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Home >> Volvo >> 1999 >> C70 2D Convertible, Standard >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Ignition And Control Systems - Design And Function (Convertible) >> Input Signals (B5234T3; B5254T; 1998) >> Knock sensor (KS)

Knock sensor (KS)

Fig 1: Identifying Knock Sensors (KS)
GLL118150Courtesy of VOLVO CARS OF NORTH AMERICA.

The function of the two knock sensors (KS) is to provide the engine control module (ECM) with signals to determine whether the engine is knocking.

The engine control module (ECM) uses the knock sensor (KS) and camshaft position (CMP) sensor signals to identify the cylinder in which knock is present.

The engine management system incorporates two knock sensor (KS), each of which consists of the following components: 

Engine knock produces vibrations which are transmitted through the block. The piezo-electric crystal reacts to these by transmitting a signal (a function of sound wave frequency and amplitude) to the engine control module (ECM).

The front knock sensor (KS) detects knocking in cylinders 1, 2 and 3. The rear knock sensor (KS) detects knocking in cylinders 4 and 5.

The knock sensors (KS) are mounted on the cylinder block.