Power Windows, Function - GF72.29-P-0001FH

Model 238 

up to model year 2021 

Courtesy of MERCEDES-BENZ USA

Function requirements, general 

• No overvoltage or undervoltage
• Circuit 15R r circuit 15 ON o run-on time active

Run-on:

If terminal 15R is switched off, the power windows can still be operated for 5 min. If, during the run-on time, the circuits status or the door status is changed, the run-on time starts again.

The status of circuit 15 is sent by the electronic ignition lock control unit via interior CAN to the front door control units and rear door control unit.

The front door control units sense the status of the front doors (open or closed).

Power windows, general 

For ventilation of the passenger compartment, the side windows of the vehicle can be opened and closed electrically.

Operation possibilities:

• Driver-side power window and outside mirror adjustment switch group
  • Left front power window switch
  • Right front power window switch
  • Left rear power window switch
  • Right rear power window switch
• Passenger-side power window switch
• Left rear power window switch
• Right rear power window switch

Press and hold down power window switch to perform a manual function. To start an automatic function it is sufficient to momentarily actuate beyond the catch point. Actuation takes place for as long (maximum 25 s) as the corresponding request is pending or until the side window reaches the lower or upper stop.

The priority of possible functions depends on their requirement. A command with higher priority is performed if a function with lower priority is currently active. A lower priority function is interrupted first and is accomplished only after the second valid request. If a command with lower priority is still present after completion of an operation request with higher priority, the former command is ignored. It is first necessary for the controls to recognize non-actuation of the lower priority request before the corresponding function can be activated.

Priority sequence:

• Driver-side power window and outside mirror adjustment switch group
• Remaining power window switches
• Actuation via diagnostic tester
• Close side windows via PRE-SAFE®
• Open side window with crash ventilation
• Convenience opening/closing through central locking
• Comfort opening/closing via air recirculation function (except code (494) USA version)

The power window functions comprise the following partial functions:

• Normalizing 
• Manual raising and lowering 
• Automatic raising and lowering 
• Short stroke 
• Actuation by PRE-SAFE® 
• Crash ventilation 
• Excess force limiter 
• Lock-up reverse 
• Overheating protection 
• Childproof locks 

Normalizing 

Normalization is the basis for assignment of the current position relative to each side window position as detected by the front door control unit or rear door control unit. To this end, the relevant side window must be fully closed manually, and the power window switch must continue to be pressed for approx. 300 ms. When the power window switch is then released, the side window lowers approx. 20 mm. The side window must now be closed fully once more within 4 s and the power window switch held for another 300 ms.

The corresponding signal path is described in the chapter "Manual run-up/run-down".

The location counter is set to 0 in the corresponding front door control unit or rear door control unit and the normalization procedure is completed. The location counter evaluates the signals from the Hall sensor integrated in the corresponding power window motor. The counter status is increased when opening and decreased when closing the side windows.

The ratio between counter status and armature rotations of the power window motor is 4: 1.

The power windows are denormalized under the following conditions:

• Position counter status greater than maximum adjustment range
• Position counter status going beyond zero point tolerance for stored zero point
• No Hall sensor signals when power window motor in question is actuated

The reason for denormalization is stored in the corresponding front door control unit and rear door control unit. When the power windows are denormalized, only the manual raising and lowering functions are possible.

Normalization is a basic requirement to use the entire power window functions.

Manual raising and lowering 

Actuate and hold down corresponding power window switch to the first catch point or beyond in the opening or closing direction. Actuation lasts as long (maximum 25 s) as the corresponding request is pending or until the lower or upper stop is reached.

The glass pane reduces the speed of movement when it runs into the upper seal. As from June 1, 2018, the speed of movement will not be reduced at a vehicle speed above 120 km/h.

Front side window in driver side: 

The status of the left front power window switch in the power window switch group and driver side outside mirror adjustment are read in by the left front door control unit via the left door LIN. The left front door control unit then actuates the left front door power window motor and directly reads in the signals from the Hall sensor.

