Explorer OBD2 Harness Re-work

[EFI Guy]

Gonna bump this thread. I am swapping a 1999 Ex 5.0 into my 1985 Bronco II, and have run across your videos and it looks like something i think i can tackle. Doing research, what are people doing for the fuel systems?

For the 99-01 systems, I recommend either adapting the entire fuel pump/regulator assembly to your tank. Or, adding just the regulator to one of the aftermarket EFI tank offerings. In tank pumps suck to replace, but they have a much higher life expectancy IMHO.

If you are dead set against an In tank pump... I would use a low-pressure pump to feed a high-pressure pump mounted on the frame rail. Then use an aftermarket regulator like this one. Set the pressure at 65 PSI, run the return back to the tank, and do NOT connect a vacuum line to it.

 

[Tom Dummer]

You're so far ahead of us mere mortals that it makes my head hurt!

 

[JoshT]

Couple questions

Air conditioning:

Note, the way I'll show you to wire in A/C will remove the PCM control over the A/C relay so A/C will NOT be disabled during wide open throttle. You will still get the bump in idle speed when the compressor cycles. Also, if you are not running A/C you can use the A/C input for a high idle switch which can be handy for winching, on board air, etc...

41-Dark Green/Orange or Purple*** This is the power input to signal that A/C is on. Needs to be hot whenever the compressor is engaged. (This will go to your toggle switch for high idle if desired)
69-Pink/Yellow -This is the wire the PCM uses to control the A/C relay (removed using my method mentioned above)
86- Black/Yellow- using my method this wires goes to ground if using A/C or high Idle.

*** On later harnesses where pin 41 is purple, I like to put pin 67 Purple/white in its place. There is another purple wire that we will use so doing so can eliminate the duplicate color and avoid confusion***

---------------------------------------

VSS:
VSS is not required if using a 4R70W. It is only required if NOT using a 4R70W AND you ARE keeping EGR or EVAP.

33- Pink /Orange - VSS-
58- Grey/Black- VSS +

AC:
If I wanted to keep PCM control over the AC compressor I would just leave these three wires alone right? This is going into a street truck/cruiser instead of a Bronco so I'd kinda like to keep the WOT cutout. Could this be switched so I could switch the WOT cutout from computer controlled to disabled if so desired?

VSS:
I plan to use a tablet and digital dash setup for my gauges starting out. If I wanted to be able to read vehicle speed from the OBDII port, would I need to keep this VSS or does the PCM pull speed from elsewhere? FWIW I am keeping 4R70W and deleting EVAP and EGR.

 

[EFI Guy]

If the Ranger you are working with is a similar year, it might be as simple as just leaving the wires alone in the engine harness, or possibly swapping some pins in the C115.

If you are building a standalone harness and you want the PCM in control of the compressor you need to add a relay for it. You also need to wire in the high and low-pressure switches. On the 96-97 you could interrupt the signal on the pink-yellow to override WOT control. Don't do that on the later ones, you would lose the high-pressure safety shut off. On some computers I can change the relay type from NO to NC in the tune, but honestly, if I did the extra wiring needed for PCM control I'd just leave it alone and let it work as designed. I got lazy and just cleaned up the factory diagrams a bit:

VSS get's tricky, especially for the Ranger crowd. I typically make some changes in the tune that removes VSS and makes the PCM use the OSS signal instead. My reason for doing that is the Explorer PCM does not have an input for low range, and 98 and later harnesses don't have VSS wiring running down to the trans. If the OSS and VSS calculate too far off it can throw you into a limp mode. There are some tricks I can do to prevent that in the tune, but I think it's better to just remove VSS unless you need it for other reasons.

With VSS removed you will not get a Ford VSS pid using Torque or other software. However, you still get vehicle speed under generic pids using the calculated value from OSS, so a tablet based speedo will work, but it's only as accurate as the final gear and tire calculation. Typically never more than 2mph off when compared to GPS. The tablet I'm using has GPS in it, which would be my preferred method if you're using a tablet for gauges

Now if you're 2WD only, and have the wiring and provision for a VSS down at the trans then I would absolutely keep the VSS as long as your gearing and tire size is close to the original Explorer or you properly tune for it.

