Circuit Description

This signal is used to detect that the brakes have been applied. The STP signal voltage is the same as the one supplied to the stop lights.

The STP signal is used mainly to control the fuel cut-off engine speed (The fuel cut-off engine speed is reduced slightly when the vehicle is braking.).

The MIL (Malfunction Indicator Lamp) is used to indicate the ECM detection of vehicle malfunctions.

By turning the ignition switch to ON, the power is supplied to the MIL circuit, and the ECM provides the circuit ground that illuminates the MIL.

Operation of the MIL should be checked visually:

When the ignition switch is first turned to ON, the MIL should be illuminated. If it is always OFF or ON, use the hand-held tester or OBD II scan tool and follow the procedure below to determine cause of the problem.