So here's my problem.

I have a '61 mercury with a 292 V8. I can only start it right
now by jumping 12v to the "S" terminal of the starter relay.
I measure about 6v on the brown lead (to the "I" terminal
on the relay) and 0v to the "S" terminal when I turn the
ignition to start.

I read elsewhere that the "I" terminal provides a "boost"
to the ignition coil only at the time of starting. Is this correct
(seem weird)?

I believe I must have a short in the red/blue wire from ignition
switch to starter relay if I get no voltage at key start. Would
that seem logical? Presuming no obvious problems, I think
I would need to test continuity on the wire and replace it
if there is no continuity?

Any help much appreciated. Trying to get this old girl back
on the road.

cheers,
Stefan

 

Welcome to FTE!!!!

Your ignition switch is probably bad.

 

Thanks.. but I should have made clear that I bought (and
installed) a new one - it had exactly the same results as the
old, original one. That is, all the appliances (radio, lights, etc.)
function in the normal ON position, but when I turn it to start
nothing happens.

Since I was only getting 5.5-6.5 volts at the terminal on the
starter relay I figured there was probably a wire problem (possibly
corrosion?).

thanks,
S.

 

Oh ok, then you do have a conector and/or wiring problem
between the ignition switch and solenoid. the 5V-6V you are
measuring is probably feeding back from the coil side of the
ballast resistor.

 

This may help

https://www.ford-trucks.com/forums/s...hreadid=124657

ps
The wire from the "I" terminal does supply 12 volts to the coil during starts. As said you are probably measuring feedback from the coil +

 

thanks very much for the pointers and advice.
I believe it'll prove very helpful.

cheers, S.