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4.0 swap Simplify harness


410Fortune

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You can do it!
I bought my BII for $500 from my dad, it had a terrible miss and had sat in the barn for a year
I drove it daily for more then 20 years then I built a 4 door explorer to help with daily duties and towing.
My BII sat (barely driven) for like 3 years because multiple issues stacking up and Colorado?Denver will not emissions with 35" tires. So we moved to ID 2 years ago and I started to get her back on the road. Now I am daily driving her again and it feels so good! The 4x4 is just plain awesome...had to use yesterday to take kids to school in blizzard conditions, YEAH!!

I have the same dash/body harness she has always had, all 1988 in there. I have modified it quite a bit, first it was 2.9, then 4.0 with stick, then 4.0 with auto, then finally 5.0 with auto....same wires on truck side.

You can do it!! Once you have it all mapped out on paper, then you start cutting things on the truck side so you KNOW where each wire is going and WHY
 

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Joined
May 10, 2018
Messages
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Location
The U.P.
City, State
Sault Ste Marie, MI
Year, Model & Trim Level
85' B2 XLT
I have all the wiring books from 89-94 and then some other various books and schematics as well
I will share with you some 4.0 wiring info that will be very helpful, I might have to get the papers and scan them in
I have piles of notes from each conversion I have done over the years.....

The power dist box gets many wires removed, as does the big white plug, and just a few from the engine harness
Most of the wires you take out will be from the dash, power, under hood ABS type stuff.
I routed ALL the wires on my BII along the back of the engine, nothing through the intake or around the front core support...much cleaner this way
I'm in the process of doing a 4.0 swap with an 85' Bronco II and a 92' Explorer. I have the 4.0 in and mounted to the B2 manual transmission, just started to put wiring harness from Explorer in and the big white plug appears terrifying-any help would be greatly appreciated.
 


Joined
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Messages
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Location
The U.P.
City, State
Sault Ste Marie, MI
Year, Model & Trim Level
85' B2 XLT
I have all the wiring books from 89-94 and then some other various books and schematics as well
I will share with you some 4.0 wiring info that will be very helpful, I might have to get the papers and scan them in
I have piles of notes from each conversion I have done over the years.....

The power dist box gets many wires removed, as does the big white plug, and just a few from the engine harness
Most of the wires you take out will be from the dash, power, under hood ABS type stuff.
I routed ALL the wires on my BII along the back of the engine, nothing through the intake or around the front core support...much cleaner this way
I'm in the process of doing a 4.0 swap with an 85' Bronco II and a 92' Explorer. I have the 4.0 in and mounted to the B2 manual transmission, just started to put wiring harness from Explorer in and the big white plug appears terrifying-any help would be greatly appreciated.
 


410Fortune

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well you should actually be removing the big white plug, identify the wires in it and find their mates in the 1985 body harness
There are only like 16-20 wires in a 1985 truck that talk to the dash
You will need to convert the 85 to fuel injection, some sort of BII fuel system I would use a 89-90 BII system they have a single in tank pump just like a 92 explorer
I have wiring info for the 92 explorer big white plug, you should start a thread of your own so we can see what you have going on and help you!
 


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Location
The U.P.
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Sault Ste Marie, MI
Year, Model & Trim Level
85' B2 XLT
well you should actually be removing the big white plug, identify the wires in it and find their mates in the 1985 body harness
There are only like 16-20 wires in a 1985 truck that talk to the dash
You will need to convert the 85 to fuel injection, some sort of BII fuel system I would use a 89-90 BII system they have a single in tank pump just like a 92 explorer
I have wiring info for the 92 explorer big white plug, you should start a thread of your own so we can see what you have going on and help you!
ok thanks, I have the fuel system worked out using 86-88 B2 new parts & fuel lines from the Explorer donor
 


410Fortune

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allright the 86-88 Bronco II uses a boost pump in the tank and a high pressure pump on the frame rail, this system is a real PITA
I also have a 1988 Bronco II
What I did was remove the high pressure pump from the frame rail and simply added a second fuel filter in its place
Then I installed a 89-90 Bronco II sending unit in the fuel tank along with a 89-90 BII pump in the tank
This is a much better setup then the dual boost pump, high pressure pump setup...........
I took it a step further when I went v8 back in 2005
I now have a 93 explorer sending unit grafted to a 88 BII drop in tank setup, using a walbro 255lph pump....I used the 93 explorer sending unit because nobody makes an aftermarket fuel gauge that will work with the voltage signal from the 88-85 BII and I do not have factory gauges.
I also cut an access panel in my cargo area so I can easily replace the fuel pump, this way I don't get stranded on a trail....
BII's kick ass :)
 
