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

Model 205, 253 

Function requirements, general 

• No overvoltage or undervoltage
• Terminal 15 ON

The electronic ignition lock control unit (N73) sends the status of circuit 15 via interior CAN (CAN B) to the front SAM control unit (N10/6).

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 

When the reverse gear (transmission 716) or gear range "R" (transmission 722, 724, 725) is engaged, the front SAM control unit activates the backup light actuation.

The "reverse gear engaged" status is defined as follows:

• Vehicles with transmission 716:

  Engaging the reverse gear is recorded by the manual transmission main shifter shaft position sensor (B79/3). The CDI control unit (N3/9) (diesel engine) or the ME-SFI [ME] control unit (N3/10) (gasoline engine) directly reads in the signals of the manual transmission main shifter shaft position sensor and sends the "Reverse gear engaged" signal via drive train CAN, powertrain control unit and chassis FlexRay to the electronic ignition lock control unit.

• Vehicles with transmission 722, 724, 725:

  The request to "Engage gear range R" is defined by the corresponding selector lever position. The fully integrated transmission control unit (Y3/8n4) sends the gear range over the drive train CAN (CAN C1), powertrain control unit (N127) and chassis FlexRay (Flex E) to the electronic ignition lock control unit.

The electronic ignition lock control unit uses the incoming information to generate the signal "Reverse gear engaged" that is independent of the transmission variant and sends it to the front SAM control unit via the interior CAN.

The front SAM control unit sends the "Switch on backup lights" request to the rear SAM control unit (N10/8) via interior CAN. The rear SAM control unit receives this signal and actuates the following components:

• Left rear lamp unit (E3) (model 205.0/1):
  • Left backup lamp (E3e3)
• Inner left rear lamp unit (E3/1) (model 205.2, 253):
  • Left backup lamp (E3/1e3)
• Right rear lamp unit (E4) (model 205.0/1):
  • Right backup lamp (E4e3)
• Inner right rear lamp unit (E4/1) (model 205.2, 253):
  • Right backup lamp (E4/1e3)

On vehicles with CODE 550 (Trailer hitch), the front SAM control unit sends the "Switch on backup lights" request via interior CAN to the trailer recognition control unit (N28/1), which actuates the backup lights on the trailer via the trailer socket (X58).

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