Backup Lamp Actuation, Function - GF82.10-P-3011RDM

Model 172.4 as of model year 2017 

Function requirements, general 

• No overvoltage or undervoltage
• Terminal 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 signals to other road users the intention of backing up and illuminates the road behind the vehicle during reverse travel.

Function sequence for backup light actuation 

When the reverse gear (with transmission 711 or 716) or gear range "R" (with transmission 725) is engaged, the backup light actuation is activated.

Vehicles with transmission 711 or 716 (manual transmission): 

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

Vehicles with transmission 725 (automatic transmission): 

The status of the reverse gear is sent by the fully integrated transmission control unit (Y3/8n4) over the drive train CAN (CAN C), CDI control unit (N3/9) or the ME-SFI [ME] control unit (N3/10) and chassis CAN 1 (CAN E1) to the front SAM control unit. The front SAM control unit sends the "Reverse gear engaged" signal over the interior CAN to the rear SAM control unit with fuse and relay module (N10/2).

The rear SAM control unit receives this signal and actuates the left backup lamp (E3e3) in the left rear lamp unit (E3) and the right backup lamp (E4e3) in the right rear lamp unit (E4).

To avoid any brief lighting up of the backup lights when shifting from the "P" gear range to "D" via "R", the request is sent by the front SAM control unit with a delay of t = 500 ms.

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