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

ENGINE 275.953 in MODEL 216.376, 221.176 as of Model Year 09/AEJ 08 

ENGINE 275.982 in MODEL 216.379, 221.179 as of Model Year 09/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 (L5), the ME-SFI control unit (N3/10) generates the short-circuit-proof engine speed signal (TN) (e.g. for mechanical testing and diagnosis) and sends it as a direct signal.

Engine speed signal function sequence 

When the crankshaft is turning, a voltage signal (AC voltage) is generated in the crankshaft position sensor by the teeth on the increment wheel (perforated plate). 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 3 pulses per revolution (120° CKA (CranK Angle)) and maximum current about 20 mA.

If the voltage signal from the crankshaft position sensor is missing, the voltage signal from the crankshaft Hall sensor of the RH cylinder bank (B6/3) is used instead (in limp-home mode)

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

Signal assignment 

Fig 1: ME Engine Speed Signal Function Diagram

Courtesy of MERCEDES-BENZ USA