5.3 to 6.0 swap

[Martin Jarrett]

Okay, so I’ll start off, I had a 5.3 in my 03 Silverado 1500 that locked down on me because of oil pump went out. So I pulled a 6.0 from a 03 Silverado 1500HD. Swapped flywheels so I could keep my just recently billet built 4l60e... so I get the 6.0 in and all buttoned up to trans and all wires connected. Well now I can get it to fire for only a second. It will fire then shut off. No DTCs stored. Can’t figure out what’s going on. Have reset the pcm with the key switch procedure. Anyone have some input?

[carkhz316]

Does it start, run for about 1 second, then abruptly turn off? Is the security light flashing at any time during this?

[SierraHD17]

Why did you swap pcms?  You need the original for the 4L60e tune and the 6 liter will run on the 5.3 tune no problem until you get someone to update the settings...