Looks like an interesting community, I thought I would try to get some advice. We purchased a 2003 Chevy Trailblazer on the cheap because it had an engine fire. Looked like the air conditioning hose was leaking around the connection between tube and hose, a coil sparked and lit the truck on fire. This was judging on the burns. Either way, I went to a yard, found a Trailblazer with the same 4.2 six, pulled what I could of the harness, cut the rest. Do not know what pinout file I had when I did it, but the only thing that did not work was the indicator light for the gear selector, that I ended up adding a ground to get to work. But when that happened, I started to realize that just using the 2006 neutral safety switch and the 2006 forward o2 sensor was not the answer. Now we have to get to emissions. Yesterday, the battery started to overcharge, got to 19 volts, ended up needing to replace the alternator, but now there is a surge and the codes are screaming 02 heater resistance. So I got subscribe to alldata and got the o2 schematics to see that the wiring is coming off of different pins, at least it looks that way to me. Cant get thru emissions with the check engine lite on so it is time to start digging again. I just thought I would find a place to post this and see if there are any ideas about needing to look into the pins. I did take the harness and pcm from the donor truck that turned out to be an 06.