Ok, I found out what that little black and green wire does: it goes over to the engine light on the dashboard. My engine light stayed on since August, but I've been real busy and haven't had time to mess with it. And then I got laid off, so money's been tight. I wasn't driving the truck much before I lost my job because I was working from home. But now I need it to do cable work for local 1099 jobs I'm getting while I look for work.

Anyway, the tuck saga continues: because of that little black and green wire, I don't know what codes my engine is throwing. Finally went through a couple tanks of gas -I'm now getting worse mileage than ever: like 6 mpg. Truck runs nice and strong, but I'm blowing black smoke - I didn't know it before because you can only see it at night when someone's close behind you with lights on.

I went ahead and did the battery test on the ECU to see if maybe some of my splices were no good (less than 12v, according to the manual). I found out that I still have some issues - one of them was on the AFM, which was only getting 7v. But when I traced the wire - it was one that I had already replaced! So what's up with that? I went ahead and cut out the wiring and spliced in a new wire - but it didn't change a thing! Still only getting 7v. And the plug for the AFM is new. Also, the AFM is new. I don't know if I mentioned this, but I now have a spare ECU. I plugged the spare one in and guess what? Still 7v. So what on earth could be the problem? the plug going into the ECU? I sprayed it with dielectric grease cleaner or whatever the auto parts store gave me, but no change.

I tested my heated oxygen sensor as well - sometimes if I push my leads in just right, I can get 10.5v to show up on the battery test, but mostly it just sits at 6.4v. And yes, it's a new O2 sensor. The black wire that goes to it seems to be part of a dual-core wire - looks like a mini cable tv coax wire because it's got sort of a mesh wire around a core wire - both are separated by the insulation - not sure where I get a replacement for that or what it would be called, but anyway, I left it in place and routed around it with a piece of test wire just to see if providing a secondary known good path to the sensor might help bump the voltage up , but no, it did nothing.

I'm wondering if this battery load test recommended by the manual is good for anything at all because it certainly hasn't given me any help troubleshooting.

So I'm stuck - it's not the wiring, apparently, and it's not the sensors, and it's not the ECU. bout ready to just sell the sucker, except I need it for work now. Any ideas?

 

I set the timing today - it was around 7 degrees, so I bumped it up to 10 or 11. need to test drive it.

I sprayed some cleaner around the air intake to just to see if I had any leaks, but detected none.

 

Gota be frustrating I know. Been 'there'. I'm not convinced it is not your actual wiring yet myself. Odds of two ECMs being faulty I think is a bit of a stretch. But, not impossible. On third gens, from different resources you can see that many of the inputs are actually op amps and pullup resistors, so on inside. I recall when I built my harness (parts anyway) it turned out I had an issue with ONE ground on the ECM that the CORelay 'gounded' to. Altho I don't recall right now how I cured that, it was the problem.

Good luck. You will get it.

 

ok, this gives me a direction, at least -

so a bad ground on the ECM? I've been suspicious of the CORelay from the beginning, but it seems to check out - maybe I need to check the ground for it....just one more time...

the weird thing is that some of the pins on the ECM are showing 12v, and some are not. So it seems like it could be a problem on the ground for whatever sensor is in question itself, maybe? I guess I should check.....

 

The best $50 you'll spend this year.
It's NOT just diagrams like you see in repair manuals. It HAS a TON of data, specs, etc.
I can't overstate just how much it has.
Very fair price, considering what you'll be getting.
eBay 1994 Truck EWD

 

Yeah. What Jimkola said. The 'pin-out' and connector diagrams are a MUST. I could NOT have done my swap without this. I also put a R150 from a 94 into my 95 auto. And I paid some $100 bux plus for it, a decade ago. (Voluntarily. There is no inflation. Don't swat me.) What I wished I could have also done is buy same for the wrecked 99 I got my motor from. That and able to have redrawn the schematics to reflect all the changes and additions I made. Already had to figure out whatinblueblazes did I do, esp with my rear fuse panel.

