Removal of C-101 Connector (Renix Only)

So, this is my first major thread or anything that resembles a write up. Mind you all of this I did on my 1987 Wagoneer 4.0L AW4 non ABS. I suggest you merely use my technique, not follow this exactly. I cannot factor for all of the variables.

C101 Backstory

The C101 connector is located on the drivers side firewall, above the brake system. The connector is one of those things that are a good idea, but in the end, the execution fell short. After a while, weather gets a hold of it and it starts causing issues with all of the sensors (TPS, IAC, the ground for the MAP, Intake Temp, Etc.) It actually started causing so many problems for the CKP, dealerships bypassed it from the C-101 straight to the the PCM. So rather than pull it off and keep cleaning it, I decided to bypass it all together.

Getting Started

Although I started taking pictures after I pulled the C-101 apart, if you are doing it all at once, you dont have to worry about breaking it.



Before you start cutting every single wire, you need a gameplan. If you end up losing a wire, or miss wiring, it will be a pain fixing it.

My game plan was to start the bypass where the PCM side of the harness comes out of the firewall.





The wires for the most part are color corresponding, but the best and smartest way to make sure that you dont cross wires, is just do one wire at a time. Trace the wire to the C-101 and find the corresponding wire on the PCM side. Snip and tie together. I tied mine together because I am also cleaning the harness up, getting rid of extra wire so i can keep the wires from resting on the manifold.



Progress Shot, This is snipping one wire at a time mind you.



Another progress pic, note that I just tied them because I was also going to shorten the wire up.



If you find duct tape in the harness, do not fret. That is actually from the factory. All of the sensors ground on the same wire. just unwrap the duct tape, and if everything is still shiny, just put some electrical tape back over it. I do however, recommend each sensor run off its own ground, so my plan is later run something similar to a junction box, but a big gauge wire runs straight to the negative battery post. Since this is my DD, I decided to do a little at a time. I didnt do every single wire yet, about 80% done. but once you have everything planned out, either use butt connectors or a soldiering gun and shrink wrap. But remember to be patient. Rushing a wire harness will cause shorts and that "omg my engine is possessed" symptoms. Its definitely not hard, just requires patients. Any questions just PM me. or post here, wherever.

Note from DJ
I have an 88XJ that I have removed the CPS connections out of the C101 connector and shortened the wires on so far. This small improvement in the wiring system has almost put a stop to the no start-raise the hood-unplug-then replug CPS connector and then startup was successful. This is as far as I have gone at this point so was glad to see your write up nice job especially with the detailed photos.

My only suggestion would be to apply so flux and solder onto all of the crimped connections that you expose before you re-tape them with electrical tape, they are only crimped and have a bad reputation for causing increased resistance especially when they are disturbed.

I like the idea of the new grounding system, my thoughts also, but I have not yet come up with clean but efficient plan for this improvement.

I for one really appreciated your taking the time for this write up.

Its no problem. Before my TPS was only getting 4.6V, now im getting 4.99. And that's with my horrible soldering lol. So essentially, the c101 was just adding way too many ohms. All my grounds still had shiny solder on them, so I just put better insulation.

Also as far as the individual grounds, ill add to this thread when I do it.

Nice write up and nice pictures. I still have my C-101 on my 87 Wagoneer!

Most, it not all my problems have been O2 sensor wiring getting to close to bad stuff, like driveshafts and Ex-manifolds, and poor sensor grounds, especially both sides of the TPS.

My C-101 has 278,000 known miles on it.

Last thought, PVC electricians tape is worse than duct tape under the hood, neither holds up worth a damn under the hood.

While expensive, electricians self vulcanizing rubber electrical tape for high voltage work does work well under the hood. I also like the liquid electrical tape in a bottle.

I definitely would like to see this as a FAQ article :thumbup:

I actually prefer thermal sealant filled heatshrink butt splice crimps over soldering in an engine compartment. The thermal sealant does a darn good job and if you use a proper ratchet or hydraulic crimper (not the silly sheetmetal pliers style ones) a crimped connection is every bit as good as a soldered connection, and much harder to do wrong. Either way is ok though as long as you do a good job.

When flexing is involved, I have seen soldered multicore wires break faster than crimped ones failed.

Ecomike said:

Nice write up and nice pictures. I still have my C-101 on my 87 Wagoneer!

Most, it not all my problems have been O2 sensor wiring getting to close to bad stuff, like driveshafts and Ex-manifolds, and poor sensor grounds, especially both sides of the TPS.
I had the same issue with my knock sensor, and I am getting rid of all of the grounds and using battery to starter cables. I am also cleaning the harness up by getting the slack out, so it doesn't lay on the intake or near the head, a lot of my loom had melted already. (4 gauge)

My C-101 has 278,000 known miles on it.

Mine has 293,000 on it

Last thought, PVC electricians tape is worse than duct tape under the hood, neither holds up worth a damn under the hood.

I know, im planning on rewiring the sensor grounds so its just temporary

While expensive, electricians self vulcanizing rubber electrical tape for high voltage work does work well under the hood. I also like the liquid electrical tape in a bottle.

Where can I get the self vulcanizing and ill see how it does lol

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kastein said:

I definitely would like to see this as a FAQ article

Thanks, if this gets that far ill definitely put more pics and more detailed readings after the fact, hellz yeah 4.99V at the ECU side of the TPS!

I actually prefer thermal sealant filled heatshrink butt splice crimps over soldering in an engine compartment. The thermal sealant does a darn good job and if you use a proper ratchet or hydraulic crimper (not the silly sheetmetal pliers style ones) a crimped connection is every bit as good as a soldered connection, and much harder to do wrong. Either way is ok though as long as you do a good job

Im trying to find those crimpers you were talking about, they are never in stock and i have to special order... but the butt connectors are always sold out at the autozones and advances, including walmarts in my area lol

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Home Depot is where I usually find it. It is about $5-6 / roll, and it is about 1/16" or 1/32" thick rubber tape. Looks just like electricians tape, but it is used for outdoor insulation on large 480 V and higher voltage insulation on power line connections at the entrance to the building (industrial). It stretches if pulled tight and self vulcanizes.

Really great stuff. I usually it find hiding somewhere in the electrical section.

One cool online place many of you may not be aware of is http://www.mpja.com/
for electrical supplies

Bold man... Nice write up, all I have is the CPs bypass and that's as much as I can handle.

Mike1331 said:

Bold man... Nice write up, all I have is the CPs bypass and that's as much as I can handle.

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honestly its not that bad. clip close to the connector, find the corresponding one on the other side, and temp tie them together, then when you get em all done, do you final length checks, clip away.