Starter keeps spinning after ignition

Hi all, I'm helping my neighbor who has a 2012 Tundra 5.7L/auto/4x4.

He's having an issue where the starter continues to spin after the engine starts. If I pull the starter relay after it turns over the starter disengaged and the engine sounds just fine. Otherwise the starter just keeps on spinning. We assumed it was a bad starter and replaced it with a brand new one, same issue.

Also of note is that if we start it, pull the starter relay and try to put it in gear, it shuts off immediately.

Since pulling the stater relay stops the stater from spinning, I'm leaning toward ignition switch? I just don't know why it dies if we put it in gear.

 

Grounding issue maybe?? I'm just stepping into a similar situation with my 07 5.7L. I'm having a fail to start and a start, and other times a constant starter engagement. This has usually happened when I wiggled the ground terminal when the truck fails to start. I think I got it this time, since I've had an issue where if I turned off the truck and tried restarting right away, it would no longer start, wiggled ground and it started right up, but if I tried to turn it over 3 or 4 times with no start, once I wiggled the ground the starter would go 3 or 4 times before starting.

As a troubleshooting method, I would make sure that ground is on tight as to have consistent contact with the battery post. If this is good, then I would try checking the Crankshaft Position Sensor. I replaced mine with an aftermarket one long ago, when I got the code when my starter died, but when it failed to start then, I saved my OEM one placing it in the box and stored it away, cuz I'm a hoarder like that. Recently this no start issue I started getting the same Crankshaft code that has been intermittent, along with its friend Camshaft position sensor A and B for both banks. I think it turned out to be the gasket in the Crankshaft sensor that failed and was probably shifting in its shaft losing contact with the Crankshaft and giving a false reading of where the Crankshaft is. This is my assumption, I'm not a mechanic, but so far in 3 days it hasn't come back, and the truck starts and shifts even better.

 

With ignition on, not start, check for voltage at relay trigger or start wire pin. If voltage is there you likely have a bad ignition switch. If no voltage, check for voltage from relay to solenoid trigger wire pin, if voltage there, you likely have a bad relay. If no voltage, you have a sticky solenoid. Wire diagrams are here. Click forums, scroll to garage heading. Scroll to electrical subheading and all wire diagrams are there.

 

So after replacing the starter and the ignition switch (btw you DO have to take apart the entire steering column to get it out, I should have done a write-up), we figured out the problem was our own fault. It essentially was a grounding problem.

Neighbor had a problem with squirrels chewing up his wiring in the engine bay (twice). After the second time fixing it we put a metal cage around the wiring harness near the ECU on the firewall. Apparently with enough vibration the edges of the cage were contacting the metal test pins and shorting things out. Cage was removed and everything functions normally.