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I need a little identification help with this stock harness. I pulled a 5.3 out of a 2005 GMC 4x4, and I kept the harness intact.
That was almost a year ago. Now I'm getting ready to hook up everything again, and I couldn't figure out what a few of the connectors went to. I don't imagine they will be needed to run the engine, but I would like to know what they are.
The red boxes are the connectors that I assume plugged into something on the truck that I didn't remove because there doesn't seem to be anything engine related that they would plug into. I have pretty much figured out what all the connectors in the yellow boxes plug into, but I don't necessarily know what they are. Any help would be appreciated.
Whole Harness
One of those is probably the air re-circulation door for the AC does one of the wires go to pcm blue connector pin33
The plug near the a/c compressor is the a/c pressure sensor.
T-case
That appears to be the VSS
Last pic
The top connector should go to the transfercase for 2/4wd
The next 2 connectors go to the body harnesses, check the FAQ sticky post 13 it should have a guide that maps out all the pins for those 2 connectors.
I`m not sure what the last plug is for.
Go here if you haven't been already. http://lt1swap.com/
This guy's website is a gold mine of info. He has everything listed as far as the pinouts and their descriptions. Study that site and you will find out what to connect to external and what to remove from your harness.
Thanks for the replies. I'll probably just have to trace those to the pcm connector to see what they are. It is good to lay this out and really start looking at how it's put together. After learning what all the sensors are, it really doesn't seem that complicated.
Quick question on the VSS. I have an NV4500 in the truck that this engine is going in. The VSS plug on the 5.3 harness doesn't fit the VSS plug on either of the NV4500's that I have, so I assume that they changed the type of connector at some point. The question is when? I need to hit the junkyard and scrounge up one of those connectors to splice in, or there might be an unneeded one on the harness that I could use.
Thanks for the replies. I'll probably just have to trace those to the pcm connector to see what they are. It is good to lay this out and really start looking at how it's put together. After learning what all the sensors are, it really doesn't seem that complicated.
Quick question on the VSS. I have an NV4500 in the truck that this engine is going in. The VSS plug on the 5.3 harness doesn't fit the VSS plug on either of the NV4500's that I have, so I assume that they changed the type of connector at some point. The question is when? I need to hit the junkyard and scrounge up one of those connectors to splice in, or there might be an unneeded one on the harness that I could use.
I have found in my experience when trying to find connectors I'll go to oreilly.com and search the part, in your case the vvs connector for that trans (not the engine or donor car) and it will give you information about it (numbers of wires, ect.) and shows pics of it hopefully. Google is also good for this under images.
But back to your harness the link I provided will tell you what the connectors are. If he lists say, C1 pin 37-EVAP, then trace that wire to that connector and you have ID'ed. That guy has the complete pinout for those computers. I coudn't have done my harness without his site.
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Help with stock harness 
