Electrics

The electrical system of the car is not standard Morris Minor.  Normally, a Morris Minor has only two 12V supplies available: non-switched (i.e. always powered) or switched (i.e. only powered when the ignition switch is ON).  This system pre-dates even the 'accessory' position of more modern vehicles which was introduced when items such as car stereo units were becoming common in order to sustain their power without the need for the engine to be running, or at least the ignition circuits to be ON.

In the Morris Minor 2000, partly due to the many electrical items which are not standard and the need to power them via their own fused circuits and take measures to disable some/all when 'kill' switches are deployed (for security reasons), several 12V supplies are created.  Additionally, the provision of a stereo head unit and an analogue clock mean that an extra power supply (the 'Auxiliary Power Supply') is required for when the main battery is isolated.  See Auxiliary Power.

IDENTIFYING THE 12V RAILS

• In the case of all additional wiring, it is labelled throughout the car, providing the user with separation of different 12V rails for each purpose and good diagnostic traceability.  

• Each 12V rail is given its own identifier e.g. 12V:0, 12V:1[A], 12V:1[B], 12V:1[C], 12V:2, 12V:3, 12V:4.  These are defined as follows but note that it is still the main 12V battery which supplies all the power to all 12V rails and all electrical systems when it is connected - the Auxiliary Power Supply is only in use when the main battery voltage is not present and only powers selected items as explained in 12V:1[B] below (see details here):

12V:0

• Power derived directly from the battery is labelled 12V:0.  

• This is UNFUSED and is connected solely to the main battery isolation switch.  

12V:1[A]

• The next power rail following the main battery isolator switch is 12V:1[A] 

• It feeds:

  • the Kenlowe cooling fan and Revotec fan controller via their own dedicated 30A fuse and isolation switch, situated under the dashboard on the LHS.  Note that the fan is wired POST this isolation switch but PRE the ignition switch and PRE all kill switches.  Hence, it remains live at all times and could automatically switch on unless this isolation switch or the battery isolation switch in the boot is activated

  • the audio power amplifier (via its own dedicated 80A fuse which is situated next to the power amplifier beneath the rear seat, behind the passenger seat, accessed through the hatch in the rear seat).

  • the dipped and full beam headlights (unfused by Morris Minor original design)

  • the main vehicle fusebox fuses nos. 6 & 8 - terminal #1 of the Auxiliary Power Supply (charging input), Sony head unit ON-OFF quick switch, Sony head unit driver's remote control receiver

  • the main vehicle fusebox fuse no. 1 - sidelights, main speedometer backlights and backlights to all additional instruments and gauges except the tachometer

  • the main vehicle fusebox fuse no. 7 - horn wireless receiver (Rx), horn switch press (in centre dashboard), hazard warning lights, 

  • the ignition switch

12V:1[B]

• Power rail 12V:1[B] is the 12V output from the Auxiliary Power Supply

• It feeds:

  • the analogue clock 

  • the yellow lead (standby power ONLY) for the Sony head unit (i.e. the power which is required to keep its memory, not operate the device).

12V:1[C]

• Power rail 12V:1[C] is the voltage monitor output for the Auxiliary Power Supply.  

• It feeds:

  • the voltmeter via the voltmeter red button such that the voltmeter displays the Auxiliary Power Supply output voltage only when the red button is pressed.

12V:2

• The power rail following the ignition switch 'ON' position is designated and labelled 12V:2

• It feeds:

  • the voltmeter by default so the voltage of this rail is what the voltmeter normally shows.  The voltmeter input is only overridden when the red button is pressed to read the voltage of the auxiliary power supply (see above).

• the second 'kill' switch which is designated KILL#2

12V:3

• 12V:3 is the power rail after the first kill switch KILL#1.  

• It feeds:

  • the starter solenoid only

• It is only live when the ignition key is turned against the spring into the 'start' position, to engage the starter motor and the kill switch KILL#1 is ON.

12V:4

• 12V:4 is the power rail after the second kill switch KILL#2.  

• It feeds:

  • the main vehicle fusebox fuse no.2 - indicators

  • the main vehicle fusebox fuse no.3 - windscreen wipers, fuel gauge (via 10V voltage stabiliser mounted on rear of gauge), oil pressure switch

  • the main vehicle fusebox fuse no.5 - windscreen washer pump

  • the new instruments and gauges plus the backlight to the tachometer - all via a separate inline 4A 3AG fast-acting fuse (0.25" x 1.25")

  • the fuel pump via the inertia switch

  • the fuel pump inertia switch override LED (mounted in boot cavity under hatch on LHS of boot)

  • the ignition circuit (coil and distributor red lead)

  • the Armtech rev limiter