Need help with swap wiring.

[David Nelson]

My project is 1987 Ford B2. I purchased this B2 with the 97 Ford Ranger 4.0l 4x4 engine and trans and transfer case installed. The previous owner had a family member start the project and like myself was over his head when it came to the wiring part.I thought I could figure t out with some reading and common sense. Well I had to walk away from the project early fall last year it was making me crazy. Now that it is starting to warm up a little I'm going to attack it again. I read this and that article one person will say this another will say that. One thing I have come to realize is the 97 engine is a lot harder project than the early 90's engines due to the OBD2 system. The B2 has a interior power distribution box (fuse box) I'm using it due to it already has the all of the lights and interior things on it and the all work. So I'm down to the running gear. The 97 engine has the starter on the drivers side, so I mounted a new battery box and the starter solenoid on that side. I didn't care about cruise so I took it off. I need to get a throttle cable. I have the complete under the hood wiring harness off a the 97 ranger I removed it myself complete.It has the engine harness intact not molested. The harness has 3 large connectors 1 goes to the engine harness (connected). The other 2 went into the cab via firewall plugs. These ran a lot of the interior stuff, like seats windows doors lights and such. NOT NEEDED. Excuse me there will be a few wires I will need like ignition switch.
My plan is I'm using the under hood PDB and I will pull wires that are not needed to make it run and move. The PCM I mounted on the drivers side fender and it's hooked up to the harness. So here I am what do I need to do to get the engine to turn over and start. The radiator is a future issue, along with the exhaust trans and 4x4 working. That's why they call it a project. Yes I have been here before asking for help. Like I said earlier I have read most of the articles on 4.0l swaps. It good info but the 97 OHV is different alot more complicated to swap than the earlier 4.0l. Thank You Please help if you can. David

 

[adsm08]

There are a couple ways to do this.

Assuming I had two complete vehicles, with all their wiring, I'd start by getting a 90 or 91 alternator (or making sure it's the same as the 97). This will plug into the 87's wiring system with minimal modification to any wiring, and it will work. You will also need to run a large gauge cable from the alternator's B+ post out to the battery or the BJB's B+ bus bar.

Then I'd find the red/blue starter trigger wire coming out of the firewall, and run it right down to the small post on the starter, and run a battery cable straight form B+ to the starter's large terminal, skip the relay altogether. Your ignition switch can handle the load when wired that way.

Then I'd find the key switched powers for the PCM on both sides of the swap and connect them. At this point it should start and run.


I had my 88 B2 wired up more or less that way. It runs just fine with a 93 engine harness with only three or four wires connected between the two.

 

[franklin2]

If he used the complete underhood harness from the 97, that will have the 97 alternator wiring correct or not? And he probably has the 97 alternator still mounted on the 97 engine? If so, he is going to need to mate the 1987 interior harness wire to the correct 97 underhood wire for it charge.

To the original thread starter; Do you have a good set of diagrams for the 97? Do we have a source for these we can look at online? I will check this site and see what they have in the wiring diagram section.

 

[adsm08]

If he used the complete underhood harness from the 97, that will have the 97 alternator wiring correct or not? And he probably has the 97 alternator still mounted on the 97 engine? If so, he is going to need to mate the 1987 interior harness wire to the correct 97 underhood wire for it charge.

Yes, most likely, however with the charging harness being integrated into the engine harness in 97 that is a whole other set of wires that needs to be found, cut, and re-spliced correctly for the charging system to work since he intends to keep the 87 dash harness. In 87 the alternator's wiring was in a stand-alone sub-harness that had it's own plug (may have been two plugs) that came through the firewall on the "root" (the portion of the gen 1 dash harness that sticks through the firewall has about 8 legs and looks like a plant root when held up). These plugs ONLY handle charging system circuits and by swapping one wire into a different cavity of a connector and using the 87 alternator harness the charging system become plug and play.

To the original thread starter; Do you have a good set of diagrams for the 97? Do we have a source for these we can look at online? I will check this site and see what they have in the wiring diagram section.

I have access to the OEM diagrams, but because of how the website they are on is formatted posting them to TRS is pretty much impossble.

 

[David Nelson]

Hello, thx, yes I'm using the complete 97 engine harness to which the 97 alternator is hooked up, So as I understand the 87 is a stand alone system. so I need to find the matching wires and splice. I do have wiring diagrams from several places. I purchased the Ford 97 electrical and vacuum manual which have great diagrams also Haynes wiring diagrams. A lot of my problem reading the diagrams is following which direction the flow is going. I hope that makes sense. I read somewhere that positive is always on the top and neg. on the bottom. Most of the old wires coming through firewall are faded and hard to make out the true color.

 

[franklin2]

Does your 87 Bronco have a dash light for the alternator or do you have a ammeter gauge for the alternator?

 

[franklin2]

Below is the 1997 ranger charging system diagram I found. Do you have all that wiring from the starter relay to the alternator and the underhood fuse box? I would think that would have been part of the underhood wiring you got. And that is all hooked up? If so, you can see all you really need is one wire to come from the 1987 dash, the trigger wire to bring the alternator online to charge when the keyswitch is turned on.

If your 87 used a alternator dash light for the 87 system, you already have the same color lightgreen/red wire under the hood, or wherever it ended up. You will need to track down the 1997 lightgreen red coming from the 97 harness/alternator, and then track down the lightgreen/red from the 87 harness, and splice these two together.

I am assuming you are going to keep the 87 firewall plugs and penetrations, and eventually completely cut out those two 1997 plug-ins?

 

[David Nelson]

My B-2 has the has the light. How do I print the reply's ? Yes I'm going to keep all of the B2 firewall penitratios and splice into the 97 correct.

 

[adsm08]

I read somewhere that positive is always on the top and neg. on the bottom.

Yes, in general Ford wiring diagrams will start with positive at the top and power flows towards ground at the bottom of the page.

There are some exceptions, which should be easy to identify, because they mainly involve a relay where the line representing the wire makes a U and goes back up the page a bit.

If you look at the beginning of the book there should be a page near the front with a key code for the symbols used for the various things like battery, types of loads, and grounds. Any point with a prefix of G, like G100 or G103, is a ground. This is one of the things that Ford really doesn't make difficult.

 

[franklin2]

Below is a older diagram I picked up off this site. You can see along the top right is a yellow wire. This is one of the main feed wires to the older system to power it. Should be somewhat like the 87 has.

 

[franklin2]

Below is another older diagram from this site showing how the yellow wire or wires feeds the ignition switch and it also goes on to feed part of the fuse box for power all the time parts of the underdash fuse box. You need to find these main yellow wires and also the black/orange that feeds the headlight switch in the 87.

 

[franklin2]

You can see in the 1997 ranger diagram below they also fed there ignition switch with a large yellow wire. They also separately fed the underdash fuse box. Both with large 50 amp fuses in the 1997 underhood fuse box. I don't have a accurate 1987 diagram, but if they fed both the ignition switch and the underdash fuse box in 87 with only one yellow wire, you may only want to use one of the 1997 circuits. Like the charge system wire, just find them and splice them together.

 

[adsm08]

 

[franklin2]

If those are 87 diagrams, looks like one single yellow wire. You are going to find it downstream from the 87 starter relay wiring.

 

[David Nelson]

I want to thank you guys for all of the good info. and diagrams. With this I have a lot to digestive and research. I'm going to remove the top and bottom intake to make it easier to trace wires. Thx David