Brake pedal switch (Engine management system - Td5)

Brake pedal switch

The brake pedal switch is located above the pedal box assembly and activates when the brake pedal is operated. The ECM uses the signal from the brake pedal switch for the following functions: l To activate the brake lamps. l To limit fuelling during braking. l To cancel cruise control if operating.

The brake pedal switch consists of two component parts, one normally open switch and one normally closed switch.

Input/Output With the brake pedal in the off position the two switches will give opposite signals to the ECM. When the pedal is operated the signals exchange operating state.

With the brake pedal pressed the ECM receives the following: l 12 volts via pin 10 of the ECM connector C0658. l 0 volts via pin 16 of the ECM connector C0658.

With the brake pedal released the ECM receives the following: l 0 volts via pin 10 of the ECM connector C0658. l 12 volts via pin 16 of the ECM connector C0658.

The brake pedal switch can fail in the following ways: l Switch open circuit. l Short circuit to vehicle supply. l Short circuit to earth.

In the event of a brake pedal switch failure the ECM will disable cruise control.