Hi All
Please note that I have just updated the wiring diagram, accessible from the Web page under the header tab ‘Technical’. Most changes have been made around the Starter Motor, but I have added the Alternator Plug and Ignition light for completeness, along with other minor additions..
My previous drawing I accept was a bit vague around the Starter Solenoid, as I discovered when re-connecting mine after the recent engine refit.
Whilst researching this circuit I also found a lack of awareness and information on the Web regarding pre-engaged starter solenoids which, I now know, can have either 3 or 4 terminals. The basic pre-engaged starter is a Lucas M79, but it seems that either type of solenoid may be attached to it. Both types have the smaller post, adjacent to the motor body, connected directly to the motor windings from inside the motor casing, and also the upper larger stud (with ½ inch AF nut) connected to the main battery feed along with the alternator twin feed cables. The solenoid is energised when 12V from the Starter Relay is applied to the large Lucar type spade connector, also on the solenoid, via the Brown/Red wire. This configuration is identified as a 3 terminal type.
On the 4 terminal solenoid, an additional small spade terminal is fitted which is used to short out the fuel pump ballast resistor on the ERA, or the ignition ballast wire on a standard Mini. This additional terminal is connected internally to the motor winding stud on the solenoid and is therefore at 12V whilst the starter is engaged.
Whilst starting, the white/purple wire connected to this terminal applies12V directly to the Fuel Pump on the ERA, thus overriding the normal reduced voltage feed from the fuel pump relay, via the ballast resistor, which is available for normal running and thus prevents overheating of the pump.
I remember some ERA owners on this list querying the colours shown on this diagram as they did not conform to their vehicles. If that is the case I can only suggest that their wiring has been altered, as this drawing has been double checked against the original ERA drawings.
Along with the previous circuit description, which still applies, I hope this helps someone solve a basis electrical engine running problem with their ERA.Turbo.
Regards.
Pete K