Explorer OBD2 Harness Re-work

[Joker11]

I want to keep the emissions system for the most part, minus the fuel tank issue due to it’s complication and incompatibility.

I have the complete VATS system, why not use it?

I get deleting what you don’t want, but why not just clip the unused connectors off as opposed to reworking the harness?

I don’t get why pins need to be moved.

Looking for the logic for re-pinning.

Not arguing, just trying to understand what is happening and why.

 

[DirtDonk]

Glad you're going to run it as is. I like the idea of leaving all the smog stuff I can intact too.
I think it's the physical size of the harness for the most part with most people?
With all the stuff unused, it's just nicer, cleaner and easier to route it around an already compact engine compartment with that many fewer wires to deal with.

I don't know that for a fact, but that's my take on it.

Paul

 

[TTownEP]

I get deleting what you don’t want, but why not just clip the unused connectors off as opposed to reworking the harness?

Some of it is for people not running the 4R70W trans. You move the O2 sensor back up into the engine harness and eliminate the rest that was going to the trans.

 

[904Bronco]

Glad you're going to run it as is. I like the idea of leaving all the smog stuff I can intact too.
I think it's the physical size of the harness for the most part with most people?
With all the stuff unused, it's just nicer, cleaner and easier to route it around an already compact engine compartment with that many fewer wires to deal with.

I don't know that for a fact, but that's my take on it.

Paul

I guess that I will say that you can do anything you want, it is your project...

Not trying to be a dick here... But cutting off connectors that you are not going to use seems... half ass
I am sure it has been done, and will be done. The problem that I see is sometimes circuits share stuff and are interconnected inside the harness. At minimum, the ends would need to be terminated with shrink tubing to prevents shorts or feedback. Troubleshooting issues can be a nightmare. If you are going to make the effort to do a direct transfer, make a clean job of it. Just one persons opinion. And I have done 3 Explorer conversions.
Doug

 

[Joker11]

Ya,
I didn’t mean to leave wires hanging. I just meant it seems like a hassle to unwrap and re wrap just to pull wires out as opposed to capping them off.

I am running a ZF5 spd so I won’t be using the trans harness.

I think it is kinda neat to run a “Mostly” OBD2 system.
Makes repair fun with codes!

 

[904Bronco]

There was a thread here, quite a few years ago, on someone who was testing Explorer stuff to keep most of the things you were talking about.
I want to say Dave, who lived in CO, but has relocated to the South. Not sure..
I don't think it was finished, I just did a quick search look but was UTL. Maybe what he posted will help with your plans...

 

[EFI Guy]

You can leave the engine and transmission harnesses untouched if you like. You may end up with unused plugs but thats not a big deal unless you are like me and ugly wiring makes you twitch. The fact that you can still run it as-is is part of why I offer a firewall harness only rework as an option.

Depinning is easy once you've done a couple of wires you get the hang of it. IMO it's much cleaner than cutting and sealing wires that you don't need. Plus if you depin a wire by accident and find out that you need it, just push it back in. But, if you cut a wire and find out you need it then you need to start splicing.

If you left the firewall harness untouched there would be about 100 extra wires to sift through to find the 10 or so that you need to make it run.

 

[Cooter_76]

Not sure if this is the right place to post this, but I'm hoping to get some tips from others who have successfully completed their Explorer swap. This is an abbreviated version of one of the posts in my Explorer swap thread.

Regarding the firewall harness, I could use some real specific (dumbed-down) guidance.

OBD II port - needs to be grounded (simple enough)

Ignition wires
- Hot in start only
- Hot in start AND run
I know I need to tie these in at the ignition switch, but I'm not sure which terminal each needs to be connected to, and how (specifically) the wires get attached. I can use a test light to figure out the "which", but it's the "how" that has me stumped. Here's a pic of the back of my switch for reference:

Overdrive wires
- Light - needs hot in run on other side of light
- Momentary switch - needs hot in run on other side of switch

Check engine light - needs hot in run on other side of light

Inertia switch
- Run wire in firewall harness to switch
- Need to run a new wire from the switch to the fuel pump

Reverse light - Needs hot in run, plus a 10 amp fuse.

Gauges
- Tachometer signal wire - run to tach gauge
- Coolant temp wire - run to temp gauge
- Oil pressure wire - run to pressure gauge
- Volt meter gauge - Since I had Classy Gauges add this when they refurbished the cluster, I need to run a 12V "hot in run" wire to one side of the gauge, and ground the other side. I've read that people recommend tapping-into the 12V side of the cluster's voltage regulator, and have seen pics of regulators with two spade connectors on the 12V side. Mine only has one connector on this side.

Including the volt meter, I have 5 separate wires that need "hot in run." How and where should I connect these?

 

[904Bronco]

So Pictures...

