Next time it does that, moving the gear selector as you try to start it. It could be the neutral safety switch that's just being temperamental.
If THAT's not the problem, check the starter. A failing solenoid can act that way, but don't bother to replace JUST the solenoid. It's integrated into the starter and not worth the trouble it takes to replace just a solenoid... just have the starter tested.
If the engine will not turn over, it is either the battery or the starter. Turn on the headlights and then have someone try to start the vehicle while you look at the headlights. If the lights go dim, the battery is bad. If they do not, you have a problem with the starter. Remove the starter and have it tested. The flywheel would only be the problem if you hear the starter engage and spin. That can be a broken tooth on the flywheel, or a bad starter drive gear. If the starter does not engage at all and you hear no click, you may have a bad ignition switch.
If the starter is not properly mounted then it will not properly engage and release the flywheel. The started may need to be shimmed in or out.
The starter is failing to push/extend the teeth to engage the flywheel.The 'bendix' is bad.See "Related Questions" below for more
Replace the starter
The starter drive has broken, replace starter.
If the starter spins but won't engage, then the Bendix is not engaging the flywheel. Remove the starter and test to see if the Bendix thrusts out, and check to see that the flywheel does not have chipped teeth.
thanks how many holding blots and where bad bendix (starter drive) if the spring in the starter bendix is weak or broken it will not engage the flywheel; but the starter will turn normally. bad thing is ,you have to pull the starter..good luck..
starter motor need overhaul
Toyota previa starter motor wont engage
1. To engage the starter with the ring-gear on the engine before the starter is turned on. IE to "pre-engage" it. 2. To turn the starter on once it is Engaged. This prevents/reduces damage to the gear-teeth on both the starter and the ring gear.
Aplly battery voltage to it, it should jump, engage.
Starter selenoid no good