Anything and everything GT6.

Alternators, dynamos, lights, wipers, etc.

When it was time to replace the solenoid on my late MKIII, I used type ST4 (happened to have one) which does not have the extra terminal to fit the lead that supplies full battery volts to the coil during cranking (bypassing the ballast resistor/ballasting lead in the harness).
The modification consists of fitting a rectifier diode from the starter motor connection to the lead that hitherto had a place to go on the solenoid. The anode end of the diode goes to the starter motor connection.
The arrangement works very well, albeit with the loss of nearly a volt across the diode. The diode is needed to prevent the very low resistance of the starter motor winding short circuiting the ignition coil when cranking ceases and the supply is removed from the starter motor.


Peter