Well, I just spent the night in the garage doing the Nutter bypass on my 85 CJ7, which gets rid of the ECU. Everything went fairly smooth, and when I was finished the Jeep started and ran fine. Fortunately, the carb already had the stepper motor unplugged, and the carb tuned. The ECU was doing pretty much controlling nothing anyway so I got rid of the hole mess.
It was hard to believe the amount of excess wiring I was able to get rid of by do this procedure. I disconnected the Neg. Battery cable, and I worked from the inside out. I took the dash panel and slid it back and let the right side drop down. I unscrewed the speedo cable which let it drop really low to access the ECU. I unscrewed the electrical connector then the ECU itself and laid it aside.
I then opened the hood and unscrewed the fire wall grommet the housed the wires that went to the ECU. Next I unscrewed the the diagnostic port from its mount beside the battery. I then manuvered the harness to where I had good access to deloom it. Once deloomed I found the twisted orange and purple wires and traced them to their origin, the ECU plug end, and snipped the wires. I then went to the drivers side of Jeep and traced the orange wire going from the Ignition box to the ECU, and snipped it off. Once these were snipped I marked them and manuvered them out of the way.
Then I began the process of tracing all the wires from the ECU and DIagnostic ports and pulling the ECU and Diagnostic port wires from the passenger side of vehicle. There were three ground wires on the right side of engine and all were snipped at the block which allowed the harness to be pulled to the driver side of Jeep. There was some juggling and a couple other wires that had to be cut to get the harness to the drivers side.
Now on the drivers side things got scarey. I was uncertain if I was going to clip a wire that shouldn't be cut, but all went well. I unplugged the O2 sensor wire and a wire that was on top of intake and in front of carb. There was a 6 pin square, 2 pin Square, and I think a 4 pin square connector that was not plugged into any thing and attached to the ECU harness. I pulled those out as best I could and found I had to clip some wires that was on a 6 pin flat connector. Once that was done and a ground wire snipped the whole ECU harness came out. I left a few inches of length on the wires I snipped off of the 6 pin flat connector in case I messed up and had to patch up a mistake. Also, there was a funky little plastic casing that had wires going to it from the 6 pin flat connector and some that went to the ECU I left them alone for the time being.
With the ECU and its wiring off the vehicle I began to do the By pass. I had purchased new wire looms because the old stuff was brittle and was falling apart. I started at the distributer and taped the orange, purple, black, and green wires to make the looming process easier and to tiddy the harness up. I taped every 6 inches or so till I got close to the end of the twisted purple and orange wires. I then unbolted the Ignition box on the drivers side fender under overflow tank. Access to the bolts are under inner fender. I then disconnect the harness and straightened it out and deloomed it. I then stripped the Purple wire at the Ignition box, and cut a piece of purple wire from the ECU harness which I tossed aside. I spliced the piece of purple wire into harnsess at the Ignition box purple wire, and then soldered it together and taped the connection. Then I began taping every 6 inches the harness from the ignition box to meet in the middle at the harness coming for the distributer with the twisted orange and purple wires. Once there, I cut the excess wire off and slipped on two pieces of heat shrink tubing spliced purple to purple, orange to orange, soldered, heat shrinked, and taped. Before I soldered these connections, I did test start the Jeep it started and it ran fine.
With the Jeep running fine, I then proceeded to reloom the harness. I took off the 2 vacuum things off the fire wall and put the screws back in the holes they came out of and removed the old wire ties I cut to pull the harness out. I placed new zip ties and started from the driver side. I ran the Ignition back to the fender with its wiring in a clean manner and reattached ignition box to inner fender. I have a manual trans so the wires are close to the cluch linkage. I made sure to secure newly loomed wires in such a fashion that the linkage would not rub wires. I worked my was across securing loom to the fire wall and around to the passenger side of Jeep. Once completed I then decided to start Jeep and test for voltage that that funky little diode box. There was none so it was cut away from the harness and tossed. I then cut the extra wire that went to electric choke, leaving one wire on the choke connector. I then checked for voltage on the loose wires at the 6 pin flat connector. Two Reds were hot the rest were dead, all wires were trimmed at seperate lengths and taped and then the 6 pin flat was secured to the fire wall. With all wires spoken for and secure I started jeep and let it warm up everything still worked properly. Jeep shut off. I cut the ECU harness at connector to get the big rubber grommet of and reistalled it on the fire wall and plugged hole where the previously removed wires went through. I then I snipped any wiring on the engine that was now not in use, due to the Nutter job, tiddied the engine bay up, and tied up any loose ends and closed the hood. Job complete underhood. Reinstalled dash panel and speedo cable and Job done. Cleaned area up and came and wrote story.
All in all it took about 4 hours to do it. I could do the next one in 2 hours. It sure helped declutter the engine bay. If the ignition goes south sometime in the future I will declutter some more with a Davis Unified Distributer.
I work nights, so it was fun to work on the Jeep overnight, rather than do real work. I also put on new heater cables and Heater switch as well. I thought I was going to have to pull the whole heater out and do a complete overhaul, but a little WD 40 and some moving of all the levers and it all loosened up well. I have to adjust the vent door on the passenger side to get it to close properly but other than that, I am almost ready for winter.