Bronco II 4.0 swap wiring problems. Help me

[Jnwright]

Hi all,
I’m helping a friend of mine finish the engine swap he started years ago. Originally the guy who did the mechanical work cut the plugs out and basically took the money and ran. I’m here to help and it’s a mess. Everything explorer is out of a 1991. I’ve followed the tech guide that James Oaks authored and am running into a few problems. I have it turning over but not firing.
1. Pk/blk from Ex harness I can’t find the mate. Can I run it under the passenger side dash to the pk/blk wire from inertia switch?
2. Alternator idk where to start cause he keeps it real cryptic in his original post. “Contact me for wire colors” anyways I’m just gonna try the diagrams see if I can figure it out or it’d be stellar if someone that knows could tell me.
3. Blk/lb wire from big white plug says to find over on passenger side. Idk I’ll try to find it but again any help would be appreciated.
Pic is of how I’m trying to make it work and look decent still in progress but got a plug out of a f-150 that has 14 connector so almost all wires are going through it now.
Please help any suggestions or advice is welcome.

 

[jtaborsky]

What year is the Bronco II?

Black/pink iirc is for reverse lights. It has been a long time since I did the swap.

I had problem with alternator exciter wire right away. Turned out i removed a fuse i needed. Did you use explorer fuse box?

Why is your picture called rats eat?

 

[Jnwright]

It’s an 89 bronco.

I’m not sure what fuse box was used. I believe it’s the explorers.

Auto correct lol I was trying for rats nest…

Looking at the inertia switch under the dash the two wires leading into it are dg/y and pk/blk.
One of the only wires I have left on the EX harness is pk/blk. Also Jim’s wiring tech sheet for this swap labels both vehicles as pk/blk = fuel pump. I want to know if I can run it through the engine bay and splice it by the inertia switch to make the fuel pump pump. Or is there a better option?

Also forgot to mention mines an automatic.

And the red wires were mixed up. Do I need to trace them so as I can get them to the correct place? Or is red just a common wire that runs multiple functions and it doesn’t matter?

 

[Curious Hound]

Pk/blk should go from inertia switch to fuel pump.

You want your alternator/charging system wired like this.

https://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_charging_1991_1.JPG

 

[Curious Hound]

Black/pink iirc is for reverse lights. It has been a long time since I did the swap.

That is correct. But he is dealing with pk/blk.

Primary color is listed first. Stripe (marker) color listed second.

 

[Curious Hound]

The blk/lb wire goes from the coolant temperature sensor to the temperature gauge in the dash. Not sure which end of that you can't find.

Engine will run without it be ause the engune uses a different 2-wire sender for temperature. The blk/lb only serves the instrument cluster.

 

[Jnwright]

Pk/blk should go from inertia switch to fuel pump.

You want your alternator/charging system wired like this.

https://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_charging_1991_1.JPG

Thanks CH.

I have a few things need to be “ironed” out.

The pk/bk highlighted in the pic comes from the EX ecu doesn’t go anywhere because the B2 already has it. Or do I need to splice it in somewhere along the line? Originally it was in a 4 pin plug along with the VSS, whatever that is.

The alternator diagram helps thank you. Can you tell me what are the four wire colors I need to splice 2 from EX and 2 from B2.

I think I can figure out the bk/lb thanks for that info as well.

Also please lmk about the plain red wires do I need to be precise about where they connect? I just picked them at random.

 

[gaz]

@Jnwright
If it cranks but does not start, you need to know if it is getting fuel or spark. The 50/50 test will resolve this:
• get some starter fluid (this goes smoother with an assistant but can be done alone)
• remove the air inlet duct from the airbox to the throttle body
• spray a modest amount of fluid into through the throttle body to the intake manifold (try this 4 or 5 times to determine whether or not you are getting an ignition spark.
1) If it starts you have an ignition spark but no fuel
2) if it doesn't start, you do not have ignition spark...hence the 50/50 name

After performing this test, you can go back to sorting out your harness issues, unless of course the harness is at the root

 

[broncc]

I have a thread from when I did mine

Thread 'Wiring diagrams, torque specs, RABS help'

Mar 6, 2021

Sorry for such a data heavy thread but I'm not sure where to put these exactly. I'm sure they will be useful, though!

• broncc
• Replies: 0
• Forum: Submit A Technical Article (Not a Help Forum)

• 

"b2 wires" and "4.0 obd1" are what you're looking for. The wiring colors change a lot so it might help to just peek in the harness every time it splits and trace them to their destination.

Chucked some starting/charging diagrams for the two