SEFI Cars Auto To Manual Swap & That Damned O2 Sensor Plug

[ZephyrEFI]

Okay, so I'm pretty sure there's no dedicated thread about this yet, but I've seen it discussed in several other places. Today, I went through ECU pinouts for both '88-91 and '91-93 to make sure that now that I have swapped the 1993 Cobra computer into my 1990 automatic harness, there aren't any conflicts there. I found the pinouts here. http://www.veryuseful.com/mustang/tech/engine/

Anyway, I even made a spreadsheet comparing the two. The wire colors changed a lot, but the functions seem to all be the same.



Next we come to the O2 sensor harness question. I've found elsewhere here that you need to move the jumper wire on your O2 sensor harness from one circuit to another when you swap from automatic to manual. This hadn't been an issue for me before now since I had been using the A9P automatic computer. But now that I have the Cobra computer, it needs to be addressed. Mine seems to be the same as this





The jumper is currently going to the White/Purple circuit which.... I don't know what that does, but it's where you put it for an auto. So I guess I need to move it to the Light Blue/Yellow circuit which is the connection between the neutral safety switch/clutch pedal switch circuit and the ECU (I think, given all the wire color changes). I can't imagine what that has to do with the O2 sensors, or how it connected to the ECU before now without that jumpered, but... whatever, I guess. Anyone know?

I do notice though that both the NSS and the clutch pedal switch are looking for the switch to be CLOSED when the car is in neutral or the clutch is in so that the engine can be started. I'm guessing the programming for what to do with that information must just be in the ECU itself.

Any input? Am I on the right track? Thanks!

[erratic50]

Seem like the right track. I found all this info and documented it somewhere back when I was looking at using an A9P in my car but I got my hands on an A9L so I never had to do anything here.

[xctasy]

Yep.The jumper wire needs to be fitted. The semantics in the literature say the wiring is the same between auto and manual O2 sensor...the wire allows the auto to function correctly with a manual computer.

[ZephyrEFI]

the wire allows the auto to function correctly with a manual computer.

Wait, what? I thought that was a no-no. Swapping in an auto but still using the manual computer? But you could do the opposite, run a manual with an auto computer.

[4eyedblind]

The EEC4 doesn't care what transmission is behind it. Were you to use a manual comp with an auto trans, it might occasionally stall out as it approaches idle on the over run because of the idle load of the torque converter and the lack of a kick up feature in the manual comp. However, O2 wire switching has to be done if you use a manual trans comp on a harness set up for auto. It'll likely fry the pin 46 trace.

[ZephyrEFI]

O2 wire switching has to be done if you use a manual trans comp on a harness set up for auto. It'll likely fry the pin 46 trace.

So, it DOES have something to do with the O2 sensors then. Do you know what the White/Purple and Light Blue/Yellow wires do?

[NAVYCAT]

Im still thinking about my O2 connector, I passed smog but still cant stop thinking about those wires..... I have the manual connector

[ZephyrEFI]

Im still thinking about my O2 connector, I passed smog but still cant stop thinking about those wires..... I have the manual connector

Yeah, you'll prolly want to do that then.

I moved mine today. You can see the hole from where it was before, and i poked a (messy) hole for the new one to go through. My battery was very dead, so I didn't get the chance to try anything. It did seem to run fine with the Cobra computer and jumper in the Auto location the few times I was able to drive it last fall. I dunno.

[ZephyrEFI]

I tried to do a little more digging on what those wires actually do, the white with purple and the light blue with yellow. According to my 1988 EVTM (which as we've seen could be totally wrong for a 1990 harness), the light blue with yellow goes to a Neutral Start Switch. What's that? Is it different from the Neutral Drive Switch? Or the Neutral Safety Switch? I don't know! This EVTM shows BOTH a Neutral Start Switch, AND a Neutral Drive Switch on the EEC page. And they both go to Pin 30. I'm assuming one is auto and the other is manual, but the EVTM doesn't say on this page.

Further complicating things, according to the diagram I found and my observance of my harness, the O2 harness has a white with pink that is for the low oil sensor, but the EVTM shows that the circuit for the Neutral Drive Switch is ALSO white with pink. REALLY?! On the Start/Ignition page, it shows that the circuit for the Neutral Start Switch, which it does mention is for the Auto, OR the Clutch Safety Switch should be white with pink. It does not mention a Neutral Drive Switch, nor a light blue with yellow circuit.

