General information and precautions

Starting and charging systems / General information and precautions

General information
The engine electrical system consists mainly of the charging and starting systems.

Because of their engine-related functions, these components are covered separately from the body electrical devices such as the lights, instruments, etc (which are covered in Chapter 12). Refer to Part B of Chapter 5 for information on the ignition system.

The electrical system is of the 12-volt negative earth type.

The starter motor is of the pre-engaged type incorporating an integral solenoid. On starting, the solenoid moves the drive pinion into engagement with the flywheel ring gear before the starter motor is energised. Once the engine has started, a one-way clutch prevents the motor armature being driven by the engine until the pinion disengages from the flywheel.

Precautions
Further details of the various systems are given in the relevant Sections of this Chapter.

The battery may be of the low maintenance or ‘maintenance-free’ (sealed for life) type and is charged by the alternator, which is beltdriven from the crankshaft pulley.

While some repair procedures are given, the usual course of action is to renew the component concerned. The owner whose interest extends beyond mere component renewal should obtain a copy of the ‘Automobile Electrical & Electronic Systems Manual’, available from the publishers of this manual.

It is necessary to take extra care when working on the electrical system to avoid damage to semi-conductor devices (diodes, transistors and integrated circuits), and to avoid the risk of personal injury. In addition to the precautions given in Safety first!’ at the beginning of this manual, observe the following when working on the system: Always remove rings, watches, etc before working on the electrical system. Even with the battery disconnected, capacitive discharge could occur if a component’s live terminal is earthed trough a metal object This could cause a shock or nasty bum.

Do not reverse the battev connections.

Components such as the alternator, electronic control units, or any other components having semiconductor circuitry could & irreparably damaged.

If the engine is being started using jump leads and a slave battery, connect the batteries positive-to-positive and negativeto- negative (see ‘Booster battery (jump) starting’). This also applies when connecting a battety charger.

Never disconnect the battery terminals, the alternator, any electrical wiring or any test instruments when the engine is running.

Do not run the alternator with its output open circuit disconnected.

Never ‘test’ for alternator output by ‘flashing’ the output lead to earth.

Never use an ohmmeter or continuity tester of the type incorporating a handcranked generator for circuit or continuity testing.

Always ensure that the battery negative lead is disconnected when working on the electrical system.

Before using electric-arc welding equipment on the car, disconnect the battery, alternator and components such as the engine management system electronic control unit to protect them from the risk of damage.

Certain radio/cassette units fitted as standard equipment by VW are equipped with a built-in security code to deter thieves.

Refer to ´Radio/cassette unit anti- theft system precaution’ in the Reference section of this manual for further information.