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Home >> Mercedes Benz >> 2019 >> A220 Base >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (Frame, Trailer Operation -- 118 Chassis) >> Testing & Repair >> Remove/Install Trailer Recognition Control Unit - AR31.19-P-1300MFA

Remove/Install Trailer Recognition Control Unit - AR31.19-P-1300MFA

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Model 118.3/6, 177.0/1, 243.7, 247 with code 550 (Trailer coupling) 

Model 243.7 with code 554 (Preinstallation for trailer hitch) 

Fig 1: Trailer Recognition Control Unit Components Location - Model 118.3 With Code 550 (Shown On Model 177.0)
G16049841Courtesy of MERCEDES-BENZ USA

Shown on model 177.0 with code 550 (Trailer hitch) 

WARNING Risk of injury  caused by fingers being jammed or pinched when removing, installing or aligning hoods, doors, trunk lid/rear-end door or sliding roof. No parts of the body or limbs should be within the operating area when the components are moving. AS00.00-Z-0011-01A
Topical note  Information on preventing damage to electronic components due to electrostatic discharge   AH54.00-P-0001-01A
  Notes on HANDS-FREE ACCESS   AH80.61-P-0001-01A
REMOVINGINSTALLING Remove/install     
1 Switch off ignition and store transmitter key outside of transmitter range (min. 2 m).    
2 Remove trim in trunk on right side. Model 247.6 with code 550 (Trailer coupling) AR68.30-P-4801MFX
    Model 177.0 with code 550 (Trailer coupling) AR68.30-P-4800MFA
    Model 118.3, 177.1 with code 550 (Trailer coupling) AR68.30-P-4800MFV
    Model 243.7, 247.0/7 with code 550 (Trailer coupling)
Model 243.7 with code 554 (Preinstallation for trailer hitch)
AR68.30-P-4800MFB
    Model 118.6 with code 550 (Trailer coupling) AR68.30-P-4800MFD
3 Release and disconnect electrical connectors (1). IMPORTANT The number of electrical connectors (1) varies depending on the vehicle equipment.  
4 Remove nut (2) and take off trailer recognition control unit (N28/1).    
5 Install in the reverse order.    
6 Perform commissioning of trailer recognition control unit (N28/1). When replacing trailer recognition control unit (N28/1).  
REFER TO SELF-DIAGNOSTIC SYSTEMS     AD00.00-P-2000-06MFA
INSPECT Check     
7 Carry out function check of electrically unlocked trailer coupling. Model 118.3/6, 177.0/1, 243.7, 247 with code 550 (Trailer coupling) AR31.19-P-1451MFA 
8 Perform function check of light signals on trailer socket. IMPORTANT Aid of helper required.