The Instrument Cluster page has the Low Oil Warning Switch having a white with pink wire going to the Low Oil Warning Relay and from there to Start at the ignition switch with a splice to also go to the switches mentioned on the Start/Ignition page.

Further FURTHER complicating things, the harness I have for my T-5 does not even go to the Neutral whatever switch on the trans, it is jumpered red with light blue.

So, I am confused. I guess both the Low Oil switch AND the jumper affect whether or not it will allow the car to start, but completely separately, but using some of the same wires... ? Somehow... ? Elsewhere... ?

[NAVYCAT]

the connector where the O2 harness plugs into the engine harness, does it go over to the connectors near the master cylinder that then goes into the dash harness??????? I know im f-ing my brain over this. lol

[xctasy]

NAVYCAT, and Brad-Onator.

Any way the wind blows...

Because Ford has model year carrier breaks in its inventory supply, the wiring colors change, AIR got eliminated, and ABS and TFi module changed, the IAC, and Air bag functions form a new body computer happened, and at various times in the supply, Ford decides to regroup the wiring.

The Upstream 02 sensors never changed from 86 to 95. The OBDII cars were EECV, and they have Up and down stream O2 sensors, but even before 1996, Ford had to roll out some key changes to cover O2 function. So the color code and loop wire were running changes.

The Lincoln LSC stayed Speed Density till its demise in 1992,
and it was activated PID's
and because the later EECIV has activated PID's,

Ford changed the wiring protocols.

It has no 8 wire jumpered harness after 1988. It goes to a 5 wire harness.

Activated PID's is real time data display, removing the need for the old Breakoput Box so you can check the sensors on the fly with a normal pre ODBII reader to the six pin DTC plug.

For your TFi, Joe, you have a later system with Black CCS module, and that mixed in AIR, Air Bag and ABS stuff from your SN95. So the connectors are hard to work through.

Remember this?

Looking for a 88-90 O2 sensor harness for a T-5 and that has the pink/yellow jumper wire

I found one yesterday, but the O2 connector on one end is missing. I will try looking thru a couple more boxes of stuff and see what I can find.

For you, Brad, your system keeps the earlier Grey module, and should use the earlier color codes, but as you've seen, it doesn't matter much.



Y'all have been here before.

See Dean_T's last page

http://vb.foureyedpride.com/showthre...truction/page5


Now. here is the kicker gentlemen.
https://www.stangnet.com/mustang-for...umbers.565004/

https://www.stangnet.com/mustang-for...estion.884039/

....... That's how the Speed Density 02 harness is supposed to be.
On the mass air cars, Ford didn't run the additional circuits through the 02 harness like they did on the mass air cars.
The Speed Density wiring completely bypass's the 02 wiring and goes straight to the ECM.
So both manual and auto SD cars use the same wiring layout.
That's why there is no loop in the 02 harness.

But.....

At some point in 1988, ford did start wiring the Speed Density cars the same as the MAF cars. My car is a late 1988 speed density car, but with an 8-wire O2 harness with the jumper present. Early 1988's do come with the 5-wire o2 harness, so the change was made at some point during the 1988 model year across the board for all cars, speed density or CA mass air cars

Que Bohemian Rhapsody.

Nothing really matters, anyone can see
Nothing really matters
Nothing really matters to me
Any way the wind blows

[ZephyrEFI]

the connector where the O2 harness plugs into the engine harness, does it go over to the connectors near the master cylinder that then goes into the dash harness??????? I know im f-ing my brain over this. lol

You and me both. According to the '88 EVTM I have, it does, but I couldn't say about the later ones. It shows the connector there at left cowl, but doesn't show the one below the intake tube that all the pictures above are of. It doesn't show that one at all. So, take from that what you will, I guess.

Did some more poking around on the car and found that pin 30 at the ECU is purple with yellow. So this seems to be the wire that goes straight to that connector.

The wire at the low oil sensor thingy IS white with pink. It was pretty hard to tell though, it has a healthy coating of oil and other crud. So that's something.

[ZephyrEFI]

Thanks XC for reposting all those diagram's from Dean's thread, that's huge. I know I'd been here before, but since then, I pretty much forgot everything I learned since I wasn't dealing with it directly at the time, I guess.