Front side window in passenger side: 

• The status of the passenger side power window switch is read directly in by the right front door control unit. The right front door control unit then actuates the right front door power window motor and directly reads in the signals from the Hall sensor.
• The status of the right front power window switch in the power window switch group and driver side outside mirror adjustment is read in by the left front door control unit via the left door LIN and transmitted to the right front door control unit via the interior CAN. The right front door control unit then actuates the right front door power window motor and directly reads in the signals from the Hall sensor.

Rear side window: 

• The status of the power window switch is read in directly by the rear SAM control unit. The rear control unit then actuates the relevant rear power window motor and reads in the signals from the Hall sensor directly.
• The signals from the rear power window switch in the driver-side switch group are read in by the left front door control unit via left front door LIN and transmitted to the rear door control unit via the interior CAN. The rear control unit then actuates the relevant rear power window motor and reads in the signals from the Hall sensor directly.

Additional function requirements for automatic raising and lowering 

• Power windows normalized
• Child safety lock switched off

Automatic raising and lowering 

The corresponding power window switch must be actuated just beyond the first catch point in the "opening" or "closing" direction and then released.

The remaining function sequence corresponds to that of manual raising and lowering.

Actuation of the power window motors is discontinued automatically upon reaching the bottom or top stop. The automatic reserving function is active during automatic raising.

additional function requirements for short stroke 

• Power windows normalized

Short stroke 

When the front door is opened, the side window in the front door and the associated rear side window are lowered to the short stroke position.

After closing the front door, the side windows are closed. The front door control unit for the front side window or the rear control unit for the rear side window is responsible for control.

Short stroke: 

• Front side window approx. 4 mm
• Rear side window approx. 4 mm

The corresponding front door control unit senses the status of the corresponding front door and directly actuates the front door power window motor. The corresponding front side window is lowered to the short stroke position. Then the corresponding front door control unit transmits the request "Actuate short stroke position" to the rear control unit via the interior CAN. The rear control unit then directly actuates the rear power window motor. The corresponding rear side window is lowered to the short stroke position.

Additional function requirements for actuation by PRE-SAFE® 

• Power windows normalized
• Side windows opened further than PRE-SAFE® position

Actuation by PRE-SAFE® 

If the Electronic Stability Program detects an unstable vehicle status (e. g. understeer or oversteer), the side windows are closed to a defined position (50 ± 4 mm before upper stop) to minimize the risk of injury.

The electronic stability program transmits the information for the PRE-SAFE® status and the request for PRE-SAFE® adjustment via chassis FlexRay, electronic ignition lock control unit and interior CAN to the front door control units and rear door control unit. The corresponding front door control unit then actuates directly the front door power window motor. The rear door control unit directly actuates the rear power window motors.

Actuation by PRE-SAFE® is interrupted in case of:

• Active automatic reversing function
• Blockage detection
• Request from corresponding power window switch

Additional function requirements for crash ventilation 

• Power windows normalized
• Front side windows closed more than 50 ± 4mm before upper stop

Crash ventilation 

Smoke particles are produced in the vehicle interior when the pyrotechnical restraint equipment is triggered. To ensure that these smoke particles are removed quickly, the front side windows are automatically opened to a defined position (50 ± 4mm before upper stop) in event of an accident.

The supplemental restraint system control unit sends the crash signal over the user interface CAN, electronic ignition lock control unit and interior CAN to the front door control units. The front door control units then actuate the front door power window motors directly.

The crash ventilation is interrupted on request by the power window switch. The crash ventilation is inhibited when the PRE-SAFE® function is activated.

Additional function requirements for excess force limiter 

• Window position in the range from 3 to 230 mm (clear opening)
• Power windows normalized

Excess force limiter 

The excess force limiter function operates when the window is raised automatically or manually, however, at different sensitivity levels (escalation stages). The power consumption of the power window motor serves as a reference for excessive force.

