Today I performed the Post-Nutter Bypass Wiring Removal (PNBWR). This procedure generally involves removing the wiring that is left behind and unnuecessary after performing the nutter bypass.
After you have performed the Nutter Bypass or you spend any time under the hood, you may notice that there is an array of vaccum lines, sensors, and wiring that creates quite a bit of clutter. Much of that can be removed after performing the Nutter, because there is no longer any need to gather data and feed it to the computer (ECM).
If you've performed the Nutter but haven't dug into the sensors and vaccum lines, I suggest you read this post to get an idea of what to remove before you tackle the wiring:
Once you've got the unnecessary vaccum lines and their associated sensors removed, you'll be left with several wiring connectors that lead to a lot of wire. THis wire generally connects back to two places: The computer, which is located above the heater box behind the dashboard, and the yellow diagnostic connectors which are on the passenger side of the battery.
Why remove all of the wiring? To clean up the engine compartment and potenteially make troubleshooting electrical problems a bit more simple in the future.
Here is one other post that has some helpful information about wiring removal after the Nutter. I credit this post for giving me the motivation to go through with this project:
Note that you could complete this process in a far diffrent manner. My goal was to remove one wire at time in order to avoid cutting anything that was still necessary. I took a very precise approach to this procedure.
--- The procedure ---
Note: This assumes that you have performed the Nutter Bypass. It is helpful if you have also removed the unnecessary vaccum lines and sensors, so that you're left with wiring connectors that don't connect to anything.
First, you need to disconnect the computer from the wiring harness. This easiest when you have the heater box out.
Be sure your engine starts and the Jeep operates correctly (lights, etc) immediately after removing the wiring harness from the computer.
As long as you have done the Nutter Bypass, the computer should not be needed, but start the engine and make sure things are working after you disconnect the computer from the wiring harness. If you have a problem at this point then you can plug the computer back in.
Here's the wiring that goes through the firewall to the computer:
Here's a shot of my '85 before the wiring removal:
Here's an alternate shot:
After you remove the two screws holding the black oblong firewall grommet in place, the large connector that connects to the computer will fit through the firewall hole, as shown here:
Next you need to remove the 2 screws that hold the diagnostic connectors onto the battery tray. Here's a shot of that, although in this photo I have already removed it and am just holding it in place:
Next you need to remove all of the split loom tubing covering the wiring across the back of the firewall. You may also need to remove or cut tape and any nylon ties that might have been added. The goal is to get access to the wires.
Here we see the mass of wiring from both the diagnostic connectors and the computer harness:
My goal was to save this piece (which I am calling the Firewall Grommet) so I could cover up the firewall hole when I was done. Rather than cutting the piece up, I slid the wires back through it, one at a time:
The heart of the procedure is this:
1) Locate a wire in the wiring harness that you can slide freely through the firewall grommet, and trace it back to the computer connector. The more wires you remove from this, the easier it will be to get to some of the wires that are sealed into the rubber.
2) Clip that wire at the computer connector and slide the wire back through the firewall grommet.
3) You may discover that your wire connects to a same-colored wire on the diagnostic connectors. If so, clip the wire to free it from that connector.
4) Once the wire is free from the connectors, pull it free from the bundle and pull it over to the driver's side of the Jeep. You may need to feed it back through a few more wires. Lay it over on the side of the Jeep, as seen in the next photo.
5) Start the engine up every few wires to make sure you haven't broken anything. Make sure the wires will not be tangled in the fan or belts.
6) Working one wire at a time, repeat steps 1 through 5.
7) After you've removed all the wires from the computer and diagnostic connectors, you should have a bunch of wires cascading out of the engine compartment on the driver's side.
8) Trace each wire back to whatever it is connected to. You will find that many black and red wires all tie together. I would clip off one wire at a time just to be safe. Other wires tie back to connectors that went to sensors that you no longer need. You'll have to use your brain on some wires and make the call about what to do with them.
9) The wire going to my carburetor's electric choke traveled through a 6 pin flat connector. I cut the wire from the connector and soldered it back together.
Here are the connectors free of wires:
Finally, here's the mass of wires and debris. I weighed the removed wires and connectors and they were 2.25 pounds.
After cleaning things up and putting the remaining wires back into a split loom tube, here's what I ended up with:
Here's an alternate pic:
Finally, here's a before and after photo:
If I could do it again, I would buy some large and medium split-loom ahead of time. I had to re-use some of the tubing that I removed and it would look better to have used a single piece of new tubing.