Looking for some direction 2000 Blazer

Guys, I don't post up much, but this truck has me talking to myself. History that I am aware of. Vehicle was brought to a shop or a no start. Shop found problem in theft system and decided to attempt to bypass it. They cut the wires at the passlock sensor and jumped the org/blk to the ylw which is the sensor ground and signal respectively. they installed a 550ohm resistor between the two wires. at that point I don't know what else they had attempted but they had this truck for 6 months. Customer has the truck towed in to us. Before I can start diag on this I find a shorted cell in the battery. Replaced it. Then find a faulty ignition switch. After installing that I moved on to the theft. With the ignition switch replaced, my wiring was now new to the passlock sensor as well, so back to stock. I checked my voltages at the sensor while monitoring them on the Tech2. They matched. I had 5 volts with the key off and at the crank position it dropped to .92. Cleared codes and attempted to learn the value. No go. At this point I figured the passlock sensor was simply bad. Replaced the housing from GM directly. Now it starts to get strange. I plug in the new sensor and it no longer reads 5v. It reads a fixed value of 2.5v no matter what the key position is. It never changes. I spoke to a local tech fiend and he said not to worry about that and attempt to learn the value with the new sensor. I did and the truck started. Ran about 40 minutes and the security indicator came on. I knew it was trouble at that point. I shut the truck and attempted to restart. It would not and set the 1361 and now also set a p1321. I did some testing on the 1321 and confirmed a faulty pcm. Installed a reman unit and the 1321 is gone. Still stuck with the 1361 and cannot learn the passlock. The timer is not counting on the tech 2 while trying to do the relearn and the security lamp is lit solid, not flashing as it should be during the learn timer. Anyone have an idea because I am about fresh out.

have you tried the 30 minute key relearn? i have had problems where the 10 minute counter wont work on the sps and the 30 minute one works

Thanks Cheryl, yes I did that procedure about 30 times throughout this ordeal....I just did a video on the truck I will be posting it up to Youtube shortly. Maybe someone has some answers to this demon infested spawn of satan they call a truck.

The pass-lock system will disable the injectors after 1 to 2 seconds. It will start, then stall. It does not disable spark. Do you have spark? Do you get the "Start, Stall"?

I ask because security codes for pass-lock are B codes.

P1361 Is an ignition code.

Thanks Pole. I do understand how the system works. I have fixed quite a few over the years with no real trouble. This truck however, is a completely different story. Check the link and you can see what I mean.

The 2.5 volt regardless of key position. Which wire is showing that? And what are the other two during this time? (3-wire right?)

Hey Paul! Ok, so three wire sensor. RED/white - spec is over 10v Org/blk ground and Ylw is the sensor signal which is the the one reading the 2.5v constant with the new passlock sensor. Yes it is OEM.

Status update? What did the morning bring? Is it still fixed? Or, back to No-Start?