Im going to pull the started back off the block here in a few and verify it spins.

Basically the red head wire is constant 12v from the battery and the small yellow wire is switched 12v from the starter relay.

Im beginning to start thinking again about the engine or trans locked up but I spun the engine over my hand so that doesnt make sense. What makes even less sense is I drove it home fine with no issues so how could it have locked up? Oil levels are perfect.

 

You didn't lock up - you'd have heard something abnormal on your drive home or at least when you shut it off.

It's electrical - could be PCM. But I'd still start with the starter and the route power takes to it...

 

 

Ok, really confused here.

So lets recap, then I flip the key, the starter does engage. I have 12v on the main start motor wire. Fuse 14 is good and feeds 12v to the starter relay at pin 30. I have 12v at pin 30 and if I use my meter leads and jump 12v from pin 30 to pin 87, again, the starter engages and clicks. Remember the starter has already been swapped out with a new one. I can put a socket and breaker bar on the crank bolt and rotate the engine by hand and while it isnt total free moving because there is compression, it does rotate.

So what am I missing here?

 

So if there's power to the Starter when the key is turned, the starter was replaced (assuming it's not a dud), and the engine turns by hand... Any chance the starter ring gear could be binding in some way? If something's not lining up quite right, might be enough to draw too much amperage for it to turn. Seen it before with bushing going out but I don't know how the gear is installed in our trucks.

 

I pulled the starter from the block and used jumper cables to provide the ground to the starter, with a bump of the key, the starter gear comes out but does not spin.

I have verified V on the main starter motor wire 2x but now I guess it is time to check voltage drop and resistance. I did use jumper cables to test my original starter and it works fine. Looks like main supplying V is the issue right now

 

If you bench tested the starter, and it works just fine then a bad starter is ruled out.

When you pulled the starter and tesed it with wiring from the truck, did you check the voltage reaching the starter?
Where was your ground connection? Block or battery?
If Block, you could have a poor connection from the block to chassis.

Have you checked the voltage at the battery while the starter is engaged?
(Voltage drop?)

Check the voltage at the starter (Both Red wire and Yellow/Grey wire) while key in "Start" possition. (2 man job)

If you find a voltage drop at the starter Yellow/Grey wire, then work your way back to the realy to see if there is a voltage drop at 87 or 30. (Could be pitted contacts in the relay that you cannot see.)

I am pretty good with electrical troubleshooting if you need additional help.

 

Measure the resistance over the motor at both the solenoid lead and the motor lead.

If you get Zero then the starter is shot, otherwise it is likely okay.

If it is okay, then we need to hook it up and check voltage coming to the solenoid and the motor lead (red and yellow) to ground and see what the voltage is, if it is 12V then you are getting power in.

Now check the ground connection and see if you are getting voltage at ground (ground connection to chassis direct), if you do not get any voltage there then your starter motor is bad.

If you are not getting voltage into the motor (red wire) then you're TIPM is not allowing voltage to pass through, which may indicate that there is something wrong there. Might want to pull the C-Codes and see if it will give you a hint as to where there might be an open circuit.

My bet is you are seeing a voltage drop at the 30 to 87 pin on the stater motor relay which tells the TIPM not to spin the motor...

 

Weed, try switching the relay around with another one in the PDC. Also, take a jumper cable and attach it from the starter housing to a chasis ground area and eliminate the engine to chasis ground.

 

Ok, ladies. I got it figured out. For the record, I had already swapped relays around. Also note, I over complicated things.

The clicking of the starter should have told me everything electrically in the starter motor circuits was fine. However, I went through the process anyway and verified everything.

Resolution? Bad contact at the end of the start motor cable to the battery post. Voltage was verified at the beginning of that cable on the post AND at the post on the starter. However, due to the bad connection, it wasn't good enough to engage the actual starter motor itself.

I only realized this after pulling the starter from the engine and after flipping the key, watching the starter gear come out but not spin.