Well staring at this wiring diagram for my 70,
theres only two places they both come into close contact for this to happen
is the Ign switch, Or
the other is the 4prong plug for the netural switch,
they both have the same color wires red/blue stripe.
remove the start wire from your sol, (left side small one).
turn key to acc and try your wipers.
Did they work?
No. check start wire with v/o meter and check for voltage.
if it has voltage showing then you possably have the wiper plug connected to the netrual switch wire connector at the firewall connections.
PB