Hey looking for any help here I’m pulling my hair out.

just bought a 1997 1500 5.2 2wd with a blown engine and grabbed an engine and transmission from a 1998 2wd swapped in the the complete drivetrain and realized there were some differences in the years, so we swapped over everything that was different from the 97(aside from intake but have the other temp sensor plugged in) so all wiring would plug and play still no fire

so, swapped distributor, crank sensor, coil, fuel rails, throttle body, have all sensors plugged in( including the speed sensor that doesn’t fit in the 1998 transmission). Checked asd system and have the two 5v references at the pcm as well as the 12v, when the key is turned on the coil gets the 12v for the initial 3 seconds then cuts out and does not come back when cranking, so thought it might be an issue with pcm and swapped that out and still nothing. I’m at also I feel like there’s nothing else that it could be and my help would be appreciated.
I’ll add that the engine used in the swap is a known good engine. Thanks

 

Also have gone through and cleaned all grounds and even added more grounds to no avail

 

The engine wiring harness is still the original 97, correct ?

Do you have the "tach bounce" when cranking ? Or an OBD2 tool with live data to check if the PCM registers a crank signal ?

 

There are some major differences between the 97, and 98 PCMs, they are not interchangeable.

If you see power at the coil at initial key on, but, nothing after that, even with the engine cranking, that's a bad crank sensor, bad wiring, or bad PCM.

 

yes. Original wiring harness from the 1997.

Tach doesn’t move when cranking and don’t have a live data scanner

 

I have changed the crank sensor and pcm with no differences, this truck was running on Sunday when it blew up due to oil pump failure,
The harness is the original one to the truck so I guess I’ll have to try and trace through the harness to find a bad spot from pulling/installing the powertrain, any ideas on circuits to start with?

 

Check for pinched wires between the engine and trans.

 

Does the asd relay come on if you don't wait 3 seconds and crank it right away? Asd relay should be on during crank.

 

found a bundle of spliced grounds broken where the bulkhead wires lead to transmission harness, reconnected them and it fired right up. Thanks for the help.

 

Awesome.