Brake Signal: Description and Operation

PURPOSE
The brake switch signal comes from the stoplight circuit and signals the engine control module (ECM) when the brakes are applied.

OPERATION
The ECM monitors the stoplight circuit through ECM terminal 2L. When the brake pedal is released, the voltage in the stoplight circuit is zero. When the brake is applied, voltage in the circuit goes to approximate battery voltage. The ECM interprets the voltage signal as a "brake applied and/or deceleration condition".