Ok, here is the latest news. The 10 amp fuse in slot "ECM-B" blows frequently. I have replaced is several times, so far it hasnt been much of a problem, but worry about it going while in traffic, as the car immediately dies after the fuse is blown. Its seems to happen when I hit a bump or when Im just starting to move from a stopped position.

First of all, what does ECM-B do, (as opposed to ECM-A) I know what an ECM is lol! but what does it do specifically and is this a result of a poor ground possibly or something deeper? The car has countless electrical gremlins, which I have opted to ignore unnecessary issues (dome lights, front turn signals will work sometimes and sometimes only one will work, then sometimes none will work, etc). But I cant have the car die on me and cause an accident of course. For a while the check engine light was on throwing "trouble code 43", I had recently replaced the ignition coil and after a month of rough riding with check engine light on, it seems to have decided run right. go figure.

 

ECM (engine control modual) its the brain box for your system.

If you are having intermit electrical issues, this falls under shorts and possibly fire if you dont get these things fixed.

I replaced a whole dash wire harness on one last week due to too many wires were brown out or fried due to some back yard splices. They would have for sure ended up toasted with a nice fire if it was not done.

Your short might be in the colum due to the signal issues. Might have a hot wire that has a bare spot on it or loose and when it gets jared it causes a spike. Hence why the fuse blows. I am sure within a day or less someone can help post or send you the dash wire diagram to help traces the issue.

 

I know that, let me rephrase. Why does the ECM have 2 fuses? Does one do something and the other do something else?

I may actually enjoy watching that.
My Blazer has plenty of those. I have ghost wires that lead to nowhere under the dash. I know theyre aftermarket. My blazer is my beater so I really dont care to put unnecessary work into it but there are some things even I won't half-***, but Ive found a lot of questionable things. As far as I can tell, the previous owner had a stereo and amplifier at one point and maybe fog lights and God knows what else. The stereo wiring was a fire waiting to happen thats for sure. I replaced the constant battery and the speaker wires and Im still having hiccups in the electrical system itself. The engine in that car is the only thing thats really worth something, 4 years old not even 10k miles on it, and its bored out and stuff.

Is a wiring harness something I can get new or do I have to yank one from a yard?

 

bump

 

You can get about all the connections new, but the price is quite HIGH. A donnor from a bone yard would be more cost effective if you have the time to pull it. I don't let the yards pull them due to they love to just cut what they can not remove. Most of the time this ends you up with missing sections that you may need or massive broken clips.

 

Access your ECM, with the engine running take a screwdriver and tap the ECM with the handle. If the engine stalls, replace the ECM, because you probably have a cracked circuit board in the ECM.

 

ECM has a bad circuit? That would make sense considering the Trouble code it was throwing at one point said something about Spark control module and ECM. But the light has gone off on its own after about 3 weeks or so. The odd thing is, it only seems to cut out like that when Im either going from a dead stop or if Im climbing a hill and hitting a bump (I deliver newspapers on some rough roads). But Ive jumped rail road tracks in it and gotten literally a foot and a half off the ground without having the fuse blow. Seems to only happen when its pitch black outside too (the worst time, not only for my personal safety but I can never seem to find a fricking flashlight to swap the fuse.

 

What kind of work and pricing would I be looking at to convert this engine to carbureted? I think the original 4.3 blazers were? I've had just about all I can stand of this electronic Bull****. A junkyard wanted 100 for wiring harness and 40 for a new PCM. And its non-refundable, and they wont do yank it until after the new year. Now the Blazer wont start at all, the fuse blows immediately as opposed to being sporadic. The truck is worthless to me right now, and it will find itself in a crusher if it continues to agitate me.

 

Disconnect the connectors to the ECM and replace the fuse, then turn the key to the"run" (not "crank") if the fuse doesn't blow with the ECM disconnected, you probably have an internal problem in the ECM.
You should be able to get a remanufactured ECM from your local parts store for under $100

 

I thank you guys for putting up with me. I'm looking at a new wiring harness on Ebay, they want 225 bucks to "buy it now". I bid on it instead, Im winning apparently but the "reserve is not met". I emailed them told them I'm not going higher than 150 for a damn bundle of cables and a fuse block. How much would I be looking at for a brand new one? You said it was "quite high", is 225 what you had in mind Hawk?

Im going to get an ECM from a yard, theres a place in the area that is highly reputable, but the guy has pretty much expressed no desire to fiddle with the wiring harness. (its not a "self-service" junkyard). He wants 100 dollars for the harness and 40 for the ECM. At the price for the Harness, I may as well go new for that.