2002 5.3 PCM Pinout ?

[Rubidon]

I am using a wiring harness out of a 2002 silverado for my swap and I can not figure out where the gray wire goes from the Engine Coolant Temp sensor. The yellow wire goes to C1 Blue 74, but I get different spots for the gray wire, some say 80 or 63 ?

[nascarnate326]

This may be better suited for a site like ls1tech.com. MIfbody is more social than it is technical.

[meissen]

C1 Blue 63 is going to be either gray or tan. I see 74 being the Engine Coolant Temp sensor signals while C1 Blue 63 is going to be a sensor ground. If you're using 74 for your sensor signal, 63 is the pin you want to use. From what I can tell, a 5.7L PCM has very similar wiring because 74 is used for the ECT on both 5.3 and 5.7 but 2002 LS1 has 63 left blank.

And PS - while we might not be the most technical site, there's plenty of us here always willing to help find the answer and I can't think of too many cases where anyone asked for help and didn't get some.

Edit: From what it looks like, there's two ground possibilities for 63. Either to ground the HO2s or to ground the ECT. Not sure how you can tell the difference, though.

[Rubidon]

Thanks B, my next question is what is an(isolated ground O2 sensor) how do you tell the difference from the harness? I guess it really don't matter because I never moved any wires for the o2 sensors so they are still hooked up right!

Now I know why people get $300 and up to modify these things,this is the first one I did and it took me ruffly 12 hours to do and I still hurt all over from crawling on the living room floor(the only place I have to do it).

And I got a response faster here than I did from ls1tech. I believe it is because we are so social!! Ha Ha

[meissen]

Sounds like you'll be using pin 63 then afterall. So what is it that you're doing exactly? Making your own wiring harness for a 5.3 PCM?

[nascarnate326]

Damn B, I didnt know you knew LS wiring like that!!

[meissen]

I've got a collection of bookmarks. Steve from SB Tuning and Vector Motorsports did an LSx swap in his LT1 car so he was asking about wiring diagrams and what not for an LSx motor.

[sman]

FWIW, not sure how far your in to this, or what your total plans are, but it might be easier to pick up an ls1 harness, I grabbed mine for about $100. Not sure how the 3rd gens are layed out though harness wise. The car harnesses dont have the fuse boxes like the trucks do, if that helps your situation any.

Let us know if you need anything else, I have an 02 harness out in the garage as well as the computer in my car.

[Rubidon]

Thanks B and Sman,

This is a standalone harness (I guess you would call it that) for my 5.3 swap into my '89 Camaro RS. I found a really cool web site and he tells you how to make your own harness. I just pulled one to many!!! LOL This is the last pin to replace and then I have to make a small fuse/relay holder and that part will be done.Then all I have to do is thin down my stock harness primarily for the gauges.

This is the site WWW.LT1SWAP.COM