The charging system consists of an alternator containing a rectifier pack and regulator to maintain a constant direct (dc) voltage in the system. The alternator is belt driven from the crankshaft and is cooled by a fan mounted behind the pulley. The alternator has a fixed coil wound stator in which a field coil rotor rotates. Slip rings conduct current to and from the field coils via 2 carbon brushes. The regulator senses output voltage and controls this to approximately 14 volts.
Operation - Starting
With the ignition switch in position 'II' (C0094-1), the Engine Control Module (C0158-29) provides a feed to the glow plug relay coil (C0215-4) on a green/blue wire. This feed energises the glow plug relay, and enables a battery feed from fusible link 1 (C0622-1) to flow across the relay switch (C0215-1 & C0215-3). The glow plug relay can now supply a feed to all four glow plugs on a yellow/black wire.
NOTE: The Td5 engine only has glow plugs in cylinders 1, 2, 3, and 4.
Glow plug pre-heat and post-heat times are determined by engine coolant temperature. See Engine Management.
When the ignition switch is turned to the 'crank' position, (C0090-1), current flows from the switch to the starter relay coil (C0151-4) on a white/red wire. The earth path for the relay (C0151-6) is controlled by the alarm ECU (C0057-10) on a black/orange wire. See Anti-theft Alarm.
With the starter relay energised, a battery feed from fusible link 5 of the passenger compartment fuse box (C0570-2) can flow across the relay switch (C0151-2 & C0151-8) to the starter motor (C0179-1) on a brown/red wire. This feed energises the starter solenoid, and allows a feed from the positive battery terminal to power the start motor (C0178-1). The starter motor is earthed via its fixings.
Operation - Charging
The battery positive terminal provides a feed to fusible link 1 and fusible link 5 of the engine compartment fuse box (C0632-1) on a brown wire. Both are connected in parallel.
Fusible link 5 (C0570-2) provides a feed to both the starter relay (C0151-2) and the ignition switch (C0028-1) on brown/white wires. With the ignition switch in position 'II' (C0094-1), current flows to fuse 6 and fuse 7 of the passenger compartment fuse box (C0580-9) on a white wire. Fuse 6 (C0580-12) supplies an ignition feed to the alternator (C0226-2) on a green/yellow wire. This feed protects the alternator should a wiring fault occur.
Fuse 7 (C0580-14) supplies an ignition feed to the ignition/no charge warning lamp (C0233-16) on a white/green wire via header 285. The ignition/no charge warning lamp (C0233-17) is also connected to the alternator (C0226-1) on a yellow/brown then brown/yellow wire. This feed passes to earth via the brushes and regulator within the alternator, completing the ignition/no charge warning lamp circuit. The warning lamp will now illuminate.
When the engine is started, the magnetized rotor turns within the stator windings, generating a 3 phase alternating current (ac), and a voltage that rises rapidly with rotor speed. The field diodes in the rectifier pack convert the ac current into dc current, flowing through the field windings. This causes an increase in the magnetic influence of the rotor, resulting in self-excitation of the alternator. The field current increases with rotor speed and thus increases the generated current and voltage until the alternator is fully excited.
When the voltage applied by the alternator to the ignition/no charge warning lamp equals that provided by fuse 7 of the passenger compartment fuse box the warning lamp is extinguished. This shows the alternator is producing battery charging current.
When the battery is at a low state of charge or the current draw from the electrical functions of the vehicle causes a voltage drop, the alternator automatically charges at its maximum rate (dependant on rotor speed) until 14 volts is achieved. When demand drops, the current output is reduced.
Battery charging is achieved on a brown wire from the alternator (C0183-1). This feed passes across the starter motor (C0178-1 & C0631-1) and back to the battery positive terminal (C0192-1) on a red wire.