Page created by T August 27th 2014:
The Starter contacts in pre-HQ Ignition Switches can burn out. As a result the Starter stops working. Owners then fit a Relay which engages the Starter and extends the life of the Ignition Switch.
Starter Relay Advantage:
The Relay can carry more current than the Ignition Switch, is cheaper and is more readily available than the Ignition Switch. A Relay only needs a small current to be activated which extends the life of the Ignition Switch. Wire the Relay to the START connection on the Ignition Switch.
The Ignition Switch has a separate contact for the Starter which is only activated in the START position. That provides isolation of the Starter when the Key is released to the ON position. If this contact becomes heavily burned, the Starter ceases to work properly. The option is to wire the Starter to the yellow Wire connector as a workaround. That makes it vital to isolate the yellow Wire and the Starter Wire with a Diode so that the Starter will stop when the Key is in the ON position. Use this circuit if the START Contact doesn't work anymore.
Starter Relay Problems:
A Relay only needs a small current to be activated and even less current to make it remain activated. If the Relay has been connected to the yellow Wire Contact on the Ignition Switch, the Relay will hold in after the key is released unless a Diode is fitted. The Diode prevents current from the pink Ballast Resistance Wire from activating the Starter by only allowing current to flow in the proper direction.
By adding the 6 Amp Diode to the circuit above, the hold in problem will not occur. Always use the fuse to provide circuit protection.