Help with my 5.3 swap.
 

So i have a 03 silverado the LS1 knocked so I bought a junk yard 06 LS3 i was told this is same motor . So I used all my engine stuff intake sensors everything i just used the long block from junk yard motor ! It get fuel but no spark and the code reader plug says cant connect i checked all fuses all grounds . Why wont this start and if this is a computer thing why if its all my motors parts ?? Need help please !!

If you’re still needing an answer here -

At the ignition coils, Check for battery voltage on the pink wire with the key on. Reading should be within 0.5 volts of battery. If no voltage is present, check fuses INJ 1 & INJ 2 in the underhood fuse block. If those fuses are good, there’s an open in the circuit (harness) between the fuse block and coils.

Check for a good block ground on the black wires - anything more than 0.2 ohms resistance requires further investigation. Don’t forget to touch the meter leads together and subtract the resistance to obtain an accurate reading.

If those are good, the crankshaft and camshaft position sensors are the inputs used by the PCM for spark control. I’m not sure of the wire colors, but with the key on, both sensors should have 11.5 - 12.5 volts on 1 wire and less than 0.5 volt on the other 2.

Thank you Gumby22
 

So got the engine to run had bad grounds at rear of engine ! Runs good but have no gauges drivers window wont go up and security and fob dont work!! Any ideas here ????

Is the cluster completely dead (no lights or gauges at all), or will it complete a self test (all lights turn on for a few seconds and all gauges sweep) when the key is first turned on?

Is it only the driver window that’s inoperative or can the other windows be controlled using the driver door switch?

What do you mean security isn’t working? The engine wouldn’t stay running if the security system isn’t working because the PCM disables the fuel pump if it doesn’t receive the correct signal from the BCM.

Fob could be related to the problems you’re experiencing or may just have a dead battery. I’d focus on resolving the other issues first.

Gumby22
 

The gauges move and none of the windows go down the window locks don’t work the check engine air bag abs and battery light are all on and the code reader plug wont connect to the DLC when you try to get a code and im sorry the security light blinks ! And i tried another BCM but it didnt work