The road from the ignition switch to the starter is a long and complex one. The starter relay aka theft deterrent relay, the transmission range switch, the ground for the relay coil that comes from tdr ( theft deterrent relay), all play a part in the starter working.
I suggest you go to shbox.com and study the starting part of the starting and charging wiring diagram. Study the diagram and see which component, wire or connector is not working as it should.
If you note on the wiring diagram, when you turn key to start, power goes to tdr points and through transmission range switch to tdr coil. Both must have power to have starter work. Then tdr supplies ground to tdr coil and points close and then power goes to starter solenoid on purple wire.
I suggest you go to shbox.com and study the starting part of the starting and charging wiring diagram. Study the diagram and see which component, wire or connector is not working as it should.
If you note on the wiring diagram, when you turn key to start, power goes to tdr points and through transmission range switch to tdr coil. Both must have power to have starter work. Then tdr supplies ground to tdr coil and points close and then power goes to starter solenoid on purple wire.