Harness and ecm?
 

I am swapping an unknown year 5.3 into my 86 c10. I have 1 complete engine with a dbc throttle body and another engine with out a throttle body but came with a blue green pcm. The problem is the harnesses from both engines were cut up in multiple areas and missing connecters. So with the help of lt1swap i have put together a swap harness using the 2003 pin out diagram but it seems there are not provisions in the 2003 pin outs for the iac. So i look on lt1swap and they list pcm numbers that can run the iac and of course the one i have doesnt so should i sell this pcm and pick one up from the yard for a 99 to 02 truck or is there a place i could trade the pcm i have for the one i need? Also i dont have o2 sensors or connectors so im not sure what ones to purchase as there are multiple options for differnt year trucks? This is the last thing i need to complete before i start my swap so any help is appreciated thank you.

Re: Harness and ecm?
 

Your best bet is to definitely grab a 99-02 ECM, or 03-04 one that is DBC compatible, but unless it comes directly from a DBC vehicle you cant be sure it is without opening it up.

As for O2 sensors it depends on whether the ECM is set up for isolated grounds or not. Best to grab or at least look at the connectors off the donor and match them.

Re: Harness and ecm?
 

Just for your info, 03 and 04 vans have the blue green ecm with dbc and iac.

Re: Harness and ecm?
 

^not all unfortunately. Fleet vehicles came with some atypical configs. There are return style 6.0's late through 04.5, and DBW vans even early into 03 Time Warner vans, railroad trucks etc that were ordered in 1000's can have strange combos.