My truck just will not start! I have replaced the starter and the solenoid and yet the starter just spins! Engine will not crank at all. Is this wiring or could it be my flywheel?

 

If the starter spins at all, then obviously all the wiring is fine.

 

First inspect the starter mounting bolts are snug ..
If they are snug then pull the starter and inspect it's gear .. Have it tested @ autozone or another of your choice that provides a free test .. If it tests good then
Next pull the spark plugs so you can turn the engine at the front crankshaft bolt freely .. have someone turn the motor for you while you inspect the ring gear on the flywheel/flexplate for broken or missing teeth ..
Post back any results

 

will that work for me? My engine isn't even turning over. I just bought a brand new starter a few days ago.

 

Why did you replace the starter ? If the starter is good and you have confirmed that it's gear is moving out to engage the flywheel and is just spinning then all it could be is missing teeth on the flywheel or the starter gear is not moving out fully to engage the flywheel .. The only other thing it could be is mismatched parts, flywheel or starter are wrong part for the application ..

 

I am not sure that the gear is engaging, could a wiring issue cause the gear to not engage?

 

Did you not see my post?

If the starter spins, the wiring is fine. If the starter was engaging but bogging down, there could be a cabling connection issue, but that's not the case here. There's nothing electrical upstream of the starter motor that controls whether or not the gear actually engages.