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85' B2 XLT
Looking for similar assistance in regards to wiring everything up. 85' B2/92' Explorer, really overwhelming
 


410Fortune

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You need the 1985 Bronco II wiring book
You need the 92 Explorer wiring book
Then identify the wires on the truck side (there will be a few plugs coming out of the firewall below the brake booster) these are the wires that talk to the ignition, dash, and fuel system
Make a map of each wire color, circuit number, and destination

Now do the same thing for the 92 Explorer big white plug and you will see all of the wires on the 85 side of things will have a match on the 92 side of things

use the 85 style plugs and attach the pins to the 92 wires so you create a 92 harness that plugs into a 85 truck.
You will need to convert the 85 to fuel injection
You will also want to remove all of the 85 under hood wiring, alternator charging circuits and power wires.....leave the headlights and light wiring in place.
You should plan to add the 4.0L power wiring to the 85 under hood as the 4.0 is expecting to see a EEC relay, fuel pump relay, power feeds for the internal fuse box, and more

.
 


Joined
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Location
The U.P.
City, State
Sault Ste Marie, MI
Year, Model & Trim Level
85' B2 XLT
You need the 1985 Bronco II wiring book
You need the 92 Explorer wiring book
Then identify the wires on the truck side (there will be a few plugs coming out of the firewall below the brake booster) these are the wires that talk to the ignition, dash, and fuel system
Make a map of each wire color, circuit number, and destination

Now do the same thing for the 92 Explorer big white plug and you will see all of the wires on the 85 side of things will have a match on the 92 side of things

use the 85 style plugs and attach the pins to the 92 wires so you create a 92 harness that plugs into a 85 truck.
You will need to convert the 85 to fuel injection
You will also want to remove all of the 85 under hood wiring, alternator charging circuits and power wires.....leave the headlights and light wiring in place.
You should plan to add the 4.0L power wiring to the 85 under hood as the 4.0 is expecting to see a EEC relay, fuel pump relay, power feeds for the internal fuse box, and more

.
Much appreciated-I'm that far, just need to figure out the wiring, so to the books I go.
 


410Fortune

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So once you have the books the notes I posted on page 1 will be really helpful
The BWP (big white plug) for the 92 is listed in detail with each wire color and circuit number and destination.
If you need any more details from those notes as you get deeper in just let me know
First things first, I clean the harness, cut all the factory wrapping off and then get ready to start labeling wires that stay and removing wires that don't
 


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Location
The U.P.
City, State
Sault Ste Marie, MI
Year, Model & Trim Level
85' B2 XLT
So once you have the books the notes I posted on page 1 will be really helpful
The BWP (big white plug) for the 92 is listed in detail with each wire color and circuit number and destination.
If you need any more details from those notes as you get deeper in just let me know
First things first, I clean the harness, cut all the factory wrapping off and then get ready to start labeling wires that stay and removing wires that don't
ok, much appreciated. I pulled the harness from the explorer last night for the fuel pump and there's obviously a couple of leads that wont be needed (ABS/limited slip) that I noticed right away. I'm waiting for the pump (88-90 b2) to see what end it'll need so I can change if needed. I glanced at the diagrams for a few minutes, never had to do this, so a bit overwhelming at this point.
 


410Fortune

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one wire at a time
start with pin 1 on the BWP locate it in the 92 book and follow where it goes, write it all down
In 20 years your notes will look like mine!!
 


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Location
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Sault Ste Marie, MI
Year, Model & Trim Level
85' B2 XLT
one wire at a time
start with pin 1 on the BWP locate it in the 92 book and follow where it goes, write it all down
In 20 years your notes will look like mine!!
Not seeing what I need in the book I have other then the general diagrams, not the plug itself. Also need the info for the 85' B2 wires in the firewall that I need to join up to. So frustrating.....
 


ghosttrain2

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Winnemucca,NV
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Winnemucca,NV
Year, Model & Trim Level
1986 Bronco 2 XLT
finished a 4.0 swap in my '86 Bronco 2, used a '94 donor, and converted from an A4ld in the Bronco, to a 5 speed. I also have the wiring books for both, the '86 one was about useless. Too many wire colors that didn't match the book. Having been a dealer mechanic when these were new, made this easier. I used the underhood fuse box, pulled out the unneeded fuses and relays'.I have been driving it, and it is a whole new truck with the 4.0.
 


410Fortune

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yeah it makes you wish the BII never came with a 2.3, 2.8 or 2.9...if they were all 4.0 then they would never have been given such a bad wrap!
Well done!!
 


ghosttrain2

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A/C is charged and working, Cruise control adjusted and working, all the '86 gauges and tachometer working just fine with the 4.0. Love it!
 


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