Keyless Go, Function - GF80.61-P-0005RFM

WARNING: This page is about a different car, the 2023 Mercedes-Benz GLC300, 2022 Mercedes-Benz GLC300, 2021 Mercedes-Benz GLC300, 2020 Mercedes-Benz GLC350e, and 2020 Mercedes-Benz GLC300. However, it is still accessible from the selected car via links, so may be relevant.

Model 205 as of Model year 2019

Model 253 (except 253.99) as of Model year 2020

Model 253.99

KEYLESS-GO start function (except code 889 (KEYLESS-GO))

Courtesy of MERCEDES-BENZ USA

Courtesy of MERCEDES-BENZ USA

KEYLESS-GO (with CODE 889 (KEYLESS-GO))

KEYLESS-GO, general

The KEYLESS-GO comfort functions allows keyless locking/unlocking of the vehicle (with code 889 (KEYLESS-GO)) as well as starting or shutting down the engine. Carrying the transmitter key or with code 896 (Vehicle access and drive authorization via mobile phone) a suitable mobile phone with near field communication function (NFC) is sufficient.

The partial function digital key in smartphone (with code 896 (Vehicle access and drive authorization via mobile phone)) is described in a separate document.

The KEYLESS-GO comfort function can be deactivated by a double clock on the lock button of the transmitter key. Deactivation is acknowledged by the LED in the transmitter key illuminating for a longer period of time. The KEYLESS-GO comfort function is activated by actuating any transmitter key or by communication between the transponder in the center console and the transmitter key.

Limp-home function:

If the battery of the transmitter key is discharged or the wireless connection is interfered, position transmitter key at point marked in the stowage compartment of the front center console to start the engine.

Operation of the central locking (CL) via the transmitter key remains possible parallel to the KEYLESS-GO functions.

The KG system contains the following partial functions:

Function sequence for position finding of transmitter key
Function sequence for locking/unlocking (with code (889) KEYLESS-GO)
Function sequence for engine start/stop

Model 205 as of Model year 2019 with code 551 (Anti-theft warning system)

with code 889 (KEYLESS-GO)

Model 205 as of Model year 2019 with code 551 (Anti-theft warning system) with code 893 (KEYLESS-GO)

Model 253 (except 253.99) as of Model year 2020 with code 551 (Anti-theft warning system)

with code 889 (KEYLESS-GO)

Model 253 (except 253.99) as of Model year 2020 with code 551 (Anti-theft warning system)

with code 893 (KEYLESS-GO)

Model 253.99 with code 551 (Anti-theft warning system)

with code 889 (KEYLESS-GO)

Model 253.99 with code 551 (Anti-theft warning system)

with code 893 (KEYLESS-GO)

The anti-theft alarm (ATA [EDW]) behaves in the same way as if the car were unlocked and locked with the transmitter key.

Function sequence for position finding of transmitter key

To reliably or securely realize the locking/unlocking (with CODE 889 (KEYLESS-GO)) and engine start/stop function, it is necessary to determine the position of and authorize the transmitter key.

The following illustration indicates the components with the KEYLESS-GO Control unit uses to detect the area around the vehicle or in the vehicle where the transmitter key is located.

KEYLESS-GO start function (except code 889 (KEYLESS-GO)), shown on Model 205.0

Courtesy of MERCEDES-BENZ USA

The KEYLESS-GO Control unit transmits coded requests to the transmitter key via the center console KEYLESS-GO antenna and the KEYLESS-GO trunk antenna. The transmitter key decodes these requests and transmits coded responses, when it is in area C or D. The KEYLESS-GO Control unit receives the transmitter key responses via the rear window antenna (Model 205 (except Model 205.4), Model 253), the windshield antenna (Model 205.4), and the antenna amplifier FM 1, AM, CL, and KEYLESS-GO and subjects these to plausibility checks and transmits them to the electronic ignition lock Control unit via the interior CAN. If the evaluation is positive, the electronic ignition lock Control unit authorizes the transmitter key.

KEYLESS-GO (with CODE (889) KEYLESS-GO), shown on Model 205.0

Courtesy of MERCEDES-BENZ USA

The position is determined when a capacitive sensor in a KEYLESS-GO door handle or the trunk lid/liftgate external operation switch is actuated.

The KEYLESS-GO Control unit directly reads in the signals from the capacitive sensors.

