Hello everyone, long time reader but finally acquired a reason to join, a 1995 Del Sol Si w/ a D15B swap with 171k miles on body and only 100k on engine. All the work was done by a previous owner I have no contact with, the car will start right up and run beautifully when jumping the positive on the starter solenoid, but won't do a thing when trying to start with the ignition. This is what I've eliminated so far:
bad starter
bad clutch safety switch (I jumped the top switch with a paper clip and still nothing
bad fuse
bad battery

i tested the current in the 5 terminals on the ignition switch, and got 12v for each at their appropriate timing on the switch, but the black and white cable that I believe goes to the starter relay never gets any power, even when turning the key all the way when it should crank. Would this narrow it down to a bad ignition switch or could it still be something else?

 

Able to jump the black and white wire to see is thats the issue? When you turn the key, does the car try to crank, sorta like the starter tries to engage, or do it do nothing? Maybe not your issue, but when my last civic did this, I had the complete starting system checked and turned out my alternator was bad. Had no battery light on the cluster so never thought it would be my alternator, Once I changed that, never had an issue with the starter again. Perhaps this isnt your problem but worth a check,