Hello all - I ran into a weird one, looking for a 2nd opinion.
i'm not an engineer, but pretty decent with 12v automotive stuff.

was working on a friend's car (stock 1969 Torino), and the relay stuck. I hopped out and unhooked everything, and whacked the relay to free it up.
verified relay was no longer stuck.
at that point, wanted to be sure everything was okay (I had just hooked up a new shifter with a NSS), so pulled out the voltmeter and went at it.

using the continuity beep/tone setting, I kept getting tone at the "I" signal, with the key in "run".
so I started unhooking wires.
I ended up with *all* wires removed from the relay, except the hot feed from the battery. and i'm somehow still getting continuity beep on the disconnected "I" terminal when the key hits run.
finally - I unbolt the thing from the firewall.
and it behaves exactly as it should.
verified the same behavior on a spare relay I had laying around.

I had a buddy come over to double-check my work. he said he never tests via continuity, he just measures voltage. he bolted it back down, hooked everything back up, and its working fine.
my brain exploded.

 

1st thing. Why are you checking the "I" terminal? All that is for is to put a solid 12v on the ignition coil when cranking. In other words, the wire hooked to the "I" terminal is not "feeding" the "I" terminal, the "I" terminal is feeding it. It leads to the coil + terminal and puts 12v on it when cranking.

The "S" terminal is the other small terminal that gets the signal from the keyswitch and the neutral safety to crank the engine.

And your friend is correct, it is much better to troubleshoot circuits on the vehicle doing voltage tests. Continuity is only good for individual component testing. The only thing I would use continuity for around the starter relay, is to put the meter in continuity, and then touch one lead to the mounting foot and touch the other lead to the "S" terminal, just to verify the coil inside is good.

 

Argh- I should have known i'd mix the terminals up. I meant "S", not "I", sorry.
i'm struggling to understand how the continuity test is different from the voltage test.

 

Continuity is really only good for testing the relay itself. To verify if the windings in the relay are good. If you do a continuity test with the wiring from the vehicle connected to the relay, there is no telling what you will get. Your meter sends out a voltage in the continuity test. This voltage will go up backwards through the wiring in the vehicle, searching for a place to go to come back to the other side of the meter, and it will probably find a place, and give some weird reading that you really can't interpret. If you could isolate a certain run of wire, and disconnect it on both ends, then you could run a continuity test on that certain run, butit can't be connected to any of the circuits in the vehicle, it has to be isolated.

If you have two meters there, check it out. Put one meter on continuity, and put the other meter on a low voltage setting. Touch both of meter leads together, red to red and black to black, you will see the meter set to read voltage detect a voltage from the meter in the continuity mode.

 

I've learned something today - thank you Dave