I'm having very intermittent lack of starter rotation on a Toyota
T-100. Over the last 14 years I have replaced the contacts it the
solenoid and more recently (1 to 2 years) replaced the starter.
For trouble shooting I have a meter with one lead connected to the
bolt on the solenoid and the other to the frame.
The plan is; if I can get it to malfunction while trying to start it
and the voltage on the solenoid is 13.7v vs 10.7 then I know the
solenoid contacts didn't connect (if they clicked) or the starter is
open (less likely).
If the solenoid clicks and the voltage drops to a low value then I
probably have a bad connection in the wiring.

So far I have engaged the starter 25 times without malfunction.
Letting things cool, then I'll try again, if I hit 100 my work is done
for this go round!

Question 1) The battery voltage sets at 12.7, when I energize the
starter it drops to 10.7.
Is that a normal voltage under starter load?

Question 2) In the old days, you could remove the coil wire to run a
starter without starting the motor.
How do you disable the spark on these newer vehicles without a
distributor cap? (newer 1997) :-)

Mikek