How can I see the diagram of the PCM so i know which pin is which

I check already all three have 12V I think I have a bad PCM again I'll try taking it to see if it have warranty if not I am just going to buy a new one at the dealer I just didn't want to spend a lot of money of it I'll let you know what happen thank you very much for ur help I'll keep u post it

hello again i just got back from the place i got the ecu i install it and this one still giving me 1.9 volts so now i sure its not the ecu that has a problem since i just bough this truck and it looks they replace the ecu or pcm connectors maybe they didnt place them in the correct order i hate to bother u but u r the only one i know that have a truck or blazer that can help me i need to see if u can send me a pinout detail on all 4 connectors color of wire color of connector and pin number please

Finally after digging thru almost all the hardness of the truck I came up to the conclusion that there is a short on the cable that is running to the evaporative sensor, I connect every other sensor that is connected to the 5 volt and all work and as soon as I connect the evap sensor it cut the voltage to 1.9 volts I try starting the truck with out that sensor and the truck runs perfect and smooth but still check engine light because of the sensor is not connected I need to take the whole tank down so I haven't done it I will this week I just wanted to let you guys know and thank you for ur help

Thanks for the update!! Keep us posted please.

Thanks for the help, would never have thought of common ground short, testing tonight