The solenoid could be bad. A loose wire, ground, or the switch itself is bad.
Did you attach the electric contacts to your starter? Do you have a good battery? Someone needs to check out your electrical system.
Yes, if the battery is weak it will not provide enough electrical energy to properly operate the starter.
Check the battery cables or starter.
Dead battery? Loose or dirty battery cables? Bad starter solenoid? Bad starter? Neutral switch?
Yes.
Voltage Regulator?
Maybe you have a problem in your main wiring harness. No fun.. Could also be an electrical sensor.
Double check the battery cables at the battery and at the engine, be sure they are clean and tight.
try changing the battery, your battery might be bad you never know, it might not hold a charge The starter relay needs to have good contact. Even though it may click, the contact is dirty and not good enough to transmit strong electrical power to the starter. Change the starter relay which is connected to the positive cable to the battery. Do not confuse the starter solenoid with the starter relay.
The function of a battery is to provide electrical energy to devices which are connected to it.
may be on top of the starter and replaced with same. Follow the + battery cable it will connect to the solenoid
In the car electrical system, the starter motor is the first stop after the battery, so the problem has to be with that.