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OBD to OBDII conversion

40K views 68 replies 17 participants last post by  Wile E. Coyote Jr. 
#1 ·
Just wondering how hard it would be to convert it from like 96/97 explorer? I found one thread but no info. Is this something that just wouldnt work?
 
#34 ·
If I were doing this swap, I would start with an explorer ECM, and a 4.6 tbird wiring harness, and modify the 4.6 harness to fit the 5.0 and repin as needed at the ECM. That would put all the wiring in the right place for where the components are, and then you know you won't have any issues with signal types not matching because the ECM and all the sensors on the engine would be made to work with one another. Another advantage is the 5.0 explorer had a 4R70W trans, so you could easily run a 4R70W behind a 5.0 in an MN12 doing it that way.
 
#35 ·
I was just wondering because I have a spare 4.6L ECM. I posted the question in the EEC section. I still have to get the harnesses.
The M5R2 will eventually go in this car so I'll probably have to get a tune to shut off the auto transmission functions. Or build a really good circuit to compensate. I think a tune would be better.
Do you know what year the Explorers got the COP ignition?
 
#36 ·
The explorers never got COP. All the 5.0 explorers used a waste spark system. You would have to do some more research, and maybe grab some sensors off a 4.6 and an explorer 5.0 to compare them, to see how many difficulties there would be running the 5.0 on the 4.6 ECM. Both are wast spark systems, with multiport EFI and 8 cylinders, so the main thing that would be an issue is whether the crank and cam sensors output the same signal. If they do, then all the other sensors can be adjusted for in the tune. If they don't, then you would have to find a way to either alter the signal, or adapt another sensor that would use the same signal the ECM is looking for. My thinking is that a project like this you are going to need a tune anyway, so you can shut off any parameters you don't need of the explorer ECM, and the 4.6 tbird harness will plug into the explorer ECM, so you would just need to repin a few things at the connector to match the locations on the explorer ECM, and then lengthen wires and swap connectors as needed to get the 4.6 engine harness to fit the 5.0. Both of those things could be done out of the car, so you could take your time, and have plenty of room to work, and then when you are ready to do the conversion, pretty much everything will be plug and play.
 
#37 ·
Yeah, if the sensors read totally different then I probably would go the Explorer route.
And I agree, assembling stuff on the bench is the best way to go. Rather have everything ready and sorted out before the install.
 
#38 ·
I would believe that the Crank sensors would have the same output signal, since they (4.6L and 5.0L Explorer) seem to share the same basic Variable Reluctance (?) sender

Cam sensors seem to be different, Explorer being a Hall effect style Verses the 4.6L Variable Reluctance style.

Now the question would be, if all was equal, the timing of the signals would they be the same?

So to me doing the say '96/7 MN12 harness with a Explorer ECU seems the better way, also you have a good starting point on the harness.
 
#39 ·
Thanks 91 XR7 and Mike for all of this info.

If I find anything related from my old hard drives I'll post it here. I know I've got articles from people adapting these sensors to old hot rod Windsor engines and even 460 motors. I need a secretary.
 
#41 ·
rwenzing said:
Ford used a Hall Effect CMP from 96~98 and a Variable Reluctance Sensor CMP from 99~01. Each takes a different alignment tool. For identification purposes, HE sensors have 3 electrical pins, VRS have 2.
I found it here: http://www.explorerforum.com/forums/showthread.php?t=207905
The thread deals with synchronizing the Explorer cam position sensor but I found the above excerpt to be interesting.

I'm posting this in both threads.
 
#44 ·
I got the engine from a guy on OfferUp he said it came out of a 97 Thunderbird but it's a 4.6 V8 steeda motor and it had the transmission already with it and it says 4.0 on it the one that came out of the 3.8 said 22 l. I already got it all in there I have the engine harness but I just was wondering how I'm going to hook it up? the connection on the driver's side firewall is round. would be easier to just go get the rest of the wiring through the dash from the junk yard or can I just splice them

it doesn't have to be perfect just run for now
 
#45 ·
Did you get the ECM with it? The engine control harness goes to the passenger side. The wires for the gauges and warning lights goes to the drivers side. The 97 dash was different, so I'm not sure if everything will work, someone else may know that piece better.
 
#46 ·
It will require a lot of rewiring, and that may be an understatement. You really will need a complete donor car/harness. The engine and transmission harness needs to be swapped. To make the transmission harness work, which connects through the dash harness, you will also need to rewire the dash and adapt it for the existing body harness which is substantially different as well. Pick up the EVTM for both model year cars and do some reading so you can decide what approach and level of work you're up for.
 
#49 ·
This is how I ran my 1990 SC when I swapped it to a 96 Explorer 5.0.

I ran the engine, engine harness, and computer completely separate of the body harness.
I ran them on their own fuse boxes with their own relay box which also controlled the fuel pump.
I spliced the gauge wires from the eec into the dash wiring and the fuel pump wires into the control wires from the eec.

That round connecter on the driver side is your body harness. Do not mess with it.

Kinda busy rn so I cant go into too much detail but when Im free I will elaborate more.
 
#52 ·
Ok. Things youll need.
Easy access to wiring diagrams
Aftermarket fusebox and relay box. You can get them at AutoZone for $20 each.
Spare wiring of varying colors and gauges.
Soldering iron, solder, and knowledge of how to solder.
Self tapping screws and washers
Four feet of 4 gauge wire
And a lot of patience.

Here we go. Full thread hijack at this point boys.

41827

This is what I am using as my example. It is a 1990 SC with an explorer 5.0, paired to an m5r2. It was built as a drift missile, so everything done was just to make it run and that was good enough.
41828

Leave your factory starter relay inplace, but add a 4 gauge wire to the run side. Same side the factory body harness is connected to.
41829
41830

Run that wire to your added fusebox. I used the factory 96 explorer box, but a fusebox is a fusebox.
41831

This will house your fuel pump fuse, eec main fuse, o2 heater fuse, eec memory fuse, and ignition coil power fuse. The eec memory fuse will also be used to keep power to the OBD2 port.
41832

The relays control the fuel pump, eec, o2 heater, and ignition coil power. You can also add a relay for your fan, since the Tbirds EEC has a signal wire to kick that on.
41833

Get your self one of these wire brackets(?), off a 96 or 97, to protect the harness as from getting cut or shorting to the body. You can also see where I added my EEC ground on the right.
41834

These are the signal wires coming from the EEC and engine harness for rpm, oil pressure, coolant temp, speed, obd port, ect. I honestly dont remember every wire as I did this swap in the summer of 2019 within a 3 weeks period. Fun fact, I put on 25lbs during this build.
41835

Here is the wiring popping through to the driver side, under the dash and then up to the instrument panel. That was the easiest was I found to cross them over.
41837
And thats that! I will not get into which wire goes where or does what because an explorer harness is different from a birds. But the swap you are planning is similar enough to mine to where this, imo, will probably be helpful.
 
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