The rear SAM Control unit reads in the status of the trunk lid/liftgate external operation switch directly and sends this via interior CAN to the KEYLESS-GO Control unit.

Then the KEYLESS-GO Control unit transmits coded requests to the transmitter key via the KEYLESS-GO antennas. The transmitter key decodes these requests and transmits coded requests correspondingly when it is located in area A, B, C or D. The KEYLESS-GO Control unit receives the transmitter key responses via the rear window antenna (Model 205 (except Model 205.4), Model 253), the windshield antenna (Model 205.4), and the antenna amplifier FM 1, AM, CL, and KEYLESS-GO and subjects these to plausibility checks and transmits them to the electronic ignition lock Control unit via the interior CAN. If the evaluation is positive, the electronic ignition lock Control unit authorizes the transmitter key.

If the vehicle is loaded with unusual material (high volumes of metal) the long wave frequencies emitted by the KEYLESS-GO antennas for the KEYLESS-GO Control unit are reflected or absorbed to a high degree, which can lead to erroneous detection. The maximum overlap between the detected inside and outside area (measured at the side window) is approx. s = 10 cm depending on the vehicle contour. I.e., above s = 10 cm, the position detection is correct and the transmitter key is definitively located in the detected range. Below s = 10 cm (Gray area) the position detection for the transmitter key may be faulty and this means it is not possible to determine reliably whether the transmitter key is located inside or outside the vehicle.

Additional function requirements for locking/unlocking (with code (889) KEYLESS-GO)

Circuit 15C OFF (circuit 15R permissible when locking):
The electronic ignition lock Control unit transmits the circuit status to the KEYLESS go Control unit via the interior CAN.
- The transmitter key is located outside the vehicle (maximum of approx. s = 1 m distance to a control element)
Function sequence for locking/unlocking (with code (889) KEYLESS-GO)

The locking/unlocking function allows the vehicle to be opened and closed via the CL.

The following control elements are available:
To lock and unlock:
- Driver door KEYLESS-GO door handle
- Front passenger door KEYLESS-GO door handle
To open/close trunk lid:
- Trunk lid/liftgate external operation switch (open only)
- Rear switching module (with CODE 871 (HANDS-FREE ACCESS)) (opening/closing)
To lock:
- Trunk lid/liftgate control button (with code 881 (Remote trunk closing))

The sensor units in the KEYLESS-GO door handles are switched off when circuit 15 is switched on. Activation takes place when circuit 15 is switched off and a door is opened. During a remote start (for pre-entry climate control with code 494 (USA version)) or if driver absence is detected, the sensor units are not switched off.

The locking/unlocking function comprises the following subfunctions:

Function sequence for preadjustment of unlocking mode
Function sequence for locking/unlocking one vehicle door
Function sequence for acoustic locking feedback
Function sequence for optical locking feedback
Function sequence for unlocking and opening trunk lid
Function sequence for closing trunk lid and locking vehicle

Function sequence for preadjustment of unlocking mode

Basically the following types of unlocking are differentiated:

Globally unlocking:
- The entire vehicle can be unlocked by reaching into or pulling a KEYLESS-GO door handle.
Selective unlock (only possible at the driver door):
- By reaching into the driver door KEYLESS-GO door handle or by pulling driver door KEYLESS-GO door handle, only the driver door is unlocked and the opening request for the fuel filler flap is enabled.

Operating the trunk lid/liftgate external operation switch only opens the trunk lid. If a passenger KEYLESS-GO door handle is operated during selective unlocking, global opening takes place.

Simultaneously pressing the unlock button and the lock button on the transmitter key for t = 5 s switches the system between two types of unlocking. The LED on the transmitter key comes on twice to confirm this change.

Function sequence for locking/unlocking one vehicle door

Unlocking possibilities:

Reaching any KEYLESS-GO door handle
Pulling any KEYLESS-GO door handle

Option for opening trunk lid:

Operate the trunk lid/liftgate external operation switch
"Kicking movement" beneath rear bumper (Rear switching module (with code (871) HANDS-FREE ACCESS))

Locking possibilities:

Touching outside of KEYLESS-GO door handle or
Actuating sensor on KEYLESS-GO door handle

Example globally unlocking at left front door (left-hand drive vehicles):

When you reach into the driver door KEYLESS-GO door handle, the capacitive sensor (recessed sensor area) in the door handle recognizes this. The KEYLESS-GO Control unit reads in the signal from the capacitive sensor and transmits a wake-up signal to the transmitter key via the left door KEYLESS-GO antenna.