The system is designed adaptively to prevent mechanical sluggishness being evaluated as pinching. This means that the system recognizes sluggishness by the increased power consumption of the respective power window motor, and calculates an additional force of 10 N for the next request. This ensures a constant speed when opening or closing the power windows even in the face of advanced wear or external influences such as moisture and ice.

Adaption is limited to a maximum value of 80 N. The individual escalation stages depend on the operating request and history and are shown in the table below.

Manual closing	1. Actuation (escalation stage 1)	2nd actuation (escalation stage 2)	3rd actuation (escalation stage 3)
Holding power window switches	Stop at 100 N (+15 N)	Stop at 130 N (+15 N)	Actuation remains active
Releasing power window switches	Reverse 20 mm (+5 mm)	Reverse 20 mm (+5 mm)	Actuation stopped
Automatic closing
Releasing power window switches	Stop at 60 N (-10 N); Reverse 125 mm (+5 mm)	Stop at 80 N (-10 N); Reverse 125 mm (+5 mm)	Only manual raising possible

If the power window switch is actuated again within 2 s after reversing is finished, the status changes. If the power window switch is actuated again after a time of 2 s, escalation stage 1 (1st actuation) is started.

If pinching is recognized during automatic raising triggered by the comfort closing function via the air recirculation function, the corresponding front door control unit or rear door control unit starts with escalation stage 1 (1st actuation).

If pinching is recognized during automatic raising, triggered by the KEYLESS-GO function (with CODE 889 (Keyless-Go)) or the closing side window function by PRE-SAFE®, the corresponding front door control unit or rear door control unit starts with escalation stage 2 (2nd actuation).

If power windows are not normalized, the excessive force limiter is active starting at a pinching force of 100 N. The side window always reverses when it runs into the upper seal.

On power windows which have not been normalized, the excess force limiter is deactivated within a short time after two closing requests. This allows normalization at the upper stop.

Mechanical vibrations caused by bad road conditions are not recognized as pinching and do not lead to reversal of the corresponding power window. The "bad road recognition" required for this purpose is therefore activated starting at a speed of 8 km/h.

Additional function requirements for lock-up reversing 

• Power windows normalized

Lock-up reverse 

If the respective front door control unit or rear door control unit does not recognize within 150 ms (+20 ms) a change in the Hall sensor signals or an increase in force of 60 N from the set distance already traveled while the side window is closing, this is evaluated as blocking. Closing is stopped immediately and the side window is opened 20 mm. The lock-up reversing function depends on the type of rolling up. Escalation stages for excess force limiter function apply.

Overheating protection 

The protection of the power window motors is guaranteed by a thermal protection software in the corresponding front door control unit or rear door control unit. The software simulates temperature characteristics depending on the operating time. The parameters required for this were determined in tests and are stored in the associated front door control unit or rear door control unit..

The permissible ambient temperature range of the power window motors is: -40 to +85 °C.

Childproof locks 

When the child safety lock is switched on, the rear side windows cannot be opened and closed by actuating the rear power window switch. Actuations already activated are interrupted immediately by the rear power window motors. The child safety lock can be switched on and off via the rear side window child safety switch in the power window switch group and driver side outside mirror adjustment.

The status of the rear side window child safety lock is read by the left front door control unit via the front door LIN. The left front door control unit transmits the status to the rear SAM control unit via the interior CAN.

The rear side window child safety lock switch signals the driver that the child safety lock is activated. The left front door control unit transmits the request to actuate the LED via the left front door LIN to the rear side window child safety switch.

If the position of the rear side window child safety lock switch can no longer be read with certainty, the child safety lock function is regarded as permanently switched on.

	Electrical function diagram for power windows		PE72.29-P-2050-97DCA
	Overview of system components for windows and sightproofing		GF67.00-P-9999FH