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Unread 08-28-2010, 02:45 PM   #1
Ken4444
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Post-Nutter Bypass Wiring Removal

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:

http://www.jeepforum.com/forum/f8/va...ypass-1047507/

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:

http://www.jeepforum.com/forum/f8/wi...utter-1064769/

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.

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Unread 09-01-2010, 10:16 AM   #2
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Just a brief update: So far so food. I haven't had any problems since the wiring removal. I'm hoping to pick up some new split loom tubing today to replace the recycled pieces I used originally.
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Unread 09-04-2010, 11:31 PM   #3
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This is very good, thanks. I am going to be removing a bunch of this stuff very soon.
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Unread 09-05-2010, 02:36 AM   #4
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Great thread Ken, the pictures help a lot. Question, I keep hearing that some tail light wires run into that grommet with the computer wires. Did those wires connect into the computer terminal or was that just where they pass through the firewall then split off?
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Unread 09-05-2010, 06:55 AM   #5
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Quote:
Originally Posted by kakai81 View Post
Great thread Ken, the pictures help a lot. Question, I keep hearing that some tail light wires run into that grommet with the computer wires. Did those wires connect into the computer terminal or was that just where they pass through the firewall then split off?
In my '85, there were no other wires going through the firewall grommet. The only wires that went through the grommet went to the computer. Of course every Jeep seems to have differences somtimes.

If you follow the procedure wire by wire, working one wire at a time, you will easily be able to identify all of the wires that connected to the computer and the diagnostic connectors. Because these wires don't connect to anything essential after you have done the Nutter Bypass, you can remove them one by one.

When you run into a wire that connects to something else that traces back into another bundle of wires, clip off the dead wire (that went to the computer or a sensor, etc) but make a note of the remaining wire. You may need to seal it off or make a note to investigate it later. Be sure to check the basic electrical functions at that point (jeep starts, lights work, etc) before proceeding to the next wire removal.
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Unread 05-06-2011, 09:00 AM   #6
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took about 45 minutes! nice real nice.
p5060322.jpg  
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Unread 05-06-2011, 09:06 AM   #7
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Here was my pile!
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Unread 05-06-2011, 09:33 AM   #8
Ken4444
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Originally Posted by littleturner76 View Post
took about 45 minutes! nice real nice.
Excellent. I'm glad a few folks have found this thread. I think the 258 can be made to run efficiently and clearnly without the feedback system as long as the PCV, EGR, vacuum, and charcoal cannister parts are all connected correctly.
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Unread 05-06-2011, 09:50 AM   #9
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Think it will do it minus the EGR as well.
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Unread 05-06-2011, 09:54 AM   #10
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Think it will do it minus the EGR as well.
I've done some reading on keeping or scrapping the EGR and I have seen arguments on both sides of the fence. I'm generally in favor of sensible pollution controls and a properly functioning EGR valve makes sense to me. Removing it and capping off the ports shouldn't cause any problems with the engine though.
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Unread 05-19-2011, 07:21 PM   #11
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so here is what i have. i got a little to happy and cut a few too many. now im not starting. it does sound like the solenoid is clicking, but nothing else. check out the pics............[IMG] [/IMG]
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Unread 05-19-2011, 08:13 PM   #12
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Quote:
Originally Posted by kakai81 View Post
Great thread Ken, the pictures help a lot. Question, I keep hearing that some tail light wires run into that grommet with the computer wires. Did those wires connect into the computer terminal or was that just where they pass through the firewall then split off?
All of the tail light, back up, interior hard top light wiring, and I believe the fuel gauge sending wire, is inside the tub next to the body, under the lip.
If you were to look at the fuse block from the firewall side, there is a bolt holding it to the inside. Everything on the right side of the bolt are headlights, parking lights, horn, and windshield washer. The two bottom black wires are the brake warning light that go to the proportioning valve.

On the left side, among other things are the 4wd light switch wires, temp and oil pressure, and back up light wires from the tranny. Ignition module, starter solenoid , 12v feed for everything under the dash. The only wire I'm not sure about is the excite wire from the alternator.
Ken, great write up! When I did mine, I had also nuttered and teamrushed, with the GM IGN module. So I just started cutting, after taking the loom off.
Bill
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Unread 05-19-2011, 08:44 PM   #13
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Originally Posted by WesleyNowlen View Post
so here is what i have. i got a little to happy and cut a few too many. now im not starting. it does sound like the solenoid is clicking, but nothing else. check out the pics
If the solenoid is clicking, but the engine isn't turning over, then it should be pretty simple to troubleshoot, or at least to start troubleshooting. Find the FSM for your year or pick up a Chilton's manual and find the schematics. The wiring in this area isn't too complicated. When the solenoid clicks, then it should be supplying power almost directly from the battery to the starter. So, the problem may not be directly related to the wiring removal.

I saw in one of your photos (below) that it looks like some wires were cut at/near the driver's side firewall connector, which does not seem right.

When I did my wiring removal, I did not pull any wires from this connector. Some of the wires got near this connector, but not as close as I'm seeing in your photo.

Did you cut any wires that were going directly through the driver's side firewall connector?

The larger gauge red wires should almost certainly carrying current to multiple and/or important things.

Also, did you stop your work and start the engine after removing each one or 2 wires?

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Unread 05-20-2011, 08:04 AM   #14
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[QUOTE=Ken4444;11572168]If the solenoid is clicking, but the engine isn't turning over, then it should be pretty simple to troubleshoot, or at least to start troubleshooting. Find the FSM for your year or pick up a Chilton's manual and find the schematics. The wiring in this area isn't too complicated. When the solenoid clicks, then it should be supplying power almost directly from the battery to the starter. So, the problem may not be directly related to the wiring removal.

I saw in one of your photos (below) that it looks like some wires were cut at/near the driver's side firewall connector, which does not seem right.

When I did my wiring removal, I did not pull any wires from this connector. Some of the wires got near this connector, but not as close as I'm seeing in your photo.

Did you cut any wires that were going directly through the driver's side firewall connector?

The larger gauge red wires should almost certainly carrying current to multiple and/or important things.

Also, did you stop your work and start the engine after removing each one or 2 wires?

Unfortunatley it was too late when i decided to try starting the engine. I realized that some of the wiring i cut didnt seem right, and thats when i stopped. Still havent had a chance to look at it, its driving me nuts, i know its nothing major and i would really like to get back on it.
I did see in the manual that the black wire from the solenoid looked like it went to the nuetral safety switch in the tranny, maybe that could be it. Or there is a red wire that is cut going the the plug which feeds my electric choke. Thats all i can remember until i get back out there. Thanks
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Unread 01-19-2012, 03:26 PM   #15
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Thanks, helped allot. took all of it out and found out that some one had done this and reinstaled it on my jeep. i also took out the vacuum lines out too. did the nutter by pass of course.
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