The transmitter key transmits its access authorization code and its position to the KEYLESS-GO Control unit via the rear window antenna (Model 205 (except Model 205.4), Model 253), the windshield antenna (Model 205.4), the antenna amplifier FM 1, AM, CL, and KEYLESS-GO.

The KEYLESS-GO control transmits this data to the electronic ignition lock Control unit via the interior CAN. The electronic ignition lock Control unit checks the access authorization code.

If it is defined as valid, the electronic ignition lock Control unit transmits the request "Open CL" via the interior CAN to the following Control units:

Front SAM Control unit (for locking feedback)
Rear SAM Control unit
Left front door Control unit
Right front door Control unit

The left front door Control unit unlocks the left front door lock via the left front doors central locking motor. The right front door Control unit unlocks the right front door lock via the right front door central locking motor.

Opening the trunk lid via the trunk lid/liftgate external operation switch is enabled accordingly by the rear SAM Control unit. The rear SAM Control unit enables the opening request from the tank cap central locking actuator.

On vehicles with code (885) Extended theft protection, the following components are actuated additionally:

Left front door additional door lock actuator motor in left front door lock
Right front door additional door lock actuator motor in right front door lock

Model 205 as of Model year 2019 with code 885 (Enhanced anti-theft protection)

Model 253 (except 253.99) as of Model year 2020 with code 885 (Enhanced anti-theft protection)

Model 253.99 with code 885 (Enhanced anti-theft protection)

Any person locked inside can trigger the horn function after the vehicle is locked by actuating the horn contact plate (S4/2), thus drawing attention to himself or herself.

The vehicle cannot be locked if a door is open.

Function sequence for acoustic locking feedback

The acoustic closing feedback function can be activated and deactivated over the control menu in the head unit. The following options are available for navigating in the control menu:

Except with code 446 (Touchpad only) it is possible to navigate with the audio/COMAND control panel. The audio/COMAND control panel (except code 446 (Touchpad only)) transmits the corresponding signals via telematics CAN to the head unit.
With code 446 (Touchpad only) or code 448 (Touchpad) navigation is possible with the touchpad. The touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) transmits the corresponding control signals via telematics CAN to the head unit.
Navigation can be performed by voice control. The driver hands-free system microphone is read directly by the head unit.
Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The head unit finger navigation pad and the "Back" button transmit the corresponding operation signals via the steering wheel electronics, steering wheel CAN, steering column tube module Control unit, suspension FlexRay, electronic ignition lock Control unit and the user interface CAN to the head unit.
With code 246 (Analog clock), the control menu can be called up with the Vehicle button in the upper control panel Control unit. The upper control panel Control unit transmits the status of the vehicle button via LCP-LIN, audio/COMAND control panel (except code 446 (Touchpad only)) or touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) and Telemachus CAN to the head unit.

The head unit generates the corresponding image data, transmits a switch-on request via the telematic CAN to the audio/COMAND display and transfers the image data via the HSVL line to the audio/COMAND display. Then the head unit sends the status of the acoustic locking feedback function via user interface CAN, electronic ignition lock Control unit and interior CAN to the front SAM Control unit. When the acoustic locking feedback function is activated, the front SAM Control unit momentarily actuates the left horn and the right horn via the horn relay after successful locking. For this purpose the electronic ignition lock Control unit sends the "Lock" request via interior CAN to the front SAM Control unit.

The horns actuated once during locking.

There is no signal for unlocking. If, when locking, a door, the trunk lid or the tank cap is open, an acoustic closing feedback is not output.

Function sequence for optical locking feedback

After the CL is locked or unlocked successfully, a visual feedback is output via the turn signals.

The electronic ignition lock Control unit transmits the request "Lock" or "Unlock" to the front SAM Control unit via the interior CAN. The front SAM Control unit then actuates the hazard warning flasher function by outputting the flasher frequency via the interior CAN. All turn signals are actuated synchronously on the vehicle.

One flashing cycle is output when unlocking. Three flashing cycles are output when locking.

If another door or the trunk lid is opened when locking a door, visual locking feedback is not accomplished.

