(Component Description For Exhaust Aftertreatment Control Unit - GF14.40-P-3030OGW)

Engine 642.8 in model 213 

up to model year 2021 

with code U77 (Diesel Emission control BLUETEC (SCR)) 

Engine 642.8 in model 238 

up to model year 2021 

Courtesy of MERCEDES-BENZ USA

Vehicle view of model 213.0 

Location 

The AdBlue® control unit is located in the trunk at the lower right.

Tasks 

The AdBlue® control unit controls the following tasks based on a characteristics map:

• AdBlue® delivery
• AdBlue® injection
• Antifreeze protection and AdBlue® recirculation

Input and output signals 

The following input signals are evaluated by the AdBlue® control unit and the respective output signal is issued:

• Direct input signals 
• Direct output signals 
• CAN input signals 
• CAN output signals 

Direct input signals 

• Circuit 31
• Circuit 30, over AdBlue® circuit 87 relay (K40/5kV)
• Signal for AdBlue® fill level sensor (A103/1 b5)
• AdBlue® container temperature sensor signal (A103/1b1)
• Recording of power consumption for diagnosis of the AdBlue® delivery pump (A103m1)

Direct output signals 

• Supply of AdBlue® delivery pump
• Supply and actuation of the AdBlue® extraction pump (A103/2m2)
• Pulse width modulated signal for actuation of the AdBlue® delivery pump
• Pulse width modulated signal for actuation of the AdBlue® metering valve (Y129)
• Power supply for the AdBlue® container heating element (A103/1r1)
• Power supply for AdBlue® pressure line heating element (R7/1)

CAN input signals 

CDI control unit (N3/9) 

• Request for reduction agent injection
• Specification of the reduction agent quantity to be injected
• Specification for the run-on time of the AdBlue® control unit
• Diagnosis request

CAN output signals 

CDI control unit 

• Reduction agent quantity to be injected for NO_x reduction
• Reduction agent quantity injected for cooling the AdBlue® metering valve
• Fill level status in the AdBlue® container
• Requested diagnostic data

AdBlue® delivery 

• Feed to AdBlue® delivery pump to obtain the operating current consumption as a basis for diagnosis of the AdBlue® delivery pump
• Actuation of AdBlue® delivery pump, to generate a pressure of 5 bar before and during the injection of reducing agent for nitrogen oxide (NO_x ) reduction. The delivery pressure is adjustable by the control unit software and can be different according to the variant.
• Actuation of AdBlue® delivery pump, to generate pressure of 5 bar before and during reduction agent injection for cooling AdBlue® metering valve
• Actuation of the AdBlue® metering valve for ventilation of the AdBlue® pressure line when filling the AdBlue® pressure line

AdBlue® injection 

• Actuation of the AdBlue® metering valve during the reduction agent injection for NOx reduction

Antifreeze protection and AdBlue® recirculation 

• After "circuit 15 ON", the pump is given an initial run (warm-up) if the weather is cold. The pump flow serves to remove the friction in the case of cold, so that the desired pressure can be made available as soon as possible after the pressure request.
• Actuation of AdBlue® tank heating element to liquefy AdBlue® reduction agent, which freezes as of approx. -10°°C in AdBlue® tank
• Actuation of AdBlue® delivery module heating element (A103/2) and AdBlue® pressure line heating element to ensure flowability of AdBlue® reduction agent, which freezes as of approx. -10°°C, in AdBlue delivery module® and in AdBlue® pressure line to AdBlue® metering valve
• Actuation of the AdBlue® extraction pump for return delivery of the AdBlue® reduction agent in the AdBlue® pressure line in the AdBlue® tank during power-down of the AdBlue® control unit after "terminal 15 OFF"
• The AdBlue® metering valve can be actuated without the float needle being opened. This serves to heating of the valve.

The duration of the return flow of the AdBlue® reduction agent and the duration of the pressure line filling dependent on the length of the AdBlue® pressure line.

The quantity of reduction agent injected by AdBlue® the metering valve is sent by the AdBlue® control unit via the drive train sensor CAN (CAN I) to the CDI control unit. This is taken into account in the subsequent computation of the necessary quantity of reduction agent by the CDI control unit.

	Wiring diagram for AdBlue® control unit	Engine 642.8 in model 213 up to model year 2021 with code U77 (Diesel Emission control BLUFTFC (SCR))	PF14.40-P-2101-97DBA
		Engine 642.8 in model 238 up to model year 2021	PF14.40-P-2101-97DCA