I need to add TPS & IAC to my harness but I can't find any diagrams on installing on a RED/BLUE connector engine harness. I found some info on LT1swap but its for the BLUE/GREEN connectors.

My PCM and harness (RED/BLUE) is out of a 2003 3500 Silverado.

 

Have You checked AutoZone's website ,,,,,,they have schematics for any vehicle sold in the US from maybe the 1960's to at least 2005 . Also in this forum a thread titled something like "pinouts and diagrams for a 4.8L" that a few different members have posted links for I believe 5 years of the truck engine harness' .

 

Look at post # 13 (truck pins) in the Swap Fac's .
https://ls1tech.com/forums/conversio...swap-faqs.html