On the later stuff where there is no VSS provision, you may be able to use the Explorer ABS controller in the Ranger to generate VSS based on the rear diff. However, it's not something I have ever done, and there could be other ill effects in doing that that may compromise safety. So, I'm not condoning it, just saying it may be possible.

 

[JoshT]

It's an 86 Ranger, but there isn't a bit of wiring in it. I'm kinda ashamed to admit it, but I had big aspirations when I started and that was the first thing to go. I had planned to swap in the whole explorer chassis harness, but that ain't gonna happen now. Right now I am just trying to make the engine run kinda like Wyflyer in post 55 of this thread. After that I'll figure out what I'm going to do for the rest of the wiring.

Currently the truck doesn't have AC, but it's something that I will be adding. Want to make sure that I have the right wiring in the harness for when that day comes.

It's a 98 Explorer donor FWIW. While I also have and will be using the axle from said Explorer the tire size will be a fair bit off. Explorer was a 255/70R16 while this truck will wear a mustang's 245/45R17. So I'll be running tires about 5" shorter in diameter.

It is a 2wd, but VSS sounds like it would be more trouble than it's worth. 86 Rangers didn't have ABS or provisions in the brakes for ABS, while I could probably adapt it with the suspension and brake components I'm using, I agree with you on the possible side affects. Initially I was going to attempt it, think I had figured out what would be needed to basically bolt it in, but then realized it wouldn't be programmed/valved right for the much lighter Ranger's weight distribution.

It's funny, I was already planning to go with a GPS speedo when I eventually get gauges. Like that it's independent of gearing and tire sizes since I'm really not finalized on either one yet. Not sure why I didn't consider Tablet's GPS for speedometer purposes. It'd definitely be the more practical way to go for now.

Heck at the moment I'm not even sure the Ranger is getting built. This early Ranger's suspension will handle the V8 fine for straight lines, but I want to twist and turn which seems like a car suspension would be better suited to. I also looking to get into a full size truck and really like the bumpside F-series, so this engine might get redirected to that for the short term (long term would be the 390 and 4wd '68 F-100 frame I have). So right now I'm just focusing on getting the engine running, I'll figure out the rest later.

 

[JoshT]

Just about got the engine harness wiring figured thanks to your guidance. Just a mockup right now got spade terminals connected directly to relays and no holders at the moment to test things. Will be going a slightly different direction on the fuse and relay box. I wanted to have all my engine related relays and fuses in the same box so I ordered one of these off amazon:


^click for link

Holds
6 mini fuses
5 Bosch style relays
1 Toyota relay (I'm not using but available through same link)

Not sure how it would fit in a Bronco, but I think it would be easy enough to make it work. Since I'm planning to keep A/C and Alternator wiring in the harness, it'll give me all the fuse and relay spots I'll need in one tidy box. I won't be using the Toyota relay slot, but it's there if I need it someday. Just throwing it out there in case anyone else is interested.

The diagram below shows how you should change the wiring at the solenoid to work with the Explorer starter. I recommend keeping a fender mounted solenoid especially with a later harness that has very small start circuit wiring. If you are not using the 4r70w then you can use your existing Bronco wiring to feed the S terminal on the solenoid. If you are using the 4r70w then the wire that you will use to feed the S terminal on the starter solenoid will either be red/blue, or tan/red depending on year.

I'm using the Explorer's 4R70W and stock mini starter. I can just do away with the fender mounted solenoid (don't currently have) and run the battery cable and the start signal wire from the engine harness straight to the solenoid on the mini starter right? The solenoid acts like a relay right? So it shouldn't need much amperage from the start signal wire to engage the starter. I can add a starter relay/fender mounted solenoid if it's needed, but I'm not really understanding the need.

 

[EFI Guy]

I've used that same box before on a few builds, that's cheap! I'm happy with it, but I don't like the fuses aren't bussed.

Do not use the factory start signal wiring to go directly to the starter mounted solenoid! The draw is too much, especially on the 98 and later harnesses. Either use the fender mounted solenoid or use a relay and larger wiring. I'd say 14 gauge at a minimum, I'd be tempted to use 10-12.