I was starting to worry I might've fried pin 30 since I ran the car with the Cobra computer last year without having moved the jumper yet. I'm starting to understand now that the manual pin 30 looks for neutral when the car is in RUN, and the auto pin 30 only looks for neutral when the car is starting. BUT... I think I'm okay. I THINK I wired the clutch in switch straight to the red with blue START circuit, not pin 30. So, the white with purple and light blue with yellow circuits are currently not hooked up to anything (and therefore nothing should be fried). I made the assumption I should wire the clutch switch to the red with blue circuit when I saw that the T-5 harness I bought after I did the tranny swap had that circuit jumpered, rather than going to a neutral safety switch. Or so I assumed. But the end result is, the car won't start without the clutch in, I guess. It wasn't the right way to do it, but it works. I'll have to peel back the carpet and look at redoing that correctly.

[xctasy]

Lol, all Good Z---->EFI.

the connector where the O2 harness plugs into the engine harness, does it go over to the connectors near the master cylinder that then goes into the dash harness??????? I know im f-ing my brain over this. lol

Meantime, hook it to the starter wire supply cable.

See this https://www.youtube.com/watch?v=7mTCmpr54U0

See https://www.corral.net/threads/oxyge...esses.2306561/

Very important info.


02 HARNESS:

They made 4 different versions of the 02 harness.

2.3 4cyl versions had 4 wires on the actual 02 cannon plugs so you MUST steer clear of these 02 harness's or you will fry your computer.

V8 02 harness's only had 3 wires going to the actual 02 harness cannon plug that plugs into it.

The 4 different v8 02 harness are as follows:

Speed density only 02 harness (for both manual and AOD),
88-90 5 speed 02 harness,
91-93 5 speed 02 harness
and finally 88-93 AOD only 02 harness.

I add 88 because California was the first year for 02 harness loop and mass air so that was only for those cars sold that year in that state. It was the start of CARB emmisions.. Sometimes i run across them, they are no different than 89-93 mass air 02 harness's

[ZephyrEFI]

So, I got tired of fooling around with year to year changes and just went on ebay and got myself a 1990 EVTM. I found one for $20. I know the last time I looked I couldn't find any, but for whatever reason, now there's a bunch. I suggest you do the same Navy for your year wire harness (can't remember what it is). That way you can be sure of what you need.

I was looking at the O2 harnesses offered on LMR just to see how many there were and stuff. I happened to notice this:

https://lmr.com/item/LRS-8793MTH/Mus...ness-87-93-50L

Seems like a winner to me. It would give me the chance to undo my hackery of those circuits and do it right. I'd like more information before I buy though, like where all those connectors are and what exactly they do. I'm curious if the clutch switches are built in to it or not. Maybe when I get my new EVTM it will tell me. I can see in the picture they don't let you zoom in on what appears to be a light blue with yellow jumper. How relevant.

It would help to know too if the 1993 T-5 still had the neutral switch incorporated with it or not.

[NAVYCAT]

Oh, my harness was already we-done by a pro, and my car passed cal. smog but there is always something going on in my rock hard head that something isn't right lol maybe I should worry about something else.......

[ashley roachclip]

Way too much over thinking going on !

[ZephyrEFI]

Way too much over thinking going on !

I've got a good reason, I swear! Every functional part on my car was transplanted. I started with 2 functioning cars, and distilled them into one, but the Mustang I got my main harness out of (and many other parts that have been subsequently replaced with new) had been thoroughly hacked on. Plus, in a main harness like a SEFI car has, there's only so much you can do to remember where everything goes. Making some huge diagram of where all your plugs go, ain't nobody got time fo' dat! 14 years later, I've still got plugs hanging I still don't know what they do! My engine has never run that well up until this point. Some of those unplugged plugs are probably a big reason for that. Whether the computer knows if the car is in neutral or not is an important bit of information. If it was more sophisticated, it would be throwing codes, but it's not.

I'm just trying to check all the boxes here. Leave no stone unturned. When I first put the car together, I had no idea if it would start or not. Luckily I plugged enough things in that it did. Then when I swapped the manual in, I wandered even farther from the known path. Some of what I did to make the car run was whatever I had to do, like my clutch pedal switch job. It feels good to go back and do things right.

Here's another bit of info I found, the location of that transmission harness and some of the connectors I need to use.



I had removed the Neutral Whatever Switch on the trans (The one on the clutch pedal bracket is actually the Neutral Sensing Switch) because I thought it looked messy with its pigtail hanging there, and the new T-5 harness I'd gotten didn't have a plug for it, so I thought it wasn't needed. Now I'm going to go back and reinstall it so I can do whatever I can to set my engine up to run well.