Additional function requirements for unlocking and opening trunk lid

Vehicle (trunk lid) locked

Function sequence for unlocking and opening trunk lid

Trunk lid/liftgate external operation switch:

When the trunk lid/liftgate external operation switch is pressed, the trunk lid is unlocked and opened. The rear SAM Control unit reads in the status of the trunk lid/liftgate external operation switch directly and sends this via interior CAN to the KEYLESS-GO Control unit. With CODE 871 (HANDS-FREE ACCESS):

The function is actuated by foot motion ("kicking motion") in the rear of the rear switching module below the bumper. The rear switching module reads in the rear switching module sensor signals directly, evaluates them and transmits the relevant request to the KEYLESS-GO Control unit via the KEYLESS-GO LIN.

In both cases the KEYLESS-GO Control unit then actuates the trunk KEYLESS-GO antenna, which transmits a wakeup signal to the transmitter key. The transmitter key transmits its access authorization code and its position to the KEYLESS-GO Control unit via the rear window antenna (Model 205 (except Model 205.4), Model 253), the windshield antenna (Model 205.4), the antenna amplifier FM 1, AM, CL, and KEYLESS-GO. The KEYLESS-GO Control unit transmits the access authorization code via the interior CAN to the electronic ignition lock Control unit. If the access authorization is valid, the electronic ignition switch Control unit sends request "Open trunk lid" to the rear SAM Control unit via interior CAN. The rear SAM Control unit then actuates the trunk lid/liftgate lock motor in the trunk lid/liftgate lock to unlock the trunk lid.

Additional function requirements for closing trunk lid and locking vehicle

Driver door closed

Function sequence for closing trunk lid and locking vehicle

Trunk lid/liftgate control button (with code 881 (Remote trunk closing)):

The rear SAM Control unit directly reads in the status of the trunk lid/liftgate control button and transmits it to the trunk lid control Control unit via the interior CAN, which starts closing the trunk lid.

With CODE 871 (HANDS-FREE ACCESS):

Closing the trunk lid is triggered by moving the foot ("Kick movement") in the area of the rear switching module sensors below the bumper, however, the trunk lid cannot be locked. The rear switching module directly reads in the signals from rear switching module sensors, evaluates them and transmits the corresponding request to the KEYLESS-GO Control unit via the KEYLESS-GO LIN.

Additional function prerequisites for Engine Start/Stop

The transmitter key is located in the vehicle interior

Function sequence for engine start/stop

The function engine start/stop enables to engine to be started and switched off via the KEYLESS-GO start/stop button.

The partial function start/stop engine comprises the following partial functions:

Function sequence for interrogation of transmitter key
Function sequence for starting engine
Function sequence for display of fault messages
Function sequence for circuit switching
Function sequence for shutting off engine

Function sequence for interrogation of transmitter key

The KEYLESS-GO Control unit starts the check for an authorized transmitter key under the following conditions:

When the final door is closed
When starting off (v > 0 km/h), if a door or the trunk lid is not closed.

If the vehicle stops and no door is opened, no new interrogation takes place as well.

If, to start the engine, no valid transmitter key is recognized in the vehicle interior after checking, the instrument cluster outputs the message "Key not recognized" in white lettering. If a transmitter key is not recognized in the vehicle interior when starting the vehicle, the message "Key not recognized" appears in red lettering in the instrument cluster. In this case it is possible to switch off the engine, however, it cannot be started. The message remains until it is acknowledged by the driver by changing the door status or with circuit 15 Off.

Additional function requirements for starting engine

Transmission in "P" or "N" position (transmission 725):
The fully integrated transmission Control unit sends the transmission selector lever position to the electronic ignition lock Control unit via drive train CAN, the powertrain Control unit and the chassis FlexRay.
Foot brake actuated (transmission 725):
The electronic stability program Control unit reads in the status of the brake light switch (except hybrid vehicles) or the pedal angle sensor signal (hybrid vehicles) directly and transmits it to the electronic ignition lock Control unit via the suspension FlexRay.
Clutch operated (transmission 716):
The CDI Control unit or the ME-SFI Control unit transmits the clutch pedal sensor signal to the electronic ignition lock Control unit via the engine CAN, powertrain Control unit, and suspension FlexRay.

Function sequence for starting engine

The engine is started when the KEYLESS-GO start/stop button is pressed.

The electronic ignition lock Control unit directly reads in this request and transmits the status "Start/stop button pressed" via the interior CAN to the KEYLESS-GO Control unit.

