All about Ford Mondeo

General information
Body electrical system / General information

Warning: Before carrying out any work on the electrical system, read through the precautions given in Safety first! at the beginning of this manual.

The electrical system is of 12-volt negative earth type. Power for the lights and all electrical accessories is supplied by a lead/acid battery which is charged by the alternator.

This Chapter covers repair and service procedures for the various electrical components not associated with the engine.

Information on the battery, ignition system, alternator, and starter motor can be found in Chapter 5.

All models are fitted with a drivers air bag, which is designed to prevent serious chest and head injuries to the driver during an accident. A similar bag for the front seat passenger is also available (see illustration).

1.3A Air bag system components
1.3A Air bag system components

1 Air bag module (drivers) 2 Clock spring
3 Diagnostic and sensor unit 4 Air bag indicator light 5 Air bag module (passengers)

The sensor and electronic unit for the air bag is located next to the steering column inside the vehicle, and contains a back-up capacitor, crash sensor, decelerometer, safety sensor, integrated circuit and microprocessor (see illustration).

1.3B Air bag sensor and electronic unit
1.3B Air bag sensor and electronic unit

1 Crash sensor
2 Safety sensor
3 Voltage back-up
4 Application Specific Integrated Circuit 5 Microprocessor

he air bag is inflated by a gas generator, which forces the bag out of the module cover in the centre of the steering wheel. A clock spring ensures that a good electrical connection is maintained with the air bag at all times - as the steering wheel is turned in each direction, the spring winds and unwinds.

All UK models are fitted with an alarm system incorporating a movement sensor and ignition immobiliser. On Saloon and Hatchback models, the alarm system horn is located on the left-hand side of the luggage compartment, but on Estate models, it is on the right-hand side.

Some models are fitted with a headlight levelling system, which is controlled by a knob on the facia. On position 0, the headlights are in their base position, and on position 5, the headlights are in their maximum inclined angle.

It should be noted that, when portions of the electrical system are serviced, the cable should be disconnected from the battery negative terminal, to prevent electrical shorts and fires.

Caution: When disconnecting the battery for work described in the following Sections, refer to Chapter 5, Section 1.

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