My 02 Alero 2.2 won't start....replaced battery and had the starter tested which is fine...could it be the timing chain?

Have you checked to see if you can turn the crank with a wrench ?
And are the cables good from the battery to the starter ?

Check your battery connections at the starter. It may not be getting the needed volts. Just make sure they're clean and tight at the starter and the battery both. Good luck!

Park neutral safety switch maybe be the reason for the no crank ! Try putting the vehicle in park ,then try to crank the engine . Testing the electrical circuit is the best way to trouble shoot this problem , along with do a voltage drop test on the starter circuit ! This will test the battery cables an connections .
Starter Voltage Drop
How to voltage drop test starter motor circuit
Does it have a manual or automatic transmission ? Manual ? clutch switch . Looking at a wiring diagram I also see a starter cut relay !
http://www.bbbind.com/free_tsb.html Free wiring diagrams . Enter vehicle info. year , make , model and engine size . Under system click engine , under subsystem click starting . Then click the search button , then click the blue link ! Check the starter cut relay also . Videos on youtube showing how to test a relay controlled circuit !

You need to have your flywheel: replaced.Your starter motor engages against the fly wheel at the back of the motor. Every time your motor stops it tends to be in the same few positions (just the way things work) so there is more stress on some parts of your fly wheel than others. Because of this the teeth wear out on the fly wheel which means the starter can correctly engage on the fly wheel which is the grinding noise.

Are you saying the engine will not crank, or not start ?

If the engine won't fire up, but your starter turns over, you may want to check your timing unless you have a check engine light on. If the CEL light is on, have the codes scanned.

If the engine won't turn over with the starter or it clicks, have your battery tested at autozone or advanced auto parts. Replace the battery if it is bad. Else, have your starter tested.

If the engine still won't turn over and the battery and starter are tested fine, you may have a blown fuse, bad ignition switch, or a failed relay.

If the engine fires up but randomly dies and starts back up, you either have a failed sensor, failing fuel pump, clogged fuel filter, bad plugs or wires, or a failing ECU.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

Possible causes are: 1. Loose or corroded battery cables. 2. Bad starter 3. Dead battery. Try tapping on the starter with a hammer while someone is holding the key in the start position. If it starts then replace the starter. Thanks

Hi, odds are your solenoid has shorted out. Remove the starter and have it tested at your local parts chain. To remove the starter, first remove the negative terminal from the battery, then remove the wires from the solenoid. Then remove the 2 starter bolts--they thread in from the transmission side. See the pics below, and let me know if you have any questions.

This sounds like there is a dead spot in your starter. The easiest way to resolve this issue is to replace your starter. Many times, if you take a lot of short-distance trips over the life of your car, the wiring inside the starter itself will wear (short trips means starting it more often, causing a lot of wear over time). Then the inner wiring of the starter wears too much, it forms a "dead spot" -- when the starter is stopped at a very specific spot i will not form the magnetic force needed to torn the starter motor. This is a common issue which can be dealt with for a time if you have to save the money to replace the starter. Tapping the starter, or arcing it with a screwdriver makes the inner workings of the starter jump a little, allowing it to move out of the dead spot and kick over as normal, but it is only a temporary fix. Unless you refurbish electronics for a living, it is very unlikely that you will be able to repair the starter on your own, and such a repair takes some time, so you are better off to replace it than try to repair the starter itself.
As long as the starter does not happen to stop in the dead spot, it will work as normal ... but in time the dead spot will spread, causing the issue to worsen. You can keep forcing it to turn with the two tricks you used until you have had the opportunity to earn the money to replace the starter (or until you have a day off to get the repairs done) .. but over time this can cause more damage to other parts of the car, so I recommend replacing the starter as soon as you can.