It could be starter, battery, keyswitch, neutral lockout switch or electrical connections.
Possibly a neutral lockout switch, possibly a bad connection, possibly an ignition switch.
The starter relay is integrated into the starter. Have you checked the neutral lockout switch? If the neutral lockout switch is faulty or adjusted wrong the starter will never engage. It could also be that the starter wires are cross-connected. Using a volt meter, make sure you are getting voltage to the starter bendix when you attempt to start the engine. If not, start backtracking to the keyswitch to see where you DO have voltage.
Align the neutral lockout switch.
On the starter. It's actually a PART of the starter. If it's not engaging at all, (no click) it could be the keyswitch, a dirty or loose connection or the neutral lockout switch.
If it's not cranking at all, it could be the keyswitch, a bad connection somewhere, the starter or the neutral lockout switch.
Starter problems can be caused by several things: Weak battery because of battery failure or alternator that is not charging the battery. Falty connection between the battery and the starter. Solenoid failure or bad connection on the solenoid. Starter failure. Neutral lockout switch failure. Bad connection between keyswitch and starter.
Starter lockout relay, next to the battery.
what are the symptoms of a bad temperature switch
If you are saying that you have reason to believe that the battery is charged, yet the starter won't crank the engine, it could be: starter, Neutral/park lockout switch, Bad electrical connection or Keyswitch.
Yes, there is a lockout switch that will not allow the starter to engage if the engine is not in Neutral or Park. If that switch fails, is loose or not adjusted properly the engine will not start.
It could be the starter, keyswitch, neutral lockout switch, wiring connector or any of a number of other problems. Unfortunately you have to just track it down.