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

Engine 656.9 in model 213, 238, 257 

up to model year 2021 

Engine 656.9 in model 222 

Shown model 222.0 

Courtesy of MERCEDES-BENZ USA

Location 

The AdBlue® control unit is located on the right in the trunk behind the trim.

Task 

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

• AdBlue® delivery
• Fuel injection
• Antifreeze protection and 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, via circuit 87 for the AdBlue® relay
• Terminal 15
• AdBlue® temperature sensor signal (A103b1)
• AdBlue® fill level sensor signal (A103b2)
• AdBlue® concentration sensor signal (A103b3)
• AdBlue® pressure sensor signal (A103b4)

Direct output signals 

• AdBlue® pump (A103m1) power supply
• Pulse width modulated signal for actuation of AdBlue® pump
• Pulse width modulated signal for actuation of the AdBlue® metering valve (Y129)
• Voltage supply for AdBlue® heating element (A103r1)
• Power supply for AdBlue® pressure line heating element (R7/1)

CAN input signals 

The AdBlue® control unit reads in the following signals from the CDI control unit (N3/9) via the drive train sensor CAN (CAN I):

• 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 

The AdBlue® control unit transmits the following signals to the CDI control unit via drive train sensor CAN:

• 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 

• AdBlue® pump feed line to achieve the operating current consumption as the basis for AdBlue® pump diagnosis.
• Actuation of the AdBlue® pump to generate a pressure of 5 bar before and during reduction agent injection 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 the AdBlue® pump to generate a pressure of 5 bar before and during reduction agent injection for cooling the AdBlue® metering valve.
• Actuation of the AdBlue® metering valve to ventilate the AdBlue® pressure line during the AdBlue® pressure line filling process.

Fuel injection 

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

Antifreeze protection and 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 the AdBlue® tank heating element to liquefy the AdBlue® reduction agent, which freezes as of approx. -10°C, in the AdBlue® tank.
• Actuation of the AdBlue® heating element and the AdBlue® pressure line heating element to ensure the flowability of the AdBlue® reduction agent, which is frozen as of approx. -10°C, in the AdBlue pump module® (A103) and the AdBlue® pressure line to the AdBlue® metering valve.
• Actuation of the AdBlue® pump to return the AdBlue® reduction agent contained in the AdBlue® pressure line to the AdBlue® tank during AdBlue® control unit power-down after "circuit 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 the AdBlue® metering valve is sent by the AdBlue® control unit via the drive train sensor CAN 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 656.9 in model 213 up to model year 2021	PE14.40-P-2101-97DBB
		Engine 656.9 in model 222	PE14.40-P-2101-97SEB
		Engine 656.9 in model 238 up to model year 2021	PE14.40-P-2101-97DCB
	Wiring diagram for AdBlue® control unit	Engine 656.9 in model 257 up to model year 2021	PE49.20-P-2103-97XBA