The KEYLESS-GO Control unit evaluates this and transmits wake-up and location-finding signals to the transmitter key via the center console KEYLESS-GO antenna. The transmitter key transmits its drive authorization code and its position to the KEYLESS-GO Control unit via the rear window antenna (Model 205 (except Model 205.4), Model 253), the windshield antenna (Model 205.4), the antenna amplifier FM 1, AM, CL, and KEYLESS-GO. The KEYLESS-GO control transmits this data to the electronic ignition lock Control unit via the interior CAN. The electronic ignition lock Control unit checks the drive authorization code. If this is defined as valid, the electronic ignition lock Control unit sends the status circuit 50 On via the chassis FlexRay, the drive train Control unit and engine CAN to the CDI Control unit or the ME-SFI [ME] Control unit. In Model 253.99, the electronic ignition lock Control unit transmits the status of circuit 50 ON to the powertrain Control unit via the suspension FlexRay.

Function sequence for display of fault messages

The electronic ignition lock Control unit sends the request to output fault messages via user interface CAN to the instrument cluster.

The following situations lead to the output of fault messages:

If the search for a key for drive authorization is unsuccessful, the instrument cluster displays the message "Store key in marked stowage box/tray" in white lettering.
If the key search for drive authorization by transponder function is not successful, the instrument cluster outputs the message "Key not recognized" in white lettering.
If no transmitter key is recognized in the vehicle interior after actuating the KEYLESS-GO start/stop button, the instrument cluster outputs the message "Key not recognized" in while lettering. The start attempt is not started. The status of the circuit remains unchanged.
If the transmitter key is not recognized in the vehicle interior when the last door or the trunk lid is closed when the drive train is active or when starting off with an open door or open trunk lid, the instrument cluster outputs the message "Key not recognized" in red lettering.

Function sequence for circuit switching

If the foot brake is not depressed when the KEYLESS-GO start/stop button is actuated, only circuit 15R is switched on. Repeated actuation of the KEYLESS-GO start/stop button activates circuit 15. Actuating again, switches off circuit 15R and circuit 15. When the driver door is closed, circuit 15C remains switched on for t = 30 min.

Function sequence for shutting off engine

When the KEYLESS-GO start/stop button is pressed when the engine is running, the engine is requested to shut down. The electronic ignition lock Control unit detects when the KEYLESS-GO start/stop button is pressed and transmits the status "Start/stop button pressed" to the KEYLESS-GO Control unit via the interior CAN. The KEYLESS-GO Control unit evaluates this and transmits the request "Shut off engine" via the interior CAN, electronic ignition lock Control unit and chassis Flex-Ray, drive train Control unit and engine CAN to the CDI Control unit and ME-SFI Control unit.

The CDI Control unit or ME-SFI Control unit then shuts off the engine depending on the vehicle speed.

In Model 253.99, the KEYLESS-GO Control unit transmits the "engine stop" request to the powertrain Control unit via the interior CAN, electronic, ignition lock Control unit, and suspension FlexRay. The powertrain Control unit then stops the engine, depending on the vehicle speed.

Switching off engine depending on vehicle speed:

Speed v < 3 km/h: Engine switched off immediately.
Speed v > 3 km/h: Engine is switched off only after pressing KEYLESS-GO start/stop button for a longer period of time (t > 3 s).

The vehicle speed is sent by the instrument cluster via user interface CAN, the electronic ignition lock Control unit and interior CAN to the KEYLESS-GO Control unit.

Digital key in smartphone, function	Model 205 as of Model year 2019 with code 889 (KEYLESS-GO) with code 896 (Vehicle access and drive authorization via mobile phone) Model 205 as of Model year 2019 with code 893 (KEYLESS-GO) with code 896 (Vehicle access and drive authorization via mobile phone)	GF80.20-P-0010RFM
Electrical function diagram for Keyless Go	Model 205 as of Model year 2019 with code 889 (KEYLESS-GO) Model 253.99 with code 889 (KEYLESS-GO)	PE80.61-P-2050-97FBB
Function schematic for electric KEYLESS-GO engine start/stop	Model 205 as of Model year 2019 with code 893 (KEYLESS-GO) Model 253.99 with code 893 (KEYLESS-GO)	PE80.61-P-2052-97FBB
Overview of system components for theft protection and locking		GF80.00-P-9999RF