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No crank after engine swap

Project Chummins

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Project Chummins Enthusiast

Project Chummins

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Working on an 06 Silverado 1500 4.8L 4WD at work. Was told bad motor. Started up with the key and drove it in the shop. I'm assuming blown head gaskets by the way it was running. Anyway got a cut out from a wrecked truck. Another 4.8 out of another 06. I pulled the plugs out of the fuse box, pulled PCM out of the mount (DID NOT DISCONNECT WIRES FROM PCM) sat PCM on top of the motor, pulled the whole dog house off as a whole. Proceeded to switch the motors out, got it all back together, and now it will not turn over with the key. Put an exposed relay in it, closed the circuit, it turned over and fired right up.

 

I'm getting power out of the ignition switch

Power through the crank fuse

According to my Modis the PCM is receiving the command to crank

RELAY IS NOT CLOSING.

I have power to the other 3 terminals of the relay, nothing out to the trigger wire

 

What am I missing??? It's driving me nuts

Project Chummins Enthusiast

Project Chummins

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Security light is not on

 

It's acting as if it's in gear

 

It kills the dash and headlights when I turn the key to crank.

 

PCM reading trans is in 3rd gear? Is that normal?

 

I DISCONNECTED ABSOLUTELY NOTHING FROM THE TRANSMISSION AT ANY POINT IN TIME.

Project Chummins Enthusiast

Project Chummins

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I tried case relearn through my Modis and it's saying trans not in park. I guess I should've included that. That's probably why it's not cranking I guess more so the question is how could the PRNDL switch possibly have gotten messed up when I never touched it.

Dnt Senior Enthusiast

Dnt

Posted
Posted

Neutral switch may have got bumped, turn the key to start and move the gear shift a bit both ways and see if it will kick over. Hope it is that easy for you....

Project Chummins Enthusiast

Project Chummins

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I lifted it, ran it through the gears while running.

 

Modis reads as follows

Column in park reads 3rd gear

Reverse reads 1st gear

Neutral reads 1st gear

Drive reads 3rd gear

3 reads 3rd gear

2 reads 2nd gear

1 reads 1st gear

Project Chummins Enthusiast

Project Chummins

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Just went out? Just like that? In a day while it sat in the shop? I mean I guess I've seen crazier stuff but it seems unlikely. No sort of electrical quirks that could've caused it to not read? Shouldn't I be seeing a code for it if it was bad?

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