350i Starter Solenoid Wiring

[hk350i]

I have just replaced the starter motor and solenoid on my 350i with a Edge performance starter motor. The solenoid only has one blade contact on it. My previous starter had two, one for the white/red wire and one for white green wire. I have connected the white/red wire to the starter solenoid and it works fine with a vast improvement in cranking speed and the engine firing quickly.

What is the purpose of the white/green wire as I cannot work out what it is connected to? Will it do any harm to leave it disconnected? This wire is not shown on any of the Rover or TVR wiring diagrams that I have found.

[GreenV8S]

Could the spare wire be an earth? Presumably the new solenoid is earthed through its casing.

[hk350i]

It is not an earth. When the solenoid is fully activated ie 12V applied to the motor this terminal also gets 12V. My 280i also has two terminals on the starter solenoid and it looks from the wiring diagram for this car that the full 12V is applied to the coil, bypassing the ballast resistor for a stronger spark during cranking of the engine. On the 280i it also seems to have something to do with the engine run sensor.

Is there an ignition ballast resistor on the Rover engine and if so where can I find it?

[hk350i]

It is not an earth. When the solenoid is fully activated ie 12V applied to the motor this terminal also gets 12V. My 280i also has two terminals on the starter solenoid and it looks from the wiring diagram for this car that the full 12V is applied to the coil, bypassing the ballast resistor for a stronger spark during cranking of the engine. On the 280i it also seems to have something to do with the engine run sensor.

Is there an ignition ballast resistor on the Rover engine and if so where can I find it?

[Mytvr]

The extra wire from the starter solenoid feeds the fuel pump relay when the starter is operated so as to maintain fuel pressure when cranking.

[hk350i]

Before I fitted the new starter I assumed this to be the case particularly as the wire was green and white (the same colour as the wire that energises the fuel pump relay). I tried buzzing the wire through between the end at the starter solenoid and the end at the terminal of the fuel pump relay and got open cicuit.

During cranking the fuel pump relay seems to be switched by virtue of the 12V generated by the green and white output from the fuel injection steering relay. This 12V feeds arrives from the white and red wire getting 12V when the ignition switch is turned to the cranking position. This is consistent with the published wiring diagrams.

Your information that the green and white wire is used to energise the fuel pump relay is completely sensible, because with this wiring configuration the fuel pump energises at the same time as the starter motor recieves power and hopefully starts to turn. With the apparent wiring configuration in my car the fuel pump will be running even if the starter solenoid is defective and fails to engage the pinion and energise the starter motor.

The wiring on my car remains a mystery and I shall resort to physically tracing the wire to see where it ends up. Your suggestion confirms my initial thinking and will at least help target further investigation. Resolution of this problem is not too urgent as the car starts and appears to run fine without the wire connected and is under long term restoration so not used as a daily driver.

Thanks for your help.