I've done a LOT of research here and other places on the web but...........still I have yet to find the answer. Please tell me if this PCM has the ability to be put into CKP relearn? I may have a few other issues but I did mess with the CPS and a complete distributor. After some harness checking I want to get this relearn done "IF" it is capable of this. I only have an ACTON 9145 and I've not seen anything in the scanner that would suggest it has that ability. As shown it is 16193495 PCM and it is only OBD1 certified. If someone had written definition files I could do it with TunerPro or EFILive. If it does.....I can find someone with a TECH-1A or TECH-2.

 

https://www.rockauto.com/en/moreinfo...029608&jsn=430

This may help a lot to start with. Nice, they have the 1995 manuals now.

Not sure about what you need to do. A bit more information may be required. Which Blazer? Guess from the part number is 1995. So year, best would be VIN decoded. Engine code? Injection type?

What exactly is your problem? What has been the error/fault/breakdown? What has been repaired/replaced?

It sounds to me as you had the ECU out of the truck. What are the numbers? Which chipset?

There are resources on the web with some even having mapped some GM ECU's.

 

Does your engine have a Crankshaft Position Sensor at the bottom of the plastic timing cover? OBD1 engines didn't have one so there is no need for or way to do a relearn on something that isn't there.
Here's a set of used service manuals for $120 less than the ones at Rockauto. ($23.97+shipping) instead of $148.95.
https://www.ebay.com/itm/1995-Chevro...9ZVOOF&vxp=mtr

 

Error_401.........in my research this PCM only came in the 1995 4.3 V6 CPI engine. Seems I have almost all the OBDII stuff but my sticker says OBDI Certified. Yes I have a CPS on the cover but I have not found that the OBDI certified PCM can or needs the CKP re-learn. This is why I'm asking here for information on this. Oldeerslayer...I have that manual but in it it keeps referring to this as OBDII which it is not. I was going to change the cover and sensor but didn't see any way to get the cover off without major work so I left it alone. I'm into this vehicle for lots of $$$$ in the transmission alone so I not willing to scrap it..........just yet. I guess I'll keep plugging away at the troubleshooting the sensors and what-not.

 

If it were mine I'd find a Tech2 and try to do the Crank Re-learn. I have one and have done it on newer trucks. The one problem with it is that it doesn't say anything like "re-learn complete". You just have to assume it did it.
From the research that I've done it appears that the 95 uses the same 16 pin connector as OBD2, but uses pins 5 and 9 to read OBD1 codes. 1995 GM vehicles are a clusterflock. I also see that CKP relearn is supposedly only needed on 96 up vehicles. No mention of 95's.

Do you have this book?
https://www.ebay.com/itm/1995-Chevy-GMC-S-T-S-10-Truck-OBD-II-Service-Manual-Supplement/222618267121?hash=item33d5152df1:g:T5IAAOSwrblZmIk k&vxp=mtr

 

Then it is one of the "oddballs" in the transition from OBDI into OBDII.

Maybe a GM dealer can help or does somebody on the forum have some insights?

IMHO it will depend on the PCM and if it is happy with the inputs.
Try looking for the particular numbers which should be on the case of the PCM.
They indicate the part number of the PCM and there should be other numbers indicating the chipset.
You may be able to find something on the net.

In any case - good luck!