LEMON Manuals: Even more car manuals for everyone
Home >> Mercedes Benz >> 2017 >> GLS350d >> Repair and Diagnosis >> Body & Frame >> Sun Roof/T-Top/Convertible Top >> Sliding Roof, Soft Top, Top Attachments - 166 Chassis >> Basic Knowledge >> Electric Power Sliding Roof, Function >> (Electric Power Sliding Roof, Function - GF77.20-P-0007GR)

(Electric Power Sliding Roof, Function - GF77.20-P-0007GR)

MODEL 166 

up to model year 2016 

with CODE 414 (Power glass tilting/sliding roof) 

G14136595Courtesy of MERCEDES-BENZ USA

Function requirements, general 

IMPORTANT Detailed information on the operating state of the transport mode is given in the separate function description for energy management.

Sliding roof, general 

The sliding roof is a combined sliding/tilting roof. The sliding roof function drops the sliding roof down and moves it backwards into the headliner; the power tilting roof function raises the sliding roof at the rear.

Operation occurs by means of the sliding roof switch on the overhead control panel control unit.

Overheating protection:

The sliding roof motor is equipped with a thermal protection switch to protect against thermal overlaod. The sliding roof system motor is not designed for continuous operation.

The sliding roof motor is switched off if the maximum permissible operating time is exceeded (overheating protection). Then actuation is inhibited for the remainder of the cooling phase. The overheating protection is not activated during the automatic reversing function.

Recognition of switch signals:

Actuation of the sliding roof switch is clearly recognized only after t = 40 ± 10 ms. The maximum actuation time is t ≥ 20 s. After t 60 s, the system recognizes a "stuck" sliding roof switch. A new actuation (triggered via the sliding roof switch) can only be performed again after detecting that the sliding roof switch is in the rest position.

IMPORTANT The comfort functions are control possibilities allowing central opening and closing together with the side windows from one control point. These comfort functions are described in the partial function "Convenience feature (CF [KFB]), function" within the "Theft protection and lock function description" function.

The sliding roof function comprises the following partial functions:

Additional function requirements for position monitoring 

Function sequence for position monitoring 

The sliding roof control module monitors the position of the sliding roof by evaluating the signals from the following sensors:

The Hall sensors are arranged offset by 90° on the axis of the sliding roof motor. The position of the sliding roof is determined by counting the Hall sensor pulses.

The zero position (sliding roof opened in tilt position) is set by normalizing.

Additional function requirements for normalization 

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

The left front door control unit sends the status of the left front door over the interior CAN to the sliding roof control module.

The right front door control unit sends the status of the right front door over the interior CAN to the sliding roof control module.

Denormalization takes place:

IMPORTANT The position of the sliding roof cannot be determined in the denormalized condition. The function is then limited to manual closing or opening.

Function sequence for normalization 

Normalizing is the basis for assigning the current position to the position of the sliding roof sensed by the sliding roof control module.

The sliding roof must be completely open for this.

The sliding roof must be opened manually to the tilt position and to the rear sliding roof position until the mechanical limit stop is reached using the sliding roof system switch and the roof system switch must be kept actuated. The signal must be present for at least t = 1 s. By evaluating the signals of the Hall sensors, the sliding roof control module recognizes the blockage and sets the corresponding location counter to zero.

When normalized, the sliding roof system motor is switched off by the sliding roof module before the mechanical stop is reached during automatic opening and closing.

Additional function requirements for blockage detection 

Function sequence for lockup recognition 

Blockage is detected if signals are no longer detected from the Hall sensors for a period of t = 350 ms during an adjustment request.

If the blockage is recognized in the closing direction, the sliding roof motor is first stopped and then actuated in the opposite direction.

If the blockage is recognized in the opening direction, the sliding roof motor is stopped and no longer actuated.

Additional function requirements for automatic reversing function 

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

The left front door control unit sends the status of the left front door over the interior CAN to the sliding roof control module.

The right front door control unit sends the status of the right front door over the interior CAN to the sliding roof control module.

Function sequence for automatic reserving function 

The automatic reversing function is based on a comparison between the current force required by the sliding roof motor (determined by the current consumption) and the force value measured during the learn-in run or during adaptation.

If this comparison exceeds a certain limit with value during a closing operation, this is detected as pinching by the sliding roof control module.

IMPORTANT During a learn-in run all of the sliding roof closing procedures are accomplished in the normalized condition. The sliding roof control module adapts to change in the power consumption resulting from increased sluggishness (e.g. dirt in the mechanical system).

If a pinching is detected during an opening procedure, the sliding roof is simply stopped. If pinching is recognized during closing, the sliding roof motor is first stopped and then reversed (actuated in opposite direction).

Special case, manual closing:

If the sliding roof switch is actuated in the closing direction within t = 2 s after reversing, the sliding roof control module allows increased force. The automatic reversing function is deactivated if another request from the sliding roof switch is present.

Additional function requirements for opening/closing sliding roof 

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

The left front door control unit sends the status of the left front door over the interior CAN to the sliding roof control module.

The right front door control unit sends the status of the right front door over the interior CAN to the sliding roof control module.

Function sequence for opening/closing sliding roof 

The sliding roof can be opened and closed manually or automatically.

The sliding roof is opened or closed manually by actuating the sliding roof switch to the first detent.

The sliding roof is fully opened or closed automatically by actuating the sliding roof switch past the first detent.

The overhead control panel control unit directly reads in the status of the sliding roof switch and transmits it to the SAM control unit via the roof LIN. The rear SAM control unit transmits the status of the sliding roof switch to the sliding roof control module via the interior CAN. The sliding roof control module reads in this status and actuates the sliding roof motor according to the selected actuation direction for the time the request is present. The automatic reversing function is active during closing.

Automatic adjustment is aborted if the roof switch is actuated again. The automatic reversing function is active during closing.

IMPORTANT When the sliding roof is denormalized, it can only be actuated in steps of t = 0.5 s each.

Additional function requirements for rain closing 

Function sequence for rain closing 

The rain closing function is triggered if moisture is recognized on the windshield by the rain/light sensor. The SAM control unit reads in the data of the rain/light sensor via the roof LIN and transmits it to the sliding roof module via the interior CAN. It actuates the sliding roof motor. The sliding roof is moved to the tilt position. Monitoring is then no longer performed.

IMPORTANT Rain closing is performed even if the run-on time (t = 6 h) has expired or the voltage or temperature is no longer within the operating range of the rain/light sensor.

IMPORTANT MODEL 166 up to model year 2016 with CODE 414 (Power glass tilting/sliding roof)

with CODE 882 (Interior monitoring (with ATA [EDW] only))

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

  Electrical function schematic for sliding roof   PE77.20-P-2054-97NAA 
  Overview of system components for electric power sliding roof   GF77.20-P-9989GR