Wiring

For the wiring part, I could not find any kind of write-up for swapping a wrangler 4.0 into a wrangler that had a 4.2.  All of the ones i found used cherokee 4.0 motors.  So, after i put the motor together, i realized that nothing but the lights would turn on and i figured it would be a hassle to figure out the wiring.  Then, i found a website that helped me out a lot, since i could not find anything by searching.  Its www.alldatadiy.com and it gives you everything you need for wiring diagrams.  You have to pay a little bit for it, and you can only look at one year of one certain model vehicle, but it lasts a year and it is worth it in my opinion.

     There is a body harness connector that goes through the firewall next to the steering column, to the left of it if you are looking under the hood.  You are going to need that plug.  You will have to cut it off of the donor vehicle so you can wire up the gauges, the starter, and the radio.

     Here are the wires you need out of this plug:

     Red-Constant power for radio/cd player (or anything you want to have constant power)

     For gauges:
     Purple and Yellow-Engine Coolant Tempurature
     Grey and Yellow-Engine Oil Pressure
     Dark Blue-Fuel Level
     Yellow-Starter

     These are the colors of those wires at the old gauge cluster:
     Purple-Engine Coolant Temperature
     Light Blue-Engine Oil Pressure
     Tan-Fuel Level
 
     What I did to connect the sending unit wires to the gauge wires was i used wire to go from the gauge cluster to the connector.  I just cut them at the gauge cluster one at a time and ran them under the dash.


     The yellow starter wire will splice into a dark green wire that is in the connecter that is on the upper side of the steering column, under the dash.

     Also, for the fuse box that is for the 4.0 motor, i just mounted it onto the side of the original battery mount instead of putting the newer style one in there, which puts the battery parallel with the firewall and the fuse box in front of the battery.

 

      After doing this, i was able to start up my Jeep and drive it with the new motor.  It was a lot easier than i had expected.  If you use a Cherokee motor, you have to tear apart the bulkhead connector which is to the right of the brake booster because a few of the wires are in different spots on the Cherokee.