Electronic accelerator pedal emergency running mode, function - GF30.20-P-4026AMG

ENGINE 156.980 in MODEL 164, 251 up to Model Year 8 

ENGINE 156.982 in MODEL 209 

ENGINE 156.983 in MODEL 211, 219 

ENGINE 156.984 in MODEL 216, 221 up to Model Year 8 

The task of the electronic accelerator emergency mode consists in ensuring that the vehicle can continue to be driven safely even in case of faults in the electronic accelerator system (EA).

Accelerator pedal sensor emergency running 

If a Hall sensor fails, the system switches over to the second Hall sensor. Throttle valve openings are limited to about 60% of the maximum opening. Furthermore the speed at which the throttle valve opens is dynamically limited (throttle valve opens with a delay).

If the plausibility check is negative or if both Hall sensors fail, only idle speed is then still controlled.

Emergency mode in the event of failure of the throttle valve potentiometer 

If one potentiometer fails, the system switches over to the second, intact potentiometer. The air mass value of the sequential multiport fuel injection system is used as an additional comparative parameter. If both potentiometers of a throttle valve actuator are defective then every two throttle valve actuators will be de-energized and the throttle valve brought into the limp-home position of a 4° opening angle by the spring capsules.

Emergency mode in the event of failure of the throttle valve actuator 

The throttle valve actuators are switched to a de-energized state and the throttle valve is brought to the limp-home position of a 4° opening angle by the spring capsules.

Engine speed control with throttle valve in emergency mode position 

In the idle speed range, engine speed is regulated to approx. 1200 RPM up to 1400 RPM by shutting off and switching on cylinders on fuel side.

While driving, depending on the engine load, engine speed is controlled to about 1800 RPM by switching the cylinders on and off on the fuel side. In doing so, the maximum engine speed is determined by the limp-home position of the throttle valves.

Limp-home is recognizable from a significantly surging engine running characteristic.

Faults detected by the accelerator pedal sensor and throttle valve actuators are stored in the fault memory and can be read out and deleted with the STAR DIAGNOSIS.

The input signals for switching the cylinder on and off (fuel injection valves) are:

• Engine speed
• Brake detection (via the ESP control unit)
• Drive position recognition (via the electric controller unit (VGS))

If the brake pedal is operated, this always means idle speed input.

	Component description for fuel injection valves	Y62y1-Y62y8	GF07.03-P-6010AMG
	Component description for the crankshaft Hall sensor	B70	GF07.04-P-6220AMG
	Component description for the hot film mass air flow sensor	B2/6, B2/7	GF07.07-P-6000AMG
	Component description for the ME-SFI [ME] control unit	N3/10	GF07.61-P-6000AMG
	Component description for the accelerator pedal sensor	B37	GF30.20-P-2010AMG
	Component description for the throttle valve actuator	M16/3, M16/4	GF30.20-P-2020AMG