Hello, I have decided to post this issue here aswell in hopes that more eyes might catch it and be able to help out. It has been posted in the electrical section since it does involve possible wiring/ electrical issues but it has a combination of related topics. Rest assured, this will be the only other section I post this in though.

Vehicle info:
Year: 2003
Make: Chevrolet
Model: Blazer Extreme
Motor: 4.3L Vortec 6Cyl
Transmission: Automatic
Milage: 103,918
Recent Problems:

1. P0200- Injector Circuit Malfunction along with P0302- Cylinder #2 Misfire......This is the biggest issue I'm concerned with. I came home from work one morning and SES light came on as I'm driving 20 mph in a school zone. I park the truck turn it off and grab my scan tool to read the codes and clear them. Turn it back on after clearing and nothing. Find out ECM1 15 amp fuse blown. Plug another one in, try to turn the truck on...it blows. Yesterday I unplug the Injector wire connecter and plug another fuse in and voila no blown fuse when I turn the key on. So I have since then removed the spade connectors to injector #2. I taped the #2 wires off and plugged the remaining wires in to their home. The truck runs finally. Here is where I need some help. I have looked as best as I can see over and under for burnt or cut wires.....nothing found.
2. Intermittent lean codes that sometime go away on their own, more random misfires (goes away for a while when I clear the codes aswell)
3. Intermittent rough running/ idle upon startup either after sitting over night or a quick walk through walmart for groceries (goes away for a while when I clear the codes aswell). Also, the rough idle will also go away if I turn the truck off and back on sometimes.
4. Brake trouble code (scan tool does not see the problem)

I am wondering what the liklihood is of:

1. Just a bad spider injector
2. Some hidden short to ground
3. Or a bad PCM.

Any other suggestions of where to check?
Could 1-4 all be related to a bad PCM/ Wiring?
Where are some known common areas outside of the wire harness along the exhaust manifold that causes these type of issues?
As mentioned above I have seen no burnt or chaffed/cut wires (outside of tearing out the whole wire harness to check)

What has been fixed since being in posession of it:

1. Exhaust- Caused by clogged catalytic converters
2. ABS Module- Caused by ABS light to come on
3. Plugs, Wires, Distributor Cap and Rotor- Caused by misfires and continued white smoke to blow out of new exhaust (no longer blows white smoke).
4. Vacume line running from motor to vaccume canister inside drivers fender- caused by sight of deteriorating hoses.

So far, that's the gist of what I've encountered and fixed.

I am still digging around the forum to find an exact replica of symptoms along with a fix that I am facing but so far little here from one person and a little there from another person with little response of the OPs on a fix or anything. Rest assured I will confirm my fix once its achieved.

For me all signs are pointing to a bad PCM which is possibly also causing what I believe to be a ghost brake trouble code although, I did smell brake fluid one morning but fluid looks clean and full with no drips or wet spots associated with brake system.

Any and all help is greatly appreciated and I do plan on returning the favor by contributing to this forum aswell (As much as I'm sure you've all heard this. I honestly mean it!).

Thanks again Everyone, P.S. Once again, Sorry for the long post....

 

I had this same problem myself P0200/P003x. Look for burnt wiring harness at the front of the passenger side exhaust manifold grounding on the manifold somewhere (look at bottom of the harness for melting). Injectors are powered 12V and then controlled by grounding through the ECM. I had replaced my engine and did not route the wiring harness correctly. You have a problem in the wire that runs from the PCM to #2 injector.

Good luck

 

Ok thank you very much for your help I will double check the wires here in a little bit and report my findings!

 

Upon further review of the attachments, in your case (blown ECM1 fuse) I think it is more likely you have a wire on the hot side of the injectors (ckt 439) grounding somewhere. Same wiring loom problem as these wires run side by side. Same P0200.

For ABS, a lot of inexpensive scan tools will not read the codes. I know that Car Diagnostic Pro for Android (using "Scan all Faults") will scan the other systems on your Blazer such as ABS, SIR, HVAC, etc. Costs $10 + Bluetooth OBD2 adapter to connect it (Amazon). It will also read Cam Sensor Retard, something important to have close to zero on our Blazers for optimal performance. Otherwise spark can jump to wrong terminal inside distributor and cause erratic misfires. What scan tool are you using?

 

Ok so quick update...upon further review of the wires after taking the casing completely off and tracing the wires to their endpoints. I can confirm it is not the wires.

Note: The pulled wires in the pics are the ones in question leading to the injector #2.












The only other possibility it could be is either the Injector coil on injector 2, or something with the pcm (which I doubt to be the case).
Guess its time to get ready to replace the spider living in the motor.

As for the scanner that I'm using it's the zurich ZR15s From Harbor Freight. I will check out that app that you suggested.

 

Looks like you have thoroughly inspected the wires. I agree completely! Spider first suspect. Good luck!

Have you checked resistance of the injectors at the connector on top of the intake? That might be revealing.

 

Well I checked them prior to getting into the wires but I'm not sure if I was getting an accurate reading. I've never been good with ohms. But I think my multimeter might be defective because I was getting resistance on each injector starting at 14-17 ohms then as I'd hold it there it would drop to about 7 and I'd get frustrated thinking it wasn't accurate and move on to the next one. Perhaps I'm missing something though. I'm going to relearn resistance reading though and try again. Perhaps buy another multimeter just to be sure.

Quick question, do I measure resistance with the connector plugged in through back probing or unplugged directly on the injector pins? I tested it with the connector unplugged on the injector pins themselves and that's how I got my reading.

 

I have a fairly new AC Delco spider sitting on my shelf and I just tested it - about 12-13 ohms steady across each set of terminals in the big connector that sits under the plastic part of the intake.

 

I wander what I'm experiencing then. Your speaking on the connector location where the big harness plugs into correct? I have yet to begin to take the intake cover off that exposes each individual injector. So if it's under that I'll have to get to that tomorrow or Thursday. Mind you although I've been doing my research and learning how it's done I've never done these type of injectors before so it's all new to me. Seems pretty straight forward though.

 

Yes, no need to remove the intake plenum. Just take the connector off the intake manifold and measure across each of the 6 pairs of terminals.