Backup lamp actuation, function - GF82.10-P-3011CA

MODEL 207.3/4 up to model year 2014 

Function requirements, general 

• No overvoltage or undervoltage (operating voltage range U ≥ 7 ≤ 17.5 V)
• Circuit 15 ON

The electronic ignition lock control unit (N73) transmits the circuit 15 status to the front SAM control unit with fuse and relay module (N10/1) over the interior CAN (CAN B).

Backup light actuation, general 

The backup light actuation enables the traffic lane to the rear of the vehicle to be illuminated when backing up.

Function sequence for backup light actuation 

Vehicles with transmission 711, 716 (manual transmission):

Engagement of the reverse gear is defined using the status of the backup lamp switch (S16/2), which is read in directly by the front SAM control unit.

Vehicles with transmission 722 (automatic transmission):

The request to "Engage gear range R" is defined by the corresponding selector lever position.

The electronic selector lever module control unit (N15/5) transmits the selector lever position over the drive train CAN (CAN C), CDI control unit (N3/9) (with diesel engine) or ME-SFI [ME] control unit (N3/10) (with gasoline engine) and the chassis CAN (CAN E) to the front SAM control unit.

Two microprocessors are installed in the front SAM control unit, one for control of basic functions, e.g. the exterior lights, and the second for control of the central gateway functions. Both processors communicate with each other internally via interior CAN. The microprocessor for control of the central gateway functions uses the incoming information to generate the "Reverse gear engaged" signal irrespective of the transmission variant, and sends this over interior CAN to the rear SAM control unit with fuse and relay module (N10/2) and, on vehicles with code (550) Trailer hitch, also to the trailer recognition control unit (N28/1).

The rear SAM control unit receives the "Reverse gear engaged" signal and actuates the left backup lamp (E3/1e3) in the left rear inner lamp unit (E3/1) and the right backup lamp (E4/1e3) in the right rear inner lamp unit (E4/1).

The trailer recognition control unit receives the "Reverse gear engaged" signal, and actuates the backup lamp on the trailer over the trailer socket (X58).

To prevent any brief illumination of the backup lamps in vehicles with transmission 722 when changing from gear range "P" to "D" via "R", the request from the front SAM control unit is sent with a delay of t = 500 ms.

	Electrical function schematic for backup light actuation		PE82.10-P-2058-97EAA
	Overview of exterior lights system components		GF82.10-P-9998CA