ME engine speed signal, function - GF07.61-P-3017MIG

ENGINE 272.945 in MODEL 251.054/154 as of Model Year 2009/AEJ 08 

ENGINE 272.967 in MODEL 164.186 as of Model Year 2009/AEJ 08 MOPF 

ENGINE 272.967 in MODEL 251.056/065/156/165 as of Model Year 2009/AEJ 08 

ENGINE 273.923 in MODEL 164.871 as of Model Year 2009/AEJ 08 

ENGINE 273.963 in MODEL 164.172 as of Model Year 2009/AEJ 08 MOPF 

ENGINE 273.963 in MODEL 164.886, 251.072/172 as of Model Year 2009/AEJ 08 

Engine speed signal unction requirements, general 

• Circuit 87 M ON (engine control ON)
• Engine running

Engine speed signal, general 

Using the signal from the crankshaft Hall sensor (B70), the ME-SFI control unit (N3/10) generates the short-circuit-proof engine speed signal (TN) (for example, for mechanical testing and diagnosis), and sends it as a direct signal.

Engine speed signal function sequence 

A voltage pulse (AC voltage) is generated in the crankshaft Hall sensor by the stays on the increment wheel (perforated plate) for a turning crankshaft. Here each stay generates a voltage pulse. No voltage is generated as a result of the gap created by 2 missing stays.

The engine speed signal is a square wave signal with a constant duty cycle of 6 pulses per engine revolution (60° CKA (C  rank A  ngle)) and a maximum current of about 20 mA.

If the voltage pulse fails from the crankshaft Hall sensor, voltage pulses from the intake camshaft Hall sensors, on the left and right (B6/4, B6/5) are used instead (for limp-home mode) or used by the exhaust camshaft Hall sensors, on the left and right (B6/6, B6/7).

The engine speed signal can be read out at the data link connector (X11/4) using commercially available diagnostic units.

Fig 1: Intake Hall Sensor Voltage Waveform - Signal Assignment Engine 272

Courtesy of MERCEDES-BENZ USA

Signal assignment engine 272 

Fig 2: Intake Hall Sensor Voltage Waveform - Signal Assignment Engine 273

Courtesy of MERCEDES-BENZ USA

Signal assignment engine 273