i have a 04 silverado 1500 my starter says on wan in park on i replace the starter and the neutral switch and still the same way
$100 starter, $50 neutral switch
First thing I would have tried is the $5 starter relay.
Sounds like the ignition key switch has the start position stuck closed, so you must move it out of park and neutral so that the neutral safety switch turns the starter off.
Suggest OP disconnect battery negative whenever parking car until this is fixed. If starter turns on and stays on by itself, & nobody is around, that could cause the starter to overheat & start the car on fire.
The solution is to disconnect the starter from the car’s wiring harness, then to use a volt meter, probing to figure out why the starter’s solenoid wire is being powered up when it shouldn’t. Note that it is possible the problem is actually the starter itself, and the relationship to the ignition switch and transmission selector is a coincidence. Starters can stick in the “on” position sometimes, again very dangerous b/c of possibility of a car fire.
The starter may need shims