As stated in the title I have a 1995 4.3L Vortec Vin 'W'.

Here is the story, I was leaking coolant from the back of the engine so I replaced the lower intake manifold gasket. From the time I stopped driving the blazer until I finished the job was about 3 weeks. After getting everything all back together it wouldn't start. After much effort I ended up towing it to a shop to have it looked at. They told me that it needed a new battery and that the computer was bad. My questions are what could have damaged the computer as not to do it again? Is replacement of the computer something that you can do yourself assuming it is programmed correctly for the vehicle? When I say computer I am referring to what I understand to be the PCM which is under the hood above the shock tower on the passenger side.

In addition the blazer still leaks and the story on that was that it is leaking from a freeze plug on the back of the motor. However some threads state there are no freeze plugs on the rear of the engine while others state there is. Is it possible for a 95 blazer 4.3L Vortec to have some kind of plug on the back of the engine that would leak coolant?

Any help is appreciated thanks.

 

Is the computer in the engine compartment or under the dash. If it's in the engine compartment on the passenger side, it's easy. Can't say about the OBDI in the dash. As long as you find another with a similar engine the computer will be the same. Just make sure it's the same year and the ODBII in the engine compartment, not the OBD1 in the dash. If you find one at the junk yard get the warranty.

 

The computer is in the engine compartment. There is a seller on ebay that states they can program it to be for the right vehicle with a one year warranty. So it is really as easy as just plugging the new one in? Do I have to deal with passlock when installing the new one?

 

It needs to be programmed with your specific options on the vehicle. You can see if the dealer would allow you to buy a replacement and have them program it properly.

And you will have to do a security relearn as well as a CASE relearn. You could probably do the security relearn in your driveway, but the CASE relearn (aka crankshaft variation learn procedure) will require a full feature scan tool capable of bi-directional control.

 

The chance of saving some big time bucks and doing this myself are dwindling. Would it still start/run (potentially poorly) without a CASE relearn?

UPDATE:
I had someone else look at it and they came to the same conclusion, so I replaced the PCM to only find that it still wouldn't start. Had another person look at it to find the scanner still couldn't pull codes. After this I had a light bulb go off and realized I had a very hard time plugging the crankshaft sensor connector in. I pulled the connector and checked the sensor to find of the pins bent flat against the inside of the sensor. I straightened the pin and hooked it back up and finally it would start! I put back my old PCM and it still starts and runs. This bent pin explains why I could get not spark and a scanner couldn't pull codes. Amazing what one little pin can do. Thanks for the help. Hopefully someone else can learn from my mistake.