 

ok, thanks guys -
I have the pinout diagram (I think I put a photo in the thread above previously). I've spliced in new wiring for the suspected bad wiring - where my battery load test indicated less than 12v was getting to whatever pin I was testing at the ECU - but this still left me with voltages below 12v.

So today, I went back and started over - most of my new wiring is testing good. But the middle plug on the ECU - the smallest one - has some pins that are consistently testing less than 12v - one was only 1.2v, the others were like 6v, 7v, 3v, etc. So I sprayed some dielectric connector cleaner on the that plug and retested, and the voltage jumped on one of them from 1.2v to 7.2v. Maybe I'm onto something?

Does anyone have a link to the exact pins I would need to replace the existing pins ? I'm thinking I should un-pin each wire from the plug and put a new connector pin on it. I found this: but will it have the right pins on it? Anyone done this before? tips/advice?

I'm getting 6 mpg. lol.

 

here's the pin:

 

ok, finally had a whole day to look at this.
I bought some purple wire (400' marine grade), and a bunch of connectors, but before I started ripping things apart, I did one more test on the ECM on one pin that was getting 7v. Then I unplugged and just did pin to pin across the computer - and it was still 7v. Something wasn't adding up.

So I did a search and found a link to the entire shop manual http://repair manual. free. fr/_manuel_ moteur_22RE_ 3VZE.pdf (put spaces in it so the bots don't delete it). Turns out that page with all the pinouts? is only the first page of that part of the manual. So the idea that each pin should have 12v going to it isn't right. On page 2 (and for 30 pages after that), they describe what the voltages should be. When I first found that page on the rockauto website (under the ECM section), I showed that page to my mechanic buddy, and he was like, "I dunno....an o2 sensor probably doesn't have 12v going to it all the time...." shornuff.... he's right.

Anyway, I'm going through testing the ECM, step by step. it's going to take a few days, but I'm annotating my shop manual with the test results. I already found that the new AFM I threw on there had 0v across vs2 and e2 when it should've had 4-5v. I put the old AFM on there - and it is testing better. Still need to do the rest of the test on the AFM before I test drive it, but maybe there's something to it...

 

This is more for me than anyone else, just want to document stuff...

Right now, I'm still getting CEL. I have limited power doing this test:
I start the truck, and drive 1/4 mile down the road to a highway. I pull out onto the highway and try to get up to 65 before the engine starts to warm up, which I can do pretty easily. It's all flat ground. I get the truck up to 70 or so, and then as soon as the temperature gauge starts to rise, I start to lose power. After about a minute of this, I can't even keep it at 55 in 4th gear, so I turn around and chug home. So I've been going through the factory manual, testing everything in the little troubleshooting matrix on page 289.

1. My COR failed the factory test, so I replaced it. Still performs the same on the test above.
2. The AFM - the original AFM - is testing the best, so I have that one installed.
3. There's not a good test for the fuel pressure regulator FPR that I can find, other than "symptoms to look for", of which I have all of them (running rich, hesitation during acceleration, fuel smell). So I ordered a new one. The current one is 2 years old.
4. I've been avoiding testing the O2 sensor, since the test is 2 pages long. But I didn't have anything else to do today, so I went and did the first test - the resistance test - should be like 5.1 - 6? ohms? Mine was 22,000 ohms. So I get to replace it rather than doing the rest of the tests, yay me. But same thing as the pressure regulator: I replaced it just 2 years ago. so...?

My gas tank was professionally cleaned and poly'd right around the same time - 2 years ago. And I replaced the fuel lines and filter and spark plugs at the same time. about 1.5 years ago, I replaced the injectors. Maybe 3 years ago, I did the plug wires. I wonder if I got a bad aftermarket FPR, and then running rich ruined the o2 sensor and other stuff?

Anyway, mail is slow this time of year, so I'll provide an update after I get the new pressure regulator and O2 sensor installed.