If you’re using the 12v constant feed from battery and the battery is good*
*If you have applied power directly to the starter and it doesn’t crank then that’s more than likely the culprit, going on the basis that the starter has a good ground then it should always crank if its in good working order and you’ve applied power direct to it. If it doesn’t then the starter/solenoid is faulty. This method of testing bypasses all safety switches etc, essentially you are bench testing it in situ.
If you are using a separate power supply, like a loose battery or jumper pack etc then you have to apply the negative supply to the frame/starter as well for that to work.
I had two starters last year that were faulty and doing similar except the voltage was dropping to 2v when the key was turned to the start position.
*If you have applied power directly to the starter and it doesn’t crank then that’s more than likely the culprit, going on the basis that the starter has a good ground then it should always crank if its in good working order and you’ve applied power direct to it. If it doesn’t then the starter/solenoid is faulty. This method of testing bypasses all safety switches etc, essentially you are bench testing it in situ.
If you are using a separate power supply, like a loose battery or jumper pack etc then you have to apply the negative supply to the frame/starter as well for that to work.
I had two starters last year that were faulty and doing similar except the voltage was dropping to 2v when the key was turned to the start position.