VIN "X", as far as vent solenoid circuitry, is the same. The orange wire however, should ONLY show battery voltage when the ignition is in the RUN & START positions. The orange wire connects to the underside of the underhood fuse block, (connector 3 pin F2) and it runs directly to the vent solenoid with no other connectors in between.

Something to check: The pink wire at the purge solenoid on the passenger side of the intake, near the ignition coil, is also fed by the same fuse. If your orange wire has voltage all the time, the pink wire should too, as they are connected together inside the fuse panel.

 

Found pin 45 (confirmed by looking at the back of the VCM connector and finding the white wire) and it's about 250 K ohms between there and the solenoid connector. Yikes.

So obviously I'm going to run a new wire. Patching in at the vent solenoid plug won't be hard, what I'm wondering is if somebody can clue me on how to remove the plastic back on the VCM harness connectors? It just looks like I'm one push too close to breaking some plastic catch as I try to get it off.

The other option is to solder my new wire (with heatshrink of course) to the white wire just before it goes into the VCM connector. Suppose I could go that way, but I'm still wondering how exactly to get the VCM connectors apart.

Thanks,
Chris

EDIT: Hey Captain, just saw your last post. Okay, I'll check for always-on voltage at that other wire.

 

250K ohms, there's your problem. Good job. The plastic thing just snaps off with some clips. Best to solder a new wire directly to the pin. Sometimes the factory crimp to the terminal captures insulation instead or copper wire! Soldering back of the pin won't do any good if the terminal isn't crimped to the original wire. Same program at the vent solenoid connector.

EDIT: 250K ohms is not an open circuit, but close. Probably just a poor connection.

 

Alright, I'll just wrestle with the plastic backing until I get it off. Or break something. Yeah, I also figured it would be better to solder directly to the pin.

On the orange/pink wire front, it gets stranger. I'm pretty sure I found the purge solenoid connector: two wire connector with one pink, one black wire. The pink wire behaves like it should - nothing with no key in the ignition, battery voltage with the key in Start or Run.

Just to be certain, I checked the orange wire at the vent solenoid and it's still just as it was before - always at battery voltage no matter where the key is.

Is this a very bad thing? Or just a mystery.

 

The pink purge solenoid wire is working correctly. The orange wire is shorted to battery voltage somewhere, which means it is not connected to the fuse panel where it belongs. Who knows if something else is messed up, probably is. Sombody else has been there before you The problem could be anywhere along that orange wire. The only issue is the orange wire has voltage all the time, who knows if it's fused or not.

 

The car was owned by US Fish and Wildlife before I got it a month ago at auction. I wonder if this problem was already cropping up and somebody half-fixed it, patching the orange wire to hot somewhere but not fixing the white wire. Hmm. So maybe I should run TWO new wires.

 

I'd say you hit the nail on the head there... somebody half fast fixed the orange wire and gave up trying to find the problem with the white wire. You can track it down and find the problem, or run new wires, your choice.

 

Well, I tracked the orange wire in the loom all the way to the fuse box and couldn't see where it had been messed with (although I didn't do continuity tests all along sticking a pin in the wire). It may have been moved right underneath the under-hood fuse box, but I didn't want to take that box out just to find out.

I tracked the white wire from the solenoid connector for about 3 feet, then lost it around the gas tank - it went to a different loom than the one that takes the orange wire to the front of the car.

So, because I wanted to simply solve my SES light problem, I ran a new white wire and now everything is good. Thanks again Captain for the pinout info I needed on the VCM harness...without that this would have been a much longer day.

Thanks,
Chris

 

I haven't had even the slightest amount of time to really dig into the solenoid issue I might have to bite the bullet and just bring it in. I did however just buy a k&N drop in and hopefully tomorrow before the Bears game I'll be able to do the plugs and wires so maybe I'll see some type of return on the money spent. I have to say though if I can't squeeze 20's out of the blazer before snow fall i'm going to be looking for something else like a subaru or something , I just can't afford to drive it at this rate if a motor this size wont give me 20's but my 99 Tahoe with the 5.7L used to give me 20-24mpg on the highway depending on trip length and 15-17 city .

Chi_Town

 

bump!