like I said - I pulled out the harness from the ECU and dragged it into the engine bay so I could easily test every wire end to end - started with the AFM - all good. Moved to the TPS - the housing on the plug (the wire side, not the unit - the unit is brand new) is all shot to crap. I had already bought a new plug, so I spliced it into place yesterday. But the TPS wiring is all good (continuity test).

When I got to the speed sensor - the wiring is failing the continuity test, so that's where I'm at - and found out there are 2 speed sensors, even though my truck is manual (not AT). Anyway, going to try and figure out where the wires all go for the speed sensor- they don't seem to match the ECU pinout I printed out for my truck, so is the wiring no good, or am I just testing at the wrong place on the ECU? Hard to separate those wires, as they are really stuck in there on the frame - hard to reach, and really greasy. I have my suspicions the speed sensor might be my problem, but unable to prove it at the moment. so I'll keep plugging away at it.

I mean, would a faulty VSS1 speed sensor cause the vehicle to stay in "limp mode"? dunno....

 

The other part # I said looked good is for an automatic. Since you have a manual, go to the online parts catalog, select the frame code and characteristics that match your truck, to find the right part #. I've not had any problem finding the correct part # as long as I'm using the right frame code, etc.

For example, here I selected frame code VZN131, char VZN131L-RKMGEK. Just click the frame code box, which will clear it, then select the right code.

https://www.japan-parts.eu/toyota/us...meter/4#83181A

 

Ok, I went through that - punched in my vin - and..... they don't seem to have the 2-pin speed sensor as a part for my vehicle. But I definitely have both, and my truck is a manual / stick, not an automatic. so I don't get it.

the wiring harness looks factory - I really don't think someone came in there and redid anything. I believe I'm only the second owner on this truck. Plus, the wiring colors match the haynes manual....they just don't go where the pinout says they should.

So if someone wants to chime in on this: I'm looking for a replacement plug (not the sensor itself - the plug from the wiring harness - one I can splice into the existing wiring) for the VSS1 speed sensor - the two prong sensor. where / how would I find that?

 

Can you post a pic of the sensor you're talking about, in-place?

I put a 94 r150 into my 95 (formerly auto) with engine swap to 3.4.
Being a bit daft, I can not picture in my smol brain which you're talking about.

My experience; 95auto had a physical spinny-cable that attached to the back of the cluster. Went up thru floor board near accel pedal. There was attached the A/D converter.
The 94 manual, had a (hall-effect) generator - also with a plastic wheel gizmo spun by a gearing on the output shaft. Part of the tail housing assembly.
This is a then signal that goes up to the matching cluster. A 3-wire plug. The 94 (manual) and the 95 Auto have different clusters. My guess also is that the cluster then sends a speed-signal over to the ECM.

 

Alrighty, y'all asked for photos, here you go:

My big question is: where do I get a new plug for the VSS1 (? is that the right name for it?). It has no continuity back to the the passenger kick plate.

3 plugs for the ECU (circled), and the white one (doesn't plug into the ECU)

This is where the white plug goes - passenger side kick plate, above (or in front of?) the ECU

Got the wires all hanging out here.

This is where the 2-prong VSS1 (?) plugs into.

This is the plug itself.

Should it look this ugly? Where can I get a new one of these?

yup. that's her. " lil' red "

 

Oh...
and 10 years ago(?) I was trying to replace the starter, and couldn't get it past all the wires that went past it(including the speed sensors), so I just cut them all, then went back and spliced them all back together later and did my due-diligence and waterproofed all the connections. It's very possible that THIS is where the short is. I definitely have a short because I put my continuity clip on the plug (red/white wire) in these pics and traced both wires by hand back to the plug - colors match and everything - and I get no tone at the other end (no continuity). I even used my old phone company tone generator and the little clips (they have and extremely sharp little pin pad that pierces the wire jacket and provides a good contact) - still nothing. It's definitely shot. Whether this no continuity situation puts the whole truck in "limp mode" ("9 mpg"), I don't know.

Oh, and the other wire (brown/black?) from this VSS1 plug? It splices into the brown wire from the VSS2 plug at the same connector pin (on that little white plug) as the VSS1 plug.

Now it ran fine for 10 years after that, just as an FYI.

 

****** update *******

I found something: I realized that the rest of the wiring that feeds the speed sensors ALSO feeds the O2 sensor. Since there's a short in the speed sensor wiring, there could also be a short in the o2 wiring, right?

