Thermal Management, Function - GF07.10-P-1012KJ

ENGINE 281.910 in MODEL 453.0/3/4 

Function requirements for thermal management, general points 

• Circuit 87 (Engine management ON)
• Engine runs

Thermal management, general 

The coolant temperature of the engine is regulated with the thermal management controlled by the ME-SFI [ME] control unit (N3/10). The following advantages arise from this:

• Rapid reaching of the optimal operating temperature
• Reduction of the exhaust emissions
• Fuel savings
• Improved heating comfort

Thermal management controlling is dependent on the following sensors and signals:

• Coolant temperature sensor (B11/4)
• Intake air temperature sensor (B17) (Charge air temperature upstream of throttle valve)
• Charge air temperature sensor (B17/8) (Charge air temperature downstream of charge air cooler)
• Pressure sensor downstream of throttle valve (B28/7), engine load
• Accelerator pedal sensor (B37), accelerator pedal actuation
• Crankshaft position sensor (L5), engine speed
• DKG control unit (N15/13) (for code 429 (twinamic)), status of transmission oil temperature via drive train CAN (CAN C)
• Climate control control unit (N22/1) (for code I01 (AAC)), status of A/C via the interior CAN (CAN B)
• Electronic Stability Program control unit (N30/4), wheel speed via the interior CAN

Function sequence for thermal management 

The thermal management is described in the following points:

• Function sequence for overheating protection 
• Function sequence for fan control 
• Function sequence for controlling the charge air cooler circulation pump 

Function sequence for overheating protection 

In a case of thermal overload the overheating protection protects the catalytic converters against engine damage and overheating damage.

The following measures are taken for overheating protection:

• Characteristics map dependent ignition angle setting in the direction "retard", dependent on the engine load and rotational speed, coolant temperature and the charge air temperature
• Reduced opening of the throttle valve actuator (M16/6), dependent on the engine load and speed
• Shortening of the injection period of cylinder 1 injection valve (Y62/1) to cylinder 3 injection valve (Y62/3) according to the low air volume

If the coolant temperature is too high, the coolant temperature warning lamp (A1e54) in the instrument cluster (A1) is actuated. For vehicles with code K36 (IC with a colored 8.9 cm (3.5") display) a warning message is also displayed in the multifunction display (A1p13) of the IC. To do this, the ME-SFI [ME] control unit transmits the appropriate signal over the interior CAN to the instrument cluster.

Function sequence for fan control 

Fan motor (M4/7) on radiator 

For vehicles with code I77 (Manual A/C) or code I01 (AAC) the fan motor (M4/7) is actuated by the ME-SFI [ME] control unit over the fan solenoid switch, internal combustion engine cooling ICE (K32). For vehicles with code I78(Heating system) the fan motor (M4/7) is actuated by the ME-SFI [ME] control unit over the fan relay (F1k1) in the power supply fuse and relay module (F1). For controlling the ME-SFI [ME] control unit. amongst other things, uses the signal of the coolant temperature sensor.

Fan (M4/4) in engine compartment 

The fan (M4/4) in the engine compartment is actuated by the ME-SFI [ME] control unit over the fan relay (F11k2) in the internal combustion engine fuse and relay module (F11). The fan in the engine compartment is used for direct air cooling of the engine and, in particular, also the charge air system with ATL.

Delayed fan switch off 

After "ignition OFF", the fan motor continues to run for up to some minutes if the coolant temperature or engine oil temperature is above the specified maximum value. If the battery voltage drops down a lot, the delayed fan switch off is suppressed.

Function sequence for controlling the charge air cooler circulation pump 

Vehicles with engine 281.910 are fitted with a charge air cooler (water charge air cooler) integrated in the charge air distributor, which cools hot charge air from the ATL by means of the flowing through coolant. To do this the charge air cooler circulation pump (M44) delivers the coolant from the front cooler to the charge air cooler in the engine. As required the ME-SFI [ME] control unit switches the charge air cooler circulation pump on or off. As a reference for controlling the charge air cooler circulation pump, the ME-SFI [ME] control unit, amongst other things, reads in the signals of the intake air temperature sensor (charge air temperature upstream of throttle valve) and the charge air temperature sensor (charge air temperature downstream of charge air cooler). Through controlling the charge air temperature it is possible, amongst other things, to reduce the exhaust emissions and the efficiency of the engine is increased.

Model 453.062/362/462 BRABUS 

Vehicles with code ICBA (BRABUS) are fitted with a powerful charge air cooler circulation pump, controlled by the ME-SFI [ME] control unit over pulse width modulation (PWM), whereby this can be continuously rpm regulated.

	Electrical function schematic for heat management		PE07.10-P-2712-97BBA
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