The latest discovery, important! (See diagram attached) Battery disconnected, waited to discharge, 20 minutes or so, under dash multimeter set to 20k ohms with red lead to red wire connect, black lead to each of the other pinouts. Ohms kept rising steadily past 18.99+, then to "1', OPEN CIRCUIT??? ANYTHING HERE, WITH THIS DATA?

Initially I checked the evap/ air pump circuitry, if I remember correctly a relay and "valve" cheapo plastic material, was replaced, the charcoal cannister, last week. Checked the check valve in the purge solenoid line, top of engine, membrane seemed fine, air in exited ok, reverse, no air passed. Seemed OK! So, still looking for the fault. Also, my GM MDI2 scanner/ diagnosis unit has failed at the worse time, presently. Using an Autel scanner, TOAD unit, currently>

Any and all input from you my Blazer familia would be most appreciated!

 

... The valves should be steel, not plastic, just what is on the front of the manifolds on your truck?

Also, that seems like the Retained accesory power circuit turning itself off, the diagram you tried to post did not render//

 

SMOG PUMP CHECKVALVES, no reference at all in my emanual for the car. Multimeter readings today! OK then?

 

Retained accessory power circuit turning itself off, so, nothing unusual there? Cannot find any reference to air pump smog, check valve except from the evap purge solenoid. Front of intake manifold sits the EGR valve!

 

CA emissions is just the K18 Smog/Electronic Reaction Air Pump which is located to the front passenger side of the engine bay underneath the core support. it runs two hoses from a vacuum controlled diverter valve to two large steel checkvalves on the front of each manifold, those valves keep the exhaust gases in and prevent them from backflowing into the rubber hoses and into the pump. EGR is standard equipment on all trucks both Federal and California emissions.

Anyways, what connector did you backprobe? that looks like the Datalink connector under the dashboard..

 

Thanks will check, manifold fronts for these valves and yes that is the data link, seemed a bit off there after I let the battery discharge. Does the ecu keep reserve power, a battery backup, capacitor or such? Sorry for all these questions, here! So glad to have someone to "bounce" all these things to. I say you cleaned those "spacers" at the check valve. Regards!

 

the majority of electronics in our trucks and any with some sort of computers in them have a metric ton of capacitors which depending on circuit will discharge their stored energy over varying rates. I have to ask why you were probing the DL Connector as this was initially a P0300 Chase, unless it was to check for voltage drop - as that is not how you test voltage drop
start the truck, take a multimeter and then connect one lead to battery positive, other to negative, note the voltage, then move negative lead to a frame ground, then a body ground, and note the net change between battery voltage when using battery ground, frame ground, and body ground, do NOT move the positive lead at all.

 

Attached my scanners, in a few minutes, drained battery to a no start. That's what made me suspect at the data link. measured voltage at battery, then to frame, before. No apparent change. Bought a check valve, install tomorrow. Will post results.

 

.. i did not recommend that as a fix for this, just as extremely important preventative maintenance as they Will blow out and your only indication may be a faint rubber/plastic boiling smell, so its not a waste of money but not what will nail this weird code issue in the head.
Is English your first language? im not ragging on you for anything but the way you do your sentence structure and the way you take things said is sorta off in a way alot of my ESL friends were when they first picked up the language.


Basically, we have 3 things that we can look into, and they each bring their own diagnostic path.

Mechanical - Headgasket blown (do compression check if you have not already)
Vacuum related - (Rotted out vacuum lines, if truck is 4WD check the cable that runs down to the 4WD actuator underneath the battery tray, and cap off the vacuum hookups on the plenum during testing)
Electrical Related - Poor Grounds, Poor sensor Voltage or Sensor dataline voltage/signal
Im still leaning heavily on it being either vacuum or electrical, you mentioned you replaced the spider, did you replace the upper intake manifold gaskets? once they get so old they no longer seal well despite being ""reuseable"", and what you may interpret as smooth running may be a bit more rough then you think, the motor should be literally, smooth as glass, being a V6 it will shake, but you should feel absolutely no tremble, just a steady vibration while inside the truck with your foot on the firewall or with a long extension pressed up against the side of the block or cylinder head/valve cover

 

American, born and raised.......Valve job done, no vacuum line leaks, new (head) gaskets after 3 smoke tests no hint of smoke leaks anywhere. As before, engine runs very smooth, no hint of misses from idle through just before redline. This is my first California car and whole emissions thing, here, new to me. Layout of your engine bay different than mine. From above pictures, what did you circle in blue? Thanks again!