4.0 conversion on 87 bronco ii

[brando-commando]

alright so i did my 4.0 conversion on my broncoii i got the whole under the hood wiring harness out of my donor vehicle (1993 explorer manual) an i would like to keep my stock dash but im having a hard time doin my wiring for everything and dont quite understand some of the wiring pictures people have used in the tech library fir the conversion can anyone help me out here?

[Shran]

Wiring diagrams are confusing. Just keep in mind that the diagram doesn't look anything like the actual harness. A lot of times, what is marked as multiple wires in the diagram (ground and common positive wires, usually) are actually one wire that has others spliced into it at certain points. Best thing I can say is, pull off all the plastic loom, and go through your diagram and identify every wire, starting at the ECM connector. Then just figure out where they are supposed to go, and match them up with the proper wires in your dash. Good luck.

[brando-commando]

thanks alot for the info i really apreciate that. i mean i dont use any of my gauges in my das anyway besides the fuel gayge but the rest are all aftermarket and i can wire all that in im just having troubles on whit wires to splicefrom my 2.9 harnes to the 4.0 harness to get it fired up.. i tried just about all i can think of and im sure im still doing something wrong all my dash indicater lights come on but no click from the silonoide

[kunar]

double check the trans switch or clutch switch. when i did my swap, i had the same exact problem.

[brando-commando]

sweet thanks i got power to the silonoid and it clicks i just dont have power to my fuel pump i got it all wired in but on most of these 4.0 swaps ive been reading it says to ground a grey/yellow wire at the end of the 4.0 harness thats a 2 pin black plug and i cant find this plug in my harness i have found a grey yellow in a 8 pin plug.. but still no power this is where im lost..

[Shran]

Could very well be another color wire, probably just have to look at the diagram for the exact donor you used, and the diagram for your '87... compare the two and make sure you got the right wires spliced.

[brando-commando]

ill deffinatly try that ive got power to the eec but no power going to my fuel pump and i cant hear the relays come on so idk what wire would turn them on they have power going to them also but wont turn on

[brando-commando]

ive got it!!!!!!!!!!!!! had to run a wire from the power on my ignition to a red wire on the end of the 4.0 harness and it gave me everyhting all power to fuel pump computer and spark thanks for all the help guys!

[84bluebronco2]

Originally Posted by brando-commando

ive got it!!!!!!!!!!!!! had to run a wire from the power on my ignition to a red wire on the end of the 4.0 harness and it gave me everyhting all power to fuel pump computer and spark thanks for all the help guys!

Good to see you kept plugging away and got it! Congratulations on your new 4.0 BII!!

[brando-commando]

oh im lovin it test drove it for the first time tday the 2.9 is garbage compared to the torq this thing has!!!

[lchappyjr]

im doing an 87 bronco II as well, can you help me out on wich wires go where between the harnesses please. I am welding the 8.8 stuff in now and the wires are the last piece of the puzzle.

[AllanD]

I managed to convert my 1987 Supercab Ranger to a 1993 Explorer Engine with
as much of the explorer underhood wiring as I could manage.

My objectives were to use the underhood "Load center" and get RID of
all those DAMNED fuseable links and replace them with fuses.

the first stage of the wiring work required four saw horses and two half sheets of plywood
I layed out BOTH harnesses on their own makeshift table

Because I was keeping the original grille and lighting I started by splitting the loom and
dismantling the 1987 harness to preserve the lighting wiring.


I then removed the lighting wiring fromthe 1993 harness and "merged" the two harnesses.

ALL my "splicing" is in one area that I could literally fit within the wrapper for a king size Baby Ruth bar.... because ALL my splices hide between the inner fender and the 1993 washer reservoir/coolant bottle.

I avoided many splices by disassembling the connectors for the 1993 harness and inserting the pins into the 1987 connector shells.

The connectors coming out of the firewall (as you know a 1987-88 doesn't use a single "big round plug") were except for wires added to the "engine side" and additional wires that were added for various reasons the "body side" of those connectors were left alone.

To do this takes proper documentation, which means NOT the wiring diagram
(which is bizantine in it's complexity) but the EVTM manuals for BOTH the donor and recepient, time patience and a methodical nature.

My wiring took me all of the good weather days of three weeks in August, 2007
(interruptions by thunderstorms were frequent), but I should not I checked and rechecked EVERYTHING multiple times then walked a friend through it wire by wire in individual circuits before that circuit was awarded it's fuse for testing.

When time came to actually turn the key we had a problem, ONE ground screw next
to the PCM was not tightened and this caused the EEC power relay to not power up.

Once that correction was made the engine fired and everything, and I mean EVERYTHING
worked perfectly...

Actually truthfully one thing didn't work still doesn't work and I have not even
tried to fix it since the late spring of 2008 because I simply stopped caring...

What is that one thing? The wide open throttle relay that turns off the AC at full throttle.

I should not that through this I also wired in dual fuel tanks to full factory functionality, added 1994 factory AC (yes, on my 1987) and created a "hybred" cruise control system that still works perfectly.

I say "Hybred" because the parts under the hood are all 1993, but the electronics and control switches are all 1987-88

The one annoying thing? sometimes aged wires have changed color due to age
and are harder to identify because (for instance) light blue has aged and yellowed to medium green... or black has faded to brown.... This stuff will drive you nutz.



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