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Home >> Volvo >> 2012 >> C70 >> Repair and Diagnosis >> Engine Performance >> System >> Electronics - Design And Function - 2 Of 4 >> Engine Control Module (ECM) (B5244S4; 2006-2007) >> Design >> Ignition Switch
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Ignition Switch

Fig 1: Identifying Ignition Switch
GLL128852Courtesy of VOLVO CARS CORPORATION

The ignition switch powers certain functions in the engine control module (ECM) via fuses in the front integrated relay/fuse box and central electronic module (CEM). The ignition switch also supplies the engine control module (ECM) with signals such as:

"wake up" signal 

The ignition switch transmits a high signal to the engine control module (ECM) via the central electronic module (CEM) indicating that the ignition switch is in position I or II. The system prepares for start-up (for example by temporarily activating the fuel pump relay).

Start signal 

The ignition switch transmits a high signal to the engine control module (ECM) when the ignition switch is in position III.

The engine control module (ECM) activates the starter motor relay. The relay in turn activates the starter motor. See also: START 

The fuse in the front integrated relay/fuse box supplies current to the ignition switch.

The central electronic module (CEM) has diagnostics for the ignition switch.