1987 Bronco II manual to a 4.0 OHV

[djisthemanstan]

From a harness perspective: What donors should I be looking for?

 

[SenorNoob]

90-92 Ranger
90-94 Explorer or Mazda Navajo

It's by far easiest to get a whole donor vehicle. I didn't and it ended up costing me a lot more. I see you're in TN too. I'm in Lafayette. Facebook marketplace usually has an Explorer with a bad automatic transmission for a decent price.

Edit: Do you want to keep the 87 dash? The wiring can be plug and play if you don't.

 

[djisthemanstan]

Ford 4.0 Liter V-6 Conversion Wiring (From Explorer to Bronco II) - The Ranger Station

Submitted by bronco (forum member) Want one of these?? Then here’s some wiring help……………. Here (above) is where all the wiring took place. Here is how to swap pins. Get a couple picks like the ones shown below. Pick out … Continued

www.therangerstation.com

I found this. I guess Im wondering if an early ranger would be more exact wiring with less splicing. Do you recall any particular complications? splices?

 

[SenorNoob]

I kept my 87 dash. The only splices I made were at the firewall on the driver's side. The engine-computer harness and the lighting are not bad to separate. I still have all original 88 lighting wiring and inside the cab except for the few inches to the computer in the passenger footwell. I did get the entire Explorer underhood harness and remove the thing I didn't need but that's not strictly necessary. After having done it, I would take the inside part of the big white plug (It'll make sense when you see it.) and about a foot of wire. Then cut the factory harness under the hood a foot from the connectors the 87 uses in the same place. (It'll be a few connectors. I don't remember exactly.) Once that is done you those 2 one foot pieces inside to make an adapter from your in-cab connectors to the 4.0 harness.

The only wire I remember being interesting was the Red/Light Blue for the neutral-clutch safety circuit. I remember starting mine a couple times by jumping the starter relay. Oddly enough everything else was just matching wire colors in my case.

 

[djisthemanstan]

sounds like im in it now. honestly i almost turned around from this. what about your transmission? my understanding is having the automatic explorer harness will pose issues for a manual... Do you have any photos to post? I saw a photo of the 'big white thing' you mentioned. LOL

 

[SenorNoob]

I don't have any useful pics of my wiring. At the time I didn't have a smartphone and working mostly outside in January made getting the camera out a little too much work...

There is sub-harness on the 4.0 harness for the transmission. The cleanest way would be find one from a manual truck/suv. It doesn't have to be from a 4.0. Any manual from 90-92 will have it. I couldn't find one so I took the automatic harness and combined it with the factory transmission connectors. The only thing on a manual transmission is the reverse lights and maybe a neutral switch. Not all manuals had a neutral switch. The wires are in the automatic harness too. They just connect differently.

Edit: I just got a few pics.

This is where the Big White Plug would later be.

This is a much wider shot of the same area. All of my splices are here. It's not as complicated as it looks. Most of that bundle is extra power wires for things the Explorer (It was a Limited, lots of options.) had that I didn't need. Think power seats, windows, mirrors, etc.. I actually used a couple of them to power my lights. You can relays mounted there.

This is one of the factory connectors you want leave. If you can unplug it, it can be made into part of the adapter. There are only 2 on my truck. I couldn't get either one unplugged. That's why I had to make my splices outside.

 

[djisthemanstan]

'Just got pics' Wheres the motor! lol "Edit: Do you want to keep the 87 dash? The wiring can be plug and play if you don't." if its easier to pull the dash sure. honestly zero splices sounds ideal. Regarding the Auto wiring harness: "The only wire I remember being interesting was the Red/Light Blue for the neutral-clutch safety circuit.'' it sounds like this is the wire on the bronco II to look for. I dont really see reverse lights being a necessity. forgive my ignorance, but what about the tachometer? is this dictated by a cable going to the trans or is this electronically controlled via wiring?
Now I see why your saying a donor is cheaper than buying the motor:
4.0 Engine, complete with all accessories
Throttle cable and cruise control cable/assembly (if desired)
air tube with air filter housing, and Mass Air Flow Sensor
complete wiring harness from under the hood
ECM Computer
wiring harness from A/C Fan
A/C Lines (If A/C is desired)
A/C Condenser (If A/C is desired)
A/C Compressor (Required)
Transmission (Ideally)
Radiator
Motor Mounts (although while it is out is a good time to buy new ones)
Exhaust Crossover Pipe
Catalytic Converter(S)
Fuel Lines
Sending unit/fuel pump assembly (if current motor is carbureted)
Power Distribution box
Charcoal Canister
Inertia Switch
EDIS Module

 

[SenorNoob]

There is a single wire to hook up for the tach. The signal did come from the TFI. On the 4.0, it comes from the EDIS. That wire is part of the BWP.

Here are a couple pics of my latest engine. I put it in in May last year.

These 2 are of my 1st 4.0.

There are more pictures in my build thread. Here

 

[alwaysFlOoReD]

There is a single wire to hook up for the tach. The signal did come from the TFI. On the 4.0, it comes from the EDIS. That wire is part of the BWP.

Here are a couple pics of my latest engine. I put it in in May last year.

These 2 are of my 1st 4.0.

There are more pictures in my build thread. Here

Looks like the first 2 pics are duplicates.

 

[SenorNoob]

Looks like the first 2 pics are duplicates.

Fixed. Thanks.

 

[broncc]

I strongly suggest swapping dashes if you don't have year-specific wiring diagrams and a very solid understanding of vehicle electrics. Is 7 bolts holding the dash in. I didn't for color matching reasons and had to spend a lot of time repinning the bulkhead connector.

Off the top of my head the connectors are generally similar with wiper controls and gauges. I recall some exterior lights and ABS being different. Newer ones had more neutral safeties. The plugs on the fender had a different pinout for fuel sending I think.

 

[DPDISXR4Ti]

If your existing harness is on good shape, there might be an easier way. I recently upgraded my 2.9 to run EDIS/MAF using a 4.0 PCM. Even though my 2.9 is in a Merkur Scorpio, the process is still pretty much the same. At this point, I could drop a 4.0 in and electrically I'd need to change nothing. Just a different approach... https://forum.merkurclub.net/forum/viewtopic.php?t=42772

 

[BlackBII]

If you do need the wiring diagrams for a specific year I can post them

 

[DPDISXR4Ti]

If you do need the wiring diagrams for a specific year I can post them

If you happen to have '94 Ranger and '95 Explorer, that might be helpful. Both are the final year of EEC-IV for each of those models. (Note, Ranger jumped a year early to EEC-V in 1995).

 

[BlackBII]

I need to go through and label all the images and post them all in a thread. Maybe I'll do that today


1995 Explorer

1994 Ranger

Non Cal

Cal

1987