Hi, got a 96 blazer w/v6 W/vin. A few questionsplease. I installed a used pcm (checked out and programed for my vin). I am trying to get the pcm to reset the i/m redieness monitors. Oxygen sensor heater,catalyst, and evaporative system are not resetting yet.I am running through the drive cycles.I might need to give it a few more, the paper work says if the battery is disconnected, it could take 5 cycles to set the catalyst.I think i was having the same problem of resetting, can't remember for sure.Anyone ever have a pcm that wouldn't reset?Also, i was having a problem with the engine dying.I believe it is the coil output for the tach, anyone had a similar problem?Any info is appriciated, thanks.

 

Are these the reasons for changing the pcm ??

 

I was getting a P 1351 code. After going through a detailed diagnostic print out procedure and not finding anything I replaced the pcm.I even changed coil,module and crank sensor as a try.This code would set going down the roar and also cranking the vehicle.After changing out the pcm on second day it died a few times.some times it would start back run a little and die, sometimes i would have to let it sit a little time.the last time it died i decided to disconnect the coil wire to the tach .It started and has not died yet. Driven the last 3 days trying to reset pcm (some monitors did reset) Has not died yet.I don't know if the tach is failing( just remembered sun tachs going out from my past)