 

[Wyflyer]

Just about got the engine harness wiring figured thanks to your guidance. Just a mockup right now got spade terminals connected directly to relays and no holders at the moment to test things. Will be going a slightly different direction on the fuse and relay box. I wanted to have all my engine related relays and fuses in the same box so I ordered one of these off amazon:

^click for link

Holds
6 mini fuses
5 Bosch style relays
1 Toyota relay (I'm not using but available through same link)

Not sure how it would fit in a Bronco, but I think it would be easy enough to make it work. Since I'm planning to keep A/C and Alternator wiring in the harness, it'll give me all the fuse and relay spots I'll need in one tidy box. I won't be using the Toyota relay slot, but it's there if I need it someday. Just throwing it out there in case anyone else is interested.

My harness has one of those same type fuse holders. I love the box, but the mounting ears are not symmetrical. One is lower than the other, and also sticks out farther from the housing. If you're into mounting things straight and flat and level it'll fight you!

 

[JoshT]

Yeah I noticed that, but wasn't too worried about it. Heck I'm not even sure where it'll be mounted yet. Figure it it doesn't mount up nice I'll either make a spacer for the short ear or cut both off and make my own bracket.

 

[DirtDonk]

A spacer for the leg, OR a curved/bent mounting plate with a spacer on the back.
That way, even though you still need the spacer, the box itself is mounted to the flat surface (nice aluminum in my mind) and any spacers, or legs are hidden behind the plate.

No difference in function. Just a little more complete "look" added.
And a bonus would be that if you make the plate right and mount things in the right location, you could even hide some of the wiring behind it.
I'm thinking that the fender skirt/apron is a good example. The plate could be made to bring the box out beyond the fender's bolting lip and some wiring could be run behind it.

Paul

 

[904Bronco]

A small spacer and an L-shape piece of aluminum and you are good.

 

[DirtDonk]

Is that all the offset is then? Heck that's hardly thicker than a regular washer. Not something that would require hiding as a spacer then. Looks good on that Grabber Green!

Paul

 

[Wyflyer]

I mounted mine by building a custom aluminum bracket to level & square it with the top of the fender. I mounted the circuit breakers for the dash power & Vintage Air under the bracket to protect them & clean up the installation.
The alternator fuse is mounted beneath the fuse box too.

 

[Kyle B]

Just watched both of the videos. Thats some great info and i cant wait to tear into my harness. Im gonna need my pcm flashed to delete a few things. Is the @gmail email address still good?

 

[chuzie]

I mounted mine by building a custom aluminum bracket to level & square it with the top of the fender. I mounted the circuit breakers for the dash power & Vintage Air under the bracket to protect them & clean up the installation.
The alternator fuse is mounted beneath the fuse box too.

I see the maxi for alternator, but do you have a mega fuse for starter hidden somewhere too? I really like your bus; super clean.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Crackin1]

I have a question what four wires do you connect to your fuse panel and where do you feed it from. Watched the videos but just can’t seem to pin it down.

 

[Wyflyer]

I see the maxi for alternator, but do you have a mega fuse for starter hidden somewhere too? I really like your bus; super clean.

thanks, No there's no megafuse on the starter wire. As far as I know thats not common.
I used the 5.0 starter with the solenoid on the starter.

 

[EFI Guy]

I have a question what four wires do you connect to your fuse panel and where do you feed it from. Watched the videos but just can’t seem to pin it down.

You feed power to the 4 relays from the fuse panel. If you use a larger fuse panel you can feed the keep alive memory/OBD2 port and the yellow/white alternator wire with their own fuses as well.

 

[Crackin1]

Ok still confused the 14 gauge green wire I added to go to the inertia switch. Where does it go on the relay box?

 

[904Bronco]

Ok still confused the 14 gauge green wire I added to go to the inertia switch. Where does it go on the relay box?

It has been a while since I looked at the video...

Fuel pump gets power from one of the relays... 14G Pink wire with black stripe is Ford's color. That power wire travels through the inertia switch to the fuel pump. The other side of the pump is ground.