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1990 Bronco II, 4.0 engine swap.....Help


pjksr1955

New Member
Joined
Mar 5, 2009
Messages
2
Vehicle Year
1990
Transmission
Manual
I have a 1990 Bronco II with a manual transmission. I purchased a 1994 4.0 engine with wiring harnesses and computer. Engine and transmission is in truck. I need to know what to do electrical. Please HELP.....thanks
 
plug it in.

The 90 is pretty much a direct plug'n'play for the 4.0, assuming you came up from a 2.9L.
 
I took one out of a 93 Ranger and I wound up building a container for the ECU on the drivers side out of a metal fuel can.Start at the dash which should plug in and work your way around till you get to the heater controls.Get most of it all together like the dash and injector plugs then work out like windshield squirter at the end decide if its easier to move wiring or the tank.I really think that not cutting main wires like ecu wires is the best way for long term reliability.
 
The ONLY 4.0 swap that will be 'plug and play' will be a '90 BII 5 speed to a '90 Ranger 5 speed, both will manual windows. Ask me how I know. :D

Even then, I had issues with Wipers, Taillights, reverse lights, Radio.....

Nothing will be 100% plug and play. But a '90 BII to a 90-92 Ranger or a 91-93 Explorer will be easiest of all the swaps. There will always be wiring differences that will need to be sorted out. Get a wiring diagram for both vehicles and start swpping pins on the cannon plug on the drivers side firewall, there will be differences.

You swap the entire engine bay, from the cannon plug all the way around to the passenger side, through the firewall and into the computer. Swap it all over.
 
well that little speach right there killed my swap for me.... plus working on these little fords is driving me crazy.... id rather work on my dodge cummins
 
I did the Bronco 11 engine swap to a 4.0, 5 years ago...

The Swap was not that hard. If you still need my input, e-mail me and I can still walk you through it. It works fine. Justcoffee
 
Go For It

I have a 1990 Bronco II with a manual transmission. I purchased a 1994 4.0 engine with wiring harnesses and computer. Engine and transmission is in truck. I need to know what to do electrical. Please HELP.....thanks

I did this, and was a no brainer...Justcoffee...
 
doing a 4.0 swap into an 89 BII swap now...what did you do at the heater plug ?
Mark
 
doing a 4.0 swap into an 89 BII swap now...what did you do at the heater plug ?
Mark

Heater plug?

Care to explain the issue you are having a little further?
 
Seems that the heater motor draws power from the relay box on the new harness, instead of the fuse box on the original Bronco II harness...in the tech forum write up they talk about having to splice 4 wires for the heater to work but there is no detail about this...just wondering what works here...I have both heater harnesses they are very similar except for the incoming power wire on the newer one. I have an 89 BII and am using a 92 ranger harness...& 4.0 motor and m5od.
 
Not completely shure of your 89 wiring just yet even though I own one. I just completed a 4.0 swap on my 88 and just used the factory heater harness since it wasnt removed during the swap anyhow. The 88 as you stated on your 89 draws its power from the fuse box under the dash and all the wiring for it is inside under the dash except for the small amount of it that plugs into the heater fan and such. Since I retained all of the "dash" wiring all I had to do was provide power to the fuse box under the dash by hooking it to the new power distribution box that came from my donor explorer harness. This winds up giving you an extra form of protection in the way of a second fuse in the distribution box. However, I know for a fact that your 89 had a distibution box from the factory so I suggest that if using the donor distribution box just connect up the dash harness power to the new distribution box in the same place as the donor was hooked up. All should work then.
 
That's what I'm going to try first, just plug in the original stuff and see if it works...If it doesn't it appears the difference is only that the power wire that plugs into the resistor plug on the newer harness comes from the distribution box instead of the fuse box under the dash.
 
The ONLY 4.0 swap that will be 'plug and play' will be a '90 BII 5 speed to a '90 Ranger 5 speed, both will manual windows. Ask me how I know. :D

Even then, I had issues with Wipers, Taillights, reverse lights, Radio.....

Nothing will be 100% plug and play. But a '90 BII to a 90-92 Ranger or a 91-93 Explorer will be easiest of all the swaps. There will always be wiring differences that will need to be sorted out. Get a wiring diagram for both vehicles and start swpping pins on the cannon plug on the drivers side firewall, there will be differences.

You swap the entire engine bay, from the cannon plug all the way around to the passenger side, through the firewall and into the computer. Swap it all over.

I disagree, if you get a 90 ranger harness, its completely plug and play. Other than making it fit to my SOHC, the harness itself is untouched and everything works perfect for me...
 
I did the Bronco 11 engine swap to a 4.0, 5 years ago...

The Swap was not that hard. If you still need my input, e-mail me and I can still walk you through it. It works fine. Justcoffee
lol whats that email. 1990 Bronco II 2.9L to 4.0 swap in progress.
 

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