenditure is permitted where the roof system switch is actuated in the close direction within 2 s of reversing. The next closing attempt deactivates the automatic reversing function.

additional function requirements for opening/closing of roller sun blinds 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 to the panoramic sliding sunroof control unit via the interior CAN. The front door control units transmits the status of the front doors (open or closed) to the panoramic sliding sunroof control unit via interior CAN.

IMPORTANT When a front door is opened or closed during the run-on time, this triggers a restart of the run-on time.

Open/close roller sun blind 

The roller sun blind is opened or closed for the actuation duration via the actuation of the roof system switch to the first detent. The roller sun blind is moved to the last saved position or fully opened or closed via the actuation of the roof system switch beyond the first detent. The automatic operation is canceled by actuating the roof system switch again.

The overhead control panel control unit directly reads in the roof system switch status and transmits this via the interior CAN to the panoramic sliding sunroof control unit. The panoramic sliding sunroof control unit accordingly actuates the roller sun blind motor. The automatic reversing function is active during closing.

Additional function requirements for opening/closing panoramic sliding sunroof 

IMPORTANT The electronic ignition lock control unit sends the status of circuit 15 to the panoramic sliding sunroof control unit via the interior CAN.

IMPORTANT When a front door is opened or closed during the run-on time, this triggers a restart of the run-on time. The front door control units transmits the status of the front doors (open or closed) to the panoramic sliding sunroof control unit via interior CAN.

Open/close panoramic sliding roof 

The panoramic sliding roof function comprises the following partial functions:

Open/close panoramic sliding sunroof in slide position 

The panoramic sliding sunroof is opened or closed for the actuation duration via the actuation of the roof system switch to the first detent. The panoramic sliding sunroof is moved to the last saved position or fully opened or closed via the actuation of the roof system switch beyond the first detent. The automatic operation is canceled by actuating the panoramic sliding sunroof switch again.

The overhead control panel control unit directly reads in the roof system switch status and transmits this via the interior CAN to the panoramic sliding sunroof control unit. The panoramic sliding roof control unit actuates the panoramic sliding roof motor. The automatic reversing function is active during closing. During automatic opening, the automatic reversing function is active in a limited range (protection against risk of pinching from glass cover rear edge/roof rack).

Additional function requirements for raising/lowering panoramic sliding sunroof in tilt position 

Raise/lower panoramic sliding sunroof in tilt position 

The panoramic sliding sunroof is raised in the tilt position or lowered out of this for the actuation duration via the actuation of the roof system switch to the first detent. An automatic operation starts where the roof system switch is actuated beyond the first detent. The panoramic sliding sunroof is raised to the last saved position or fully raised in the tilt position or lowered from this. The automatic operation is canceled by actuating the panoramic sliding sunroof switch again.

The overhead control panel control unit directly reads in the roof system switch status and transmits this via the interior CAN to the panoramic sliding sunroof control unit. The panoramic sliding roof control unit actuates the panoramic sliding roof motor. The automatic reversing function is active during closing.

Rain closing (except code 494 (USA version)) 

The automatic rain closing function prevents rainwater from entering into the vehicle interior. A panoramic sliding sunroof opened in the slide position is fully closed and raised in the tilt position. A panoramic sliding sunroof fully opened in the tilt position is lowered in the case of heavy rain.

Rain closing comprises the following partial functions:

Additional function requirements for rain closing when vehicle is parked 

IMPORTANT The status of circuit 15 and the status of the central locking are sent by the electronic ignition lock control unit via the interior CAN to the panoramic sliding sunroof control unit.

Rain closing function where vehicle is parked 

When it starts to rain, the panoramic sliding sunroof opened in the slide position is fully closed and raised in the tilt position. "Starting to rain" is defined via the wetness of the windshield.

Moistening the windshield is recognized by the rain/light sensor with additional functions. The rain/light sensor with additional functions reads in the signals from the rain sensor directly and evaluates them. The rain and light sensor with additional functions then transmits the request for the "rain closing function" to the panoramic sliding sunroof control unit via the rain and light sensor LIN, front SAM control unit and interior CAN. The panoramic sliding sunroof control unit actuates the panoramic sliding sunroof motor. The panoramic sliding sunroof is adjusted to the tilt position. Monitoring is then no longer performed.

IMPORTANT Model 238

up to model year 2021

with code 413 (Panoramic sliding sunroof/glass roof)

with code 882 (Interior protection and tow-away protection)

During rain closing, an alarm actuation is suppressed by the interior protection to prevent an unintentional actuation of the anti-theft alarm system (ATA).

The rain closing function is also triggered under the following conditions:

Additional function requirements for dynamic rain closing function (during vehicle operation) 

Dynamic rain closing function (during vehicle operation) 

With the dynamic rain closing function, the raised panoramic sliding sunroof automatically lowers out of the tilt position during vehicle operation in the case of heavy rain. In this connection, the rain intensity and vehicle speed are taken into account.

The activity of the windshield wiper system allows for conclusions on the rain intensity. The windshield wiper system is controlled by the front SAM control unit. In the case of high windshield wiper system activity, the front SAM control unit transmits the "Rain closing function" request via the interior CAN to the panoramic sliding sunroof control unit. The instrument cluster sends the vehicle speed to the panoramic sliding sunroof control unit via user interface CAN, electronic ignition lock control unit and interior CAN. The panoramic sliding sunroof control unit evaluates the data and accordingly actuates the panoramic sliding sunroof motor.

IMPORTANT Dynamic rain closing can be interrupted by momentarily actuating the roof system switch and the panoramic sliding roof can be adjusted to any position.

Additional function requirements for speed-dependent tilt adjustment 

Speed-dependent tilt adjustment 

If the panoramic sliding sunroof is fully opened in the tilt position, it automatically lowers at higher speeds. Depending on the driven speed, the panoramic sliding sunroof is lowered in two stages. The wind noises in the vehicle interior are thus reduced. Where a defined speed threshold is undershot, the panoramic sliding sunroof automatically raises again in the tilt position.

The instrument cluster sends the vehicle speed to the panoramic sliding sunroof control unit via user interface CAN, electronic ignition lock control unit and interior CAN. The panoramic sliding sunroof control unit then accordingly actuates the panoramic sliding sunroof motor.

Additional function requirements for the memory function 

Memory function 

At the end of a manual adjustment, the positions of the roller sun blind and panoramic sliding sunroof are saved in the panoramic sliding sunroof control unit.

During the automatic opening of the roller sun blind and/or panoramic sliding sunroof, the last saved positions are moved to.

  Electrical function schematic for panoramic sliding sunroof   PE77.20-P-2052-97DCA 
  Overview of system components, panoramic sliding sunroof   GF77.20-P-9991FH 
scientia non olet · About LEMON Manuals