So I toned each of them out - one of them (white /red) doesn't have continuity. I checked the others and they do, so I went back to the white red one - still no continuity. Ok, so now I think I'm getting somewhere.

 

So the greasy thing on the side of the transmission is the Reverse Gear Switch. It is busted. Inside the trans is a triangle / ramp shaped piece on the slider rail that contacts and closes that switch when put into R.
(Haven't looked at connectors in a while, but its just like the 4WD "engaged" contactor on the front diff.)
And IIRC there is a similar one up on Xfer case near shifter that tells computer you;re in 4W or 2W drive. I honestly do not recall if the connectors are same. (Note how similar plugs have slightly different tangs and/or holes so it is pretty hard to plug something on a Toyota into the wrong place.

Inside up above ('inside' to where your ECM mounted - those are IH-1 (eye-h one) and IH2, if i recall correctly. They connect cowl and other harnesses to engine harness, etc. These are the little buggers that cause much gnashing of teeth for engine family swaps. The White is the IH-2. Maybe if you still need later, I can dig up my '95' wiring EWD, if you have particular q's.

 

false alarm. I tested it again - in fact, I've now tested it 4 times - that wiring is solid. I don't know what was going on during that failed test. But today (the 4th time testing), I even jiggled the wiring (where I made the splices years ago) - and it's still solid - good continuity.

Today, I also tested the igniter wiring - it is also testing continuous.

Ok, so the only thing left to test is the vehicle speed sensor wiring. Maybe that's where I'll find the fault....

 

Ok, I'm doing the MFI test on the ECM / ECU for my truck - looks like my ECU is no good - am I doing this right:



After painstakingly tracing every wire for each sensor that was throwing a code, I made a small diagram and compared it against this one ^, and it seems to match pretty well (i traced my wiring correctly).
So I stuck my multimeter on there as described in this attached picture, and shornuf, I'm getting voltages less than 11 V on many of the pins where these sensors go - some are in the microvolts, others are like 7v or 9v. A few are 11, and some are 12. So.....

Bad ECU. Right? Is there anything else you would check before just buying a new ECU?

first time commentors: I already did a continuity test on the wiring for each sensor - all good.

 

Alrighty, another update:

found a cheap ECM with a 90 day warranty, plugged it in, and drove around the neighborhood. It sucked. at least I didn't smell fuel, but the idle was terrible and the check engine light was still on.

I did the same battery load test on the new ECM - and wrote down what I found. I won't bore you with the details, but every pin that had voltages in the millivolts on the old computer had the same voltages on the new computer. so it's not the computer.

Just for fun, I sprayed some dielectric grease on one of the plugs on the computer to see if the contacts were corroded -nope, same voltage results. So my wiring is no good? the ohm results were good - I have good continuity on all my wiring. But this battery load test.....I guess the wires aren't carrying the load very well.

I guess my question would be: how do you replace the wiring end to end, including the little pin inside the plug end of the ECM? is there a good method, or do I just cut it off close to the ECM plug and splice in a new wire?

thanks!

 

I think you're on the right track with the wiring myself. Totally unrelated, but had a job for a time, and the crew had this radiation source densometer. It supposedly worked with the same cable that a pressure transducer used. So folks would ohm that out, and see " well 2 ohms in 100' cable" thats fine. And it would be. But the densometer actually used a Frequency signal. And just because a cable would pass a voltage, did not mean it would pass a range of frequencies. Read where smart folx call that a 'frequency response'.

Just got my rebuild plated. Today in fact. I still have what I think is not-great idle responses. I had posted in the 3.4 swap forum about what Snap-On scanner reports the TPS signal the ECM sees. Is an 3-bit stairstep. The dealer mech (whom had also done a swap himself) said that the throttle body was bad. (even tho I had it rebuilt pre-emptively by MaxBore in 2020). But thing is, he was correct. I put the 'washer' mod on and that made it a ton better. Plus the afm had some sort of lint across the diode or capacitor what ever that little critter hidden in there is. Now its just sometimes very low; like in the 600s. Sort of annoying with the A/C on. BUt not complaining cuz I'm super stoaked and thankful the A/C even works. (I did the wiring adaption m'sef). And get 18 if I keep it at about 70ish.

SO I think that you may be hitting something 'similar'. Just because there is 'continuity', does not mean that whatever you target sensor signal is, will get passed .
Then again, we all got layed off during the Cough(tm) so there's that to my resume. I also eat crayons sometimes. So, not financial advice.

 

dielectric grease does not conduct electricity, you might want to clean off the ecu connectors as best you can.

one strand of wire might be enough to show continuity in the multimeter, but one strand probably won't be big enough to carry the full current load.

how much is a junkyard engine harness?

