I'm working on a Merc 3.0 that doesn't have 12 volts, with the key on, at the
purple wire (#5 pin) at the main connector behind the engine.

The ignition switch is fine. Seems like a broken wire between the main connector
and the ignition switch.

Is there any reason why I shouldn't run a new wire from the ignition terminal on
the key switch to the #5 connector pin that feeds the coil/choke/alt.

Thanks for any help
Larry