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

ENGINE 272.911 in MODEL 204.0 up to Model Year 08/AEJ 07 

ENGINE 272.921 in MODEL 204.0/2 up to Model Year 08/AEJ 07 

ENGINE 272.947 in MODEL 204.0/2 up to Model Year 08/AEJ 07 

ENGINE 272.948 in MODEL 204.0 up to Model Year 08/AEJ 07 

ENGINE 272.961 in MODEL 204.0/2 up to Model Year 08/AEJ 07 

ENGINE 272.971 in MODEL 204.0 up to Model Year 08/AEJ 07 

The task of the electronic accelerator emergency mode consists in ensuring that the car can be continued to be driven safely even in case of any faults in the electronic accelerator system (EA). Limp-home is recognizable from a significantly surging engine running characteristic.

Accelerator pedal sensor limp-home mode (B37) 

If a Hall sensor fails, the system switches over to the second Hall sensor. The throttle valve opening is limited to about 60% of the maximum opening. In addition, the speed at the 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.

Limp-home mode if throttle valve potentiometer fails 

If one potentiometer fails, the other potentiometer is used. The air flow mass serves as a second parameter for comparative purposes. If both potentiometers are faulty, the spring capsule brings the throttle valve into the limp-home position of about 10° opening angle.

Limp-home mode in case of failure of the throttle valve actuator motor (M16/6m1) 

The throttle valve positioner is de-energized and the throttle valve is brought into the limp-home position of about 10° opening angle by the spring capsule.

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.

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

In driving mode, engine speed is limited to about 1800 rpm (depending on engine load) by switching the cylinders on/off on the fuel side. In doing so, the maximum engine speed is determined by the throttle valve emergency mode position.

The input signals for switching on/off the cylinders (injection valves (Y62)) are:

• Engine speed
• Brake actuation (from the Electronic Stability Program control unit (N30/4))
• Gear ranges (through the electronic selector lever module control unit (N15/5)) (for automatic transmission 722.9)

Faults detected in the accelerator pedal sensor and throttle valve positioner are stored in the fault memory and can be read out and deleted with the DAS.

	Electrical function schematic for electronic accelerator pedal limp-home mode		PE30.20-P-2051-99FAB
	Fuel injection valves, component description	Y62/1-Y62/6	GF07.03-P-6010CY
	Crankshaft Hall sensor component description	B70	GF07.04-P-6221CY
	Hot film mass air flow sensor, component description	B2/5, B2/5b1	GF07.07-P-6000CY
	ME-SFI [ME] control unit, component description	N3/10	GF07.61-P-6000CY
	Component description for accelerator pedal sensor	B37	GF30.20-P-2011CY
	Component description for the throttle valve actuator	M16/6	GF30.20-P-2021CY