Engine start/stop, function - GF80.61-P-3012GM

MODEL 164.1 as of model year 2009 with CODE 889 (Keyless Go)

MODEL 164.8, 251.0/1 as of model year 2009 with CODE 889 (Keyless Go)

Function requirements, general

The transmitter key (A81) is located in the vehicle interior

Engine start/stop, general

The engine start/stop function allows to start and stop the engine.

The engine start/stop function encompasses the following subfunctions:

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

Function sequence for interrogation of transmitter key

To ensure reliable and safe function of the start/stop function, it is necessary to determine the position of the transmitter key and authorize it. The KEYLESS-GO control unit (N69/5) starts checking 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 liftgate is not closed.
When the engine starts

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

The KEYLESS-GO control unit transmits a coded request to the transmitter key via the following antennas:

Keyless Go cockpit antenna (A2/60)
interior KEYLESS-GO antenna (A2/61)
KEYLESS-GO trunk antenna (A2/35) (on MODEL 164.8, 251.0/1 up to 31.7.10 and MODEL 164.1)

The transmitter key decodes these queries and transmits the corresponding coded responses to the KEYLESS-GO control unit via the roof antenna module (A2/93). The KEYLESS-GO control unit receives the responses from the transmitter key and evaluates them. If the evaluation is positive, the KEYLESS-GO control unit authorizes the transmitter key and transmits the access authorization code to the EZS control unit (N73) via the interior CAN.

Additional function requirements for starting engine

Transmission in position "P" or "N"
Brake pedal operated

The intelligent servo module for DIRECT SELECT (A80) transmits the information on the current transmission selector lever position over the engine compartment CAN (CAN C), central gateway control unit (N93) and the interior CAN to the KEYLESS-GO control unit.

The ESP control unit (N47-5) (except MODEL 164.195) or regenerative braking system control unit (N30/6) (on MODEL 164.195) transmits the status of the service brake to the KEYLESS-GO control unit via engine compartment CAN, central gateway control unit and interior CAN.

Function sequence for starting engine

Starting the engine is requested by pressing the KEYLESS-GO start/stop button (S2/3).

Detailed information on the signal path is given in the chapter "Checking transmitter key".

If the access authorization code is valid, the EZS control unit transmits the circuit status of circuit 50 via the engine compartment CAN to the CDI control unit (N3/9) (on diesel engine) or ME-SFI control unit (N3/10) (on gasoline engine) and then engine is started.

Activating circuit:

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. If the driver door is closed, circuit 15C remains active for t = 30 min.

Function sequence for display of messages

The KEYLESS-GO control unit transmits the request to display error messages to the instrument cluster via the interior CAN.

The following situations lead to the output of messages:

After unsuccessful key search, the instrument cluster outputs the message "Key not recognized".
If no transmitter key is recognized in the vehicle interior after five activations of the KEYLESS-GO start/stop button, the message "Please insert key" is displayed on the instrument cluster. The start attempt is not started. The status of the circuit remains unchanged.
If a transmitter key is not recognized in the vehicle interior when circuit 15C is ON, the instrument cluster outputs message "Key not recognized" in red lettering.
If, when the engine is running, a transmitter key is not recognized in the vehicle interior (e.g. someone gets out the car with the key), the instrument cluster outputs the message "Key not recognized".
If, during a starting attempt, the transmission is not in position "P" or "N", a corresponding message appears in the instrument cluster.

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 EZS control unit senses this request and transmits the status "KEYLESS-GO 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 "Circuit 15 OFF" to the EZS control unit via the interior CAN. The EZS control unit transmits the circuit 15 ON status to the CDI control unit (with diesel engine) or the ME-SFI control unit (with gasoline engine).

The CDI control unit (on diesel engine) or ME-SFI control unit (on gasoline engine) then shuts off the engine depending on the vehicle speed:

Speed v = 3 km/h: Engine switched off immediately.
Speed v > 3 km/h: Engine is switched off after pressing (t > 3 s) KEYLESS-GO start/stop button.

The instrument cluster transmits the vehicle speed to the KEYLESS-GO control unit via the interior CAN.

Function schematic for electric KEYLESS-GO engine start/stop	MODEL 164.1 as of model year 2009 with CODE 889 (Keyless Go) MODEL 164.8 as of model year 2009 with CODE 889 (Keyless Go)	PE80.61-P-2052-97MAA
	MODEL 251.0/1 as of model year 2009 with CODE 889 (Keyless Go)	PE80.61-P-2052-97RAA
Survey of Keyless Go system components, component description		GF80.61-P-9997GM