The external regulator (control box) is required only on cars fitted with the 16AC alternator, it regulates charging voltage and current to prevent battery overcharging. Cars with the later 16ACR alternator have the regulator built in and do not use the external unit. If converting from AC to ACR, the external regulator is bypassed but typically left in situ for appearance.
Fusebox
The two-fuse fusebox with cover uses 35-amp and 50-amp fuses. Located in the engine bay, it should be inspected regularly for contact corrosion, a common cause of intermittent electrical faults. Both fuse values are available.
Switches and Transmitters
An oil pressure warning switch and a water temperature transmitter (North American specification only) are mounted on the engine block. The oil pressure switch uses a banjo fitting with two sealing washers.