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Wiring difficulties after engine swap

2K views 27 replies 5 participants last post by  standtall99 
#1 ·
Hey whats going on guys my name is mike,i have a 1996 project bronco i have been working on for a little while now,i am a new mechanic and do not know too much about wiring etc.
So what my and a friend did is take a ford 302 5.0 out of my 1993 bronco(which rear died) and took the old motor out of the 1996 one,which was a ford 351w but just the block,in order to put the 302 into the 1996,all went well is is hooked up to the tranny all vacuum lines are hooked up and mostly everything else, the problem we ran into is we were going to leave the wiring harness that was on the 302 and use the same computer that the 302 has been using,but the plug for the computer did not match up, so what we thought of doing then was changing the wiring harness to the harness that i had from the 1996 351 so we can use the stock computer for the 1996,but not all of the plugs from said harness match up to the plugs on the 302.
So as of now we have the plugs that did fit onto the 302 from the 351s wiring harness hooked up and the 351 computer as well.

My question to you guys after that long run on of a story is this, where can i get or can i get a wiring harness that will match up to all of the plugs on a ford 302 and a computer that will also match up to the 1996 s computer plug.But have the right firing order for the 302.

Please bare with my non technical terms,i am very new to mechanics.
 
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#4 ·
You're 302 is from an OBD-I, I'm assuming it's MAF, and the the engine/harness from your '96 is an OBD-II, completely different. If it were me, I'd just take the harness and EEC from the 302 and call it a day.

That was my original plan, but the plug that is on the 96 does not fit the 93s eec properly so thats why i switched over to try and use the 96s eec and wiring harness.
 
#5 ·
Couldn't remember if they switched in '93 or '94 on the 5.0's.

Can you clarify some information:

You have 302 (OBD-I) in the rig now
You put it in a rig that had a '96 351 (OBD-II), keeping the main chassis harness and EEC from the '96

I'm guessing when you pulled the 302, you kept the injector harness and everything that was attached to the 302 motor, is that correct?

Whatever the case, the EEC from the 351 won't work that 302, which is why in my original post I said to take the stuff from your 302, harness and everything and use it. The injector harnesses are very different.

If your 302 engine was MAF it would be pretty easy, just swap the harnesses and EEC.
 
#7 ·
Ok,i do apoligize as i believe i am talking solely about the injectors wiring harness and not the wiring for the entire truck. I am very new to all this and appreciate you decoding this all for me, what i wanted to do is put the 93s computer into the 96 and use the 93s injector harness as well,but the problem with that is the main connection does not suit the 93s computer so thats why i tried using all the 96s stuff (computer,inject harness) but only the injector plugs matched, and thats where i am now,with the 96s injector harness and the 96s computer hooked up with only half the plugs connected.
 
#12 ·
It's really not all that difficult. Takes some time and patience, but it is pretty straightforward.

You start at the firewall and disconnect the EEC and other main connections, you'll need to remove the power distribution box, air box and bracket as well as the washer reservoir. The rest is easy, there are a couple of bolts for ground and tabs that hold it to the core support. Trickiest part is pulling the long section of harness from behind the radiator, but once that is out you're pretty much home free.

I've removed the harness at least 4 times on my rig, trust me you can do it. If you have questions just post up here and either myself or someone else will be happy to help.
 
#15 ·
Im not overcomplicating anything,whats a problem to some may seem easy to others.
But @ jermilo i just took the entire wiring harness out of the donor truck and will be taking the wiring harness out of the white one tomoorow,thank you for the idea and help,it wasnt too hard at all.:thumbup
 
#14 ·
run all the 96 wiring on the 93 5.0 motor. most everything should work. the 96 5.8 computer should also run the 5.0 just fine. OR just sell that motor and find another 96 5.8 from a bronco or an F150 and bolt it in and wire it up.

i think your over complicating this.
 
#16 ·
the 96 is a stand alone year. you cant just swap the entire harness's between rigs and expect things to work properly.
 
#17 ·
:stupid
 
#18 ·
Okay,so i would stick with all the 96s wiring to the 302 but some plugs on the injection harness dont match up to those on the 302,what should i do ? I cant afford,in money or time to swap out motors, can i get someone to splice wires and make the plugs fit? Or maybe buy an after market harness somewhere that would help me? Thank you for the feedback and help i do appreciate it all,mike.
 
#19 ·
Just to be clear, he's putting the 302 in his rig that had a 351, so the 351 isn't even in question, other than he wanted to use the EEC from it and keep the chassis harness which will not work...If he simply carries over the injector and chassis harnesses as well as the EEC from the 302 he won't have any issues.

If you want PM me with your contact info and I'll give you a call.
 
#20 ·
what plugs are not matching up? there will be a couple perhaps like the 93 302 is missing a crank position sensor which can be pulled from the old 5.8 and swapped over. that 93 5.0 will have a knock sensor that wont have a home on the 96 harness. the sensors from the 5.8 can all be swapped over to the 5.0.
 
#21 ·
Alright so what do you guys think is better im down with doing either,and all the injector plugs from the injector harness fit but most other dont like the plug for the throttle body and most plugs besides the actual injectors,should i stick with the 351s wiring or put the 302,my question to you is will it work? if i just put all the 302 wiring in there and what might not work?
 
#23 ·
the throttle body from your 96 5.8 can be installed onto the 93 5.0 motor, that takes care of those plugs. get the tone ring off the 5.8 crank along with the crank position sensor moved over to the 5.0. the powersteering bracket and ac bracket will transfer over from the 5.8 to the 5.0 if necessary.

I honestly feel you should leave the 96 harness in the 96 and get the 5.0 in. YOU CAN DO THIS
 
#24 ·
Hey i looked all my parts from the 96 over and i dont have the throttle body or the ac,when i got the truck i only got the block of the 351 and some spare parts such as the alternator and starter etc,but of course not the ones i would need haha,so i am going to have to put the 93s wiring in there,im going to be doind it now il take pics and let you guys know if i have any trouble and how it goes,thanks alot.
 
#25 ·
Okay so i switched the wiring harness,the injector harness,and the 302 computer,All lights go on including headlights flashers so powers deffiantly going through the harness,but i can get it to turn over and i think it has something to do with this one wire that didnt match up by the power dist box,i think it may be the ignition wire? The starter doesnt click or make any noise at all,any ideas on what could be going wrong and what should i do ?
 
#28 ·
Okay,so i got the new relay on and its hooked up correctly,my local mechanic had me test the relay and the starter by hooking up jumper cables from the relay to the starter too see if it would crank over,and it did,i checked all of my fuses everywhere,that are visible,and a couple of them were shit so i replaced them,but i still cant seem to get the starter to turn over when i turn the key,is there an ignition wire and if so where is it?And is there anything else i could check or replace? Thanks alot guys,mike
 
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