Yes, you can use the key on power wire to run another relay and that
will likely take care of things for now. It only masks the problem so
the problem may worsen and come back to bite you later. I would at least
check the connection inside the wiring box on the firewall. The black
wire from the key should have a splice in there that you can find. Find
it and use the hat pin trick to see if that is where your problem in.
The hat pin is used to poke through the wire insulation to inner metal
wire on each side of the connector to check if the voltage is the same
on both sides. It is isn't then the connection is the problem.

Mark

Dan Hall wrote:
> On Apr I bought the van from the original owner in 1993---had around
> 60,000 miles on it.
> Now almost 270,000 miles.
>
> Since I've been informed that the circuit to the coil is unfused, and
> to save tracing this wire all the way back to the ignition switch,
> trying to find the source of the resistance, could I not just use the
> original wire to trigger a new relay to the coil, the relay getting
> power off the hot post in that junction box on the firewall?
> Could even install fuse to protect the system better.
>
> Thoughts?
>
> And I will certainly run some tests to see if anything is shorting to
> ground and to find any possible restriction causing the poor voltage.
> Could a short to ground cause this voltage drop?
> Dan Hall
>
>