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

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 the red thing in the middle by picking at one of the middle 4 pins. You’ll see the holes in the red thing in the picture below.

Then use a pick to press the little tab about half way down the pin towards the middle while pulling on the wire. Be easy on the tab because they break easy. Practice on a plug your not using. Then put the wire in the correct spot and press it back in. You hear a click. Then replace the red middle thing.

Here are my wiring note. It has the Bronco II wires on the left and Explorer on the right. It tells you exactly what I did for my swap. Remembering I used the 4.0 engine harness only. Used the Bronco II headlight harness (BWP Big White Plug) and the Bronco II dash. So the problems came on the passenger side where the 4.0 engine harness meets the Bronco II headlight harness.

Click on the image above to enlarge or click HERE to view it as a .pdf document

Remember each swap is a little different depending on what you are using. You NEED the wiring diagrams for both vehicles. The diagrams are really easy to use once you figure out which plugs are which on the diagrams. Just trace wires to where they go and then find the partner. Most of them are color coded the same from vehicle to vehicle but they go to different plugs, so you splice. Sometimes they go to the same plug but not the same spot, they don’t match up. So you swap pins. There are a few colors that changed over the years. You can find them from my word document. There is only a couple I think.

Also there is a black and light blue one that is for the temp sensor. On the Bronco II it went through the trans harness and up to a plug and into the dash. On the 4.0 it goes on the engine harness over to the pass side and then to a plug by the battery and the around to the drivers side and into the dash. The plug by the battery is a 4 pin plug. The Bronco II side only has 3 wires and the 4.0 side has the extra one. Pull the pin on it and run and wire and splice it to its buddy on the drivers fender.

I used the 4.0 EEC harness. Use the original Bronco II or Ranger, headlight harness (big white plug harness) unless you are swapping dashes. Then use all 4.0 stuff. So the problems (which my word document covers) are between the connections of the engine harness and the headlight harness since they are different. You will also need the 4.0 starter harness, battery cables (grounds included) along with the alternator harness. The alt. is part of the headlight harness but since the alt. is different you need to splice. There are 2 wires that do not matter and 2 that you have to splice. When you get to this step, let me know and I can get the colors for you and tell you exactly what to do.

Do not remove the headlight harness from you truck. Use the original Ranger/ Bronco II headlight harness. Use the 4.0 engine harness. Cut the wires that go to the 4.0 alt. off of the donor’s headlight harness. Then cut the same wires off of your headlight harness. Splice them. I’ll get the colors for you. Not sure what you mean by remove the cover off the headlight harness. Other than the alt. wires, do not touch the headlight harness.

The ideal way to do it would be to swap all in from the 4.0 (engine harness, headlight harness, dash) then all matches up and should have no problems. I however did not want to swap my dash so I did it this way.

If you do it this way using the Bronco II headlight harness you will not have DRL’s (if all ex’s had them?). Your lights and whatnot will function as they did before. You do not need any of that stuff. It is way more work to swap the Explorer headlight harness in. If you wanted to you could put the Explorers headlight harness in but then the trouble would be at the big white plug. Very little matches up and would be more work. So just leave your Ranger headlight harness in. Then the splices will be between it and the ex’s engine harness on the drivers fender. Basically put the engine harness in and hook everything up that you can. Leave your Ranger headlight harness alone. Then follow my word document (image / .pdf above) for the ones on the drivers fender. You will be able to look at the plug color (grey or black) and the color of the wires to find out which plug is which. Put a temporary piece of tape on the plug with the number of the plug on it for easy reference. Or on the grey plugs just use permanent marker to put the # on. The #’s come from a book I had. The 2 119’s are both from the ex. This goes to the trans. Plug em in. The 2 117’s go together. Plug the 116’s together. Plug 101’s together. Plug #’s 136 and 122 in the end will disappear. They did on mine anyways.