Brake light switch

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Fig 1: Identifying Brake Light Switch

Courtesy of VOLVO CARS OF NORTH AMERICA.

The purpose of the brake light switch is to provide the engine control module (ECM) with information indicating whether the brake pedal is depressed.

A signal is transmitted to the engine control module (ECM) when the brake pedal is pressed. The engine control module (ECM) disengages the cruise control (if activated). The brake pedal sensor also disengages cruise control. For further information, see VIDA Design and Function, Brake system, design.

The brake light switch is supplied with power from the ignition switch (terminal 30). When the brake pedal is depressed the switch closes and a high signal (12 V) is transmitted to the engine control module (ECM).

The engine control module (ECM) can diagnose the brake light switch. The status of the switch (pressed or not) can be read using VIDA.

The brake light switch is on the pedal box by the brake pedal.