GENERATOR INTERNAL CHARGING CIRCUIT
As with most vehicle AC generators, there is only minimal residual magnetism in the field (rotor) windings. To compensate for this and to achieve high current output at low engine speed, the field is excited by battery voltage supplied to the generator at the IG terminal. To control the level of field excitation and ultimately generator output, the voltage supplied to the field (rotor) is controlled by the voltage regulator. The voltage regulator senses battery terminal voltage at the B terminal (positive main output terminal), which within limits is proportional to the state of charge of the battery. The regulator then adjusts the supplied voltage between the IG terminal and the regulator F terminal (a continuously variable process) to maintain the positive main output (B terminal) at a constant level. If the field were not controlled, the positive main output would rise to a level which could damage bulbs and ECMs. The regulator compares the output voltage to an internal voltage reference circuit to achieve the controlled output of the generator. (Scheme 37)
Scheme 37
CHARGING SYSTEM
The output from the generator positive main output terminal passes to the battery via the main terminal on the starter motor and then the power cable to the high power protection module located in the luggage compartment. From this module, a short main power cable supplies the battery positive terminal. The return circuit is through the vehicle body and supplementary ground cables. The high power protection module comprises four fuses, each rated at 250 amps. Battery output uses the same power cable as the charging circuit to the high power protection module and to the starter motor main terminal. There are 2 similar cables of lower rating that supply battery power from the high power protection module to the fuse box in the luggage compartment and to the fuse boxes at the front of the vehicle. The interference suppression module (where fitted) connects to the generator positive main output terminal and a ground stud on the rear of the generator. A 3-pin connector is on the rear of the generator supplies ignition voltage to the regulator through terminal No. 2 and output to the charge warning lamp through terminal No. 3. Terminal No. 1 is not used. (Scheme 38)
Scheme 38
SUPPRESSION MODULE
Although the output from the generator is finely controlled and relatively smooth, it is still a pulsed DC output at a varying frequency proportional to engine speed. The suppression module dampens out any ripple which may be sensed on the main output of the generator. This prevents possible interference via the power supply, affecting the radio reception or, where fitted, the telephone. The module is located on the right hand side of the engine compartment adjacent to the generator. It is secured to a mounting bracket by 3 bolts. A fuse is fitted internally to the suppression module to protect the generator output in the event of a short circuit within the suppression module.
VOLTAGE REGULATOR
The voltage regulator is integral to the generator. The battery charging capability has been optimized for charging a battery which is located remotely, in the luggage compartment. The design of the generator and regulator has been finely matched, to generate charging current with very low ripple. This provides the best electrical refinement to the system.
BELT TENSION
Belt tension is achieved by an automatic tensioner. Never apply oil the belt tensioner. Neither the belt tensioner or the belt require service apart from checking the belt wear indicators at each normal service interval. (Scheme 39) The minimum service life of the drive belt is 100,000 miles. There are no special service tools required to remove the generator from the vehicle.
Scheme 39
PRELIMINARY CHECKS
Ensure generator drive belt is within wear limits on belt tensioner and battery is fully charged. Battery cables and connections must be in good condition.
Battery Disconnect Procedure
Each door glass automatically drops 12 mm when the door is opened or when the convertible top is raised or lowered. It is important that windows are lowered before battery is disconnected to allow doors to shut properly.
Battery Reconnect Procedure
Note. Whether one or both cables were disconnected, a minimum of 30 seconds MUST elapse between disconnection of the first cable and connection of the last cable. A clean final connection must be made. Do not allow temporary contact.
- Connect the battery terminal(s).
- Reset the clock.
- Enter the radio security code.
- Cycle (both) door windows up and down to establish the upper and lower reference points. Turn ignition ON. Lower the glass to the stop and hold the switch in the DOWN position for an additional 5 seconds. Raise the glass fully and hold the switch in the UP position for an additional 5 seconds.
- Turn ignition OFF.
XK8
See STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article.
XKR
See STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article.
See STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article.
See STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article.