Brake Switch Outputs (Engine management system - EDC)

Brake Switch Outputs

In the event of a brake switch failure any of the following symptoms may be observed: l Cruise control will be inactive. l Increased fuel consumption.

Clutch Switch

The clutch switch is a Hall effect device and is located on the pedal box assembly. The clutch switch is activated when the clutch pedal is operated. The ECM uses the signal from the clutch switch for the following functions: l To provide surge damping during gear changes. l To inhibit/ cancel cruise control if the clutch pedal is pressed.

Surge damping stops engine speed rising dramatically during gear changes. Surge damping assists driveability in the following ways: l Smoother gear changes. l Greater exhaust gas emission control. l Improved fuel consumption.

The clutch switch receives a 12 volts reference voltage from the ECM. With the clutch pedal in the rest position the switch is connected to earth. When the clutch pedal is pressed the ECM receives a 12 volt signal.

In the event of a clutch pedal switch failure any of the following symptoms may be observed: l Surge damping will be inactive l Cruise control will be inactive

Main Relay

The main relay is located in the E-box in the engine compartment. The relay controls the voltage supplies to the main peripheral components of the system under the control of the ECM. The ECM has a feed which allows it to become active when it receives an input from the ignition switch position II (ignition on). The ECM will then energise the main relay.

The main relay is a standard normally open 4 pin relay.

The main relay contact supplies battery voltage to the following components: l ECM. l MAF/ IAT sensor. l CMP sensor. l Fuel pressure regulator. l EGR modulator. l Glow plug relay.