Some people might be okay with their car having a bunch of components missing or unplugged and an engine that runs "good enough", but I'm not. I want mine done right. Except the AIR system. F*** that mess.

[OX1]

The Upstream 02 sensors never changed from 86 to 95.

You mean the wiring, as the sensor changed connector...

And to muddy the water further, I'll dredge this thread back up
http://vb.foureyedpride.com/showthre...sion-questions

[OX1]

I had removed the Neutral Whatever Switch on the trans (The one on the clutch pedal bracket is actually the Neutral Sensing Switch) because I thought it looked messy with its pigtail hanging there, and the new T-5 harness I'd gotten didn't have a plug for it, so I thought it wasn't needed. Now I'm going to go back and reinstall it so I can do whatever I can to set my engine up to run well.

Some people might be okay with their car having a bunch of components missing or unplugged and an engine that runs "good enough", but I'm not. I want mine done right. Except the AIR system. F*** that mess.

I'm not even sure my orig 86 trans had one, but my 89 trans did so I hooked it up also.
I also found this connector near the radio was disconnected, but there in 86.



Not sure if I disconnected many moons ago putting in stereo stuff, but it runs to that nuetral sensing switch.



and down the the trans





Will also add this on why Ford Looped this stuff through the O2 harnesses.

The O2 sensor harness is cheap and easy to swap out, depending upon how ford built the car.
So ford kept the same body harness and used the O2 harness for different tran's on how
the 30 and 46 got connected.

[ZephyrEFI]

Nice! Great info!

So, the picture becomes clearer. I think it's pretty clear the O2 wiring DID change around the time of the change to MAF. The O2 8 pin connector below the intake tube didn't appear until then. That is a change, no? Ox, let's look at your pics one by one.

1st pic: So, I'm assuming this is a plug that is unplugged in an auto, but plugged in on a manual? And from there, it goes to the clutch switch, correct?

2nd pic: Nice to see I wasn't wrong about the red with blue circuit. That IS what is shown in my pre-MAF EVTM. It does not address the blue with yellow circuit at all though.

3rd pic: This is the connector near the master cylinder, right?

4th pic: Okay, I'm fairly sure I currently do not have 2 plugs coming through that grommet. Probably because I cut one of them off. Hopefully the LMR harness remedies that.

in your post in the other link, it shows that the wire at pin 30 at the EEC is blue with yellow. That jives with what we know about the wiring change around '89. Mine is purple with yellow, leading to the O2 harness, and yours being light blue with yellow never goes there.

Thanks for the explanation about why they did the O2 sensor thing. Makes sense. I wonder if you could say once I get that LMR transmission harness plus having made the change at the O2 harness that I pretty much now have a manual harness.

[erratic50]

Damn ..... with everything going on with your wiring I can only guess you did things the way you did because of the parts car you had.

I'm thinking there had to have been an easier starting point otherwise.


I hope it all works out well and it starts running like you'd expect it to.

[xctasy]

You mean the wiring, as the sensor changed connector...

And to muddy the water further, I'll dredge this thread back up
http://vb.foureyedpride.com/showthre...sion-questions

Your right OX1, I was wrong. Wow, what a bunch of sequenced changes from 1986 to 1995.

Thanks for all the pictures.

[ZephyrEFI]

Damn ..... with everything going on with your wiring I can only guess you did things the way you did because of the parts car you had.

I'm thinking there had to have been an easier starting point otherwise.


I hope it all works out well and it starts running like you'd expect it to.

The only information I had to go on was an earlier year (and therefore wrong) EVTM and the trans harness I got from from LMR. I had no way to know about the wiring changes, and all the shenanigans with pin 30 involved in a manual swap. And who knew there would be vital information hidden under "MAF swap" and "O2 connector" on the forums! What's that got to do with anything?

Of course, an automatic parts car wasn't ideal either, but the price was right.

[NAVYCAT]

damn! im looking at picture 1 and im thinking that I never plugged that in....(I think) my car wont start till I press in the clutch so maybe I did?????? But I was reading that old post and he said his car surged a little till he plugged in the single wire. I think the single wire comes up the left side kick panel I need to look now my brain is really smoking..... But here is another thing, when I connect up my OBD1 scan tool it will not do the KOER test unless I hold in the clutch during the whole testing.......so if what im reading either ground wire 30 at the ECU or make sure that single blue/yellow wire is connected but if it is then ground wire 30? and how? and FYI have a 88 main harness going to the ECU and a 86 dash harness that had the connectors by the M/C changed by pro