 

It's some kind of spray more than a grease - got it from Oreilley's.

The junkyard engine harnesses are hard to find around here - there's only 2 junkyards with any 4runners / pickups in them, and neither of them has had a 3.0 in years.

The online ones all have broken plugs or missing something, and they don't make new ones (that I can afford).

Anyway, I'd like to be sure I'm not just splicing in new wires only to find out it's the metal clip in the plug or something like that. be a PITA to end up with the same problem I already have.

Anyway, I'll check around online see what I can find, but if anyone has an idea, please share what you did...

 

Ok, started figuring out where each wire goes and what the voltage is...
You can see my test results here - notice the ones I circled are measuring in the "millivolt" range - the book says they should be 11V or more. Also, you see two tests for each wire - one with the old computer plugged in, and one with the new computer plugged in - so the problem stays put - it's in the wiring, not the computer. I think.


From the list above, I made a problem checklist, complete with wiring color, which plug and which wire it was (some of the slots are blank, so I'm only counting wires), then I cross-referenced with the book to say what the function of that wire is (helps me locate the other end):


Anyway, I started off with the injector wirnig - I cut it off a few inches above the ECM plug, and then traced it over to where it splits off into 3 wires (3 for the left side of the engine / 3 for the right side), and soldered in a brand new wire. Then I retested the voltage - and wow! now I'm getting 12V instead of 30mV!

Ok, so I'm onto something, I hope.....going to redo the rest on my list....might take a while....

 

what did the split look like? was the connection corroded, like what i posted for the 22re?

 

I don't know - I missed that picture.

But mine was slightly corroded. After more inspection of the injector wiring, I went ahead and ordered 6 new plugs. Going to rewire these while I'm at it. one of the wires coming of an injector plug is cracked, and the wire isn't very pliable. If I don't do this now, I'm sure I'll be doing it in 3-6 months. It's time to just solve all the problems and the potential problems.

 

i also replaced the injector plugs, and cut/stripped/resoldered the corroded wire junction... one of the big wires going back to the ecu appeared to be corroded a couple of feet long(!), i kept cutting it back then finally stopped to replace what was missing, shoulda replaced the entire length but it runs well now.

here is the corroded wire link that i posted to this thread back in june: https://forum.ih8mud.com/threads/a-2...-i-had.311436/

shrinkwrap the repaired junction with thick high quality shrink wrap that has internal adhesive on it, don't use the junk from harbor freight... here is some good self-fusing tape to wrap the harness up with: https://www.3m.com/3M/en_US/p/d/b00011950/

use a higher-wattage soldering iron, 20-25 watts.

 

I have a 1990 4Runner with 5sp manual, I have had for 30 years. At 308K miles, had the 3vze motor rebuilt. Also I have the Black/Orange shop manual I bought 30 years ago from the dealer. If you need parts, car-part.com is a salvage search place I have used. I have not messed with my orig Japan wiring. This company has some connectors auveco.com/carbrand/toyota/toyota

 

Ok....Let's not jinx ourselves here....but I just got done putting it all back together and covering up all the wiring harness with new sleeves and tape. Did a little run through the neighborhood and then out onto the highway just to warm it up and see how it runs - I think I could live with it at this point. I still have engine codes - the engine light is on, even after pulling the EFI relay for a few minutes - but maybe I didn't pull it for long enough. Anyway, I disconnected the battery and pulled the fuse just in case.

It did a lot better - a lot more power, no black smoke coming out of the exhaust - I might want to tune the timing a little bit more - I set it about a week ago when I still had wiring issues, so I'm going to take another look at it. anyway, it feels peppy. Like I said, engine light is still on, but never cleared from pulling the efi relay, so I'm going to let it sit and then check it again later and report back. Problem #10 in that image above is gnawing at me - it's a black and green wire that says "BATT" on the factory manual pinout for the ECM. When I traced it out, it comes out of the computer, then goes into a big gray connector inside the cabin (right kick panel), and then goes up behind the dashboard over to the instrument panel or somewhere. I did NOT want to tear into my air ducts to trace it. Anyone know what it does? Is it just reporting the battery level back to the instrument cluster? I hope it's not important cuz I don't want to fix it.

Got an exhaust leak at the back of the passenger head right where the port connects to the pipe (need a new o-ring, probably). I don't know if I have the patience for that right now - it's 101, and I'm in the south....so maybe that'll be a project for when the weather is in the 70's or 80's.