Back of Ign switch - (75 harness) large black wire in center is accessory post, Not 100% certain on this part... Yellow - is battery feed. Red with black stripe - starter, and ?. brown/green with red stripe - ign, alt reg, etc.

Battery aux terminal - splice into correct wire, run to terminal, run wires from various Explore needs to terminal.

Splice - with a uncovered, seamless butt connector, soldered, covered with lined marine grade shrink tubing.

 

[Cooter_76]

So Pictures...

Back of Ign switch - (75 harness) large black wire in center is accessory post, Not 100% certain on this part... Yellow - is battery feed. Red with black stripe - starter, and ?. brown/green with red stripe - ign, alt reg, etc.

Battery aux terminal - splice into correct wire, run to terminal, run wires from various Explore needs to terminal.

Splice - with a uncovered, seamless butt connector, soldered, covered with lined marine grade shrink tubing.

Thank you! The splicing was the part I couldn't wrap my mind around. I've been watching YouTube videos on the subject, but some of them seemed hokey.

 

[rsensiba]

I have a low mile 2000 mountaineer and I am attempting to run all the electronics possible with the 4r70w. I am using a bare tub I have from my bronco I rolled back in high school then stole all the parts and I am even considering cutting out and swapping the firewall and dash to get the AC, cruise control and tilt column.

If I use the fox body VSS on the Dana 20 output and switch the wiring from the 8.8 axle VSS will the signal be compatible and run the speedo and cruise ect...

 

[Viperwolf1]

Explorers used a VSS to feed the speedo (possibly also for cruise control) until 1998. In 1998 they started using the output shaft sensor in the 4R70W for the speedo. So you should already have that. A problem will be when the transfer case is in low range. The OSS doesn't know what low range is so your speedo will read like you are in high range.

A VSS could be used in the transfer case to correct this if the frequency of it and the OSS were the same or if the explorer computer can accept reprogramming of this parameter. It would take some experimentation and probably a little rewiring.

 

[rsensiba]

Thanks. I unplugged the VSS in the rear diff and drove around the block and everything was working fine. You just saved me a lot of time and probably money! the build plans go on.

 

[markdtn]

I have been searching for a long time on this! Great to find out it can be done. I currently have a 5.0 88 Cougar conversion in a '66 Mustang. I have wanted to do one of these to get to the next level. So If I understand correctly if I have a complete 2wd V8 96-01 Explorer, I can have the ECM flashed to remove PATS, downstream O2s, and fuel tank stuff. I can use the Explorer engine harness and just use the input/output wires on the big connector for ignition, starter, ECM power, oil/coolant sensors (swap for appropriate early Mustang ones), and fuel pump. If I have a 96-98 with 2 fuel lines (return line) then I can use the Walbro in tank pump I already have. If I have a 99-01 with no return then I have to add a regulator at/in the tank. And there is a way to use an "early" canister purge solenoid. Do I have it right? Thank you for this!

 

[Okie69]

Got in touch with Garry and got on the list! Does anyone have a picture or pictures of all of the harnesses and associated items that I need to strip from the Explorer? I'm sure I can figure it out from the videos and multitudes of posts about the subject. Just hoping someone has something like a guide.

 

[Cooter_76]

Got in touch with Garry and got on the list! Does anyone have a picture or pictures of all of the harnesses and associated items that I need to strip from the Explorer? I'm sure I can figure it out from the videos and multitudes of posts about the subject. Just hoping someone has something like a guide.

Garry has a few photos and descriptions on this thread or the other one he started around the same time. His pics show what to keep and where to cut a big chunk out of the main harness that you won’t need. I’m too lazy to go find them myself.


Sent from my iPhone using Tapatalk

 

[Okie69]

Garry has a few photos and descriptions on this thread or the other one he started around the same time. His pics show what to keep and where to cut a big chunk out of the main harness that you won’t need. I’m too lazy to go find them myself.


Sent from my iPhone using Tapatalk

Oh I must not have found that one yet. I don’t think it’s in this one but I very possibly could’ve missed it.

 

[akforsyth]

Curious if anyone has ever managed to source those damn connectors that Gary talks about in his videos? The ones used for the relays.

 

[904Bronco]

Curious if anyone has ever managed to source those damn connectors that Gary talks about in his videos? The ones used for the relays.

If you are referring to the connectors for the factory relay box. No. (See pic)

About two SEMA's ago I went on a mission chatting with a number of electrical suppliers and a few companies that refurbish harnesses asking if they had a source and came up empty handed

 

[akforsyth]

If you are referring to the connectors for the factory relay box. No. (See pic)

About two SEMA's ago I went on a mission chatting with a number of electrical suppliers and a few companies that refurbish harnesses asking if they had a source and came up empty handed

Yeah I thought so... I'll hopefully just rob from another source...