RDAN1 Posted February 24, 2012 Share Posted February 24, 2012 I pulled the injector harness from my 88 4.0 today to clean it up and also to clean out connector 101 (wow!). At the end of the harness, wrapped in foil is a bare wire as per the picture. It doesn't connect to anything as far as I can tell. Should I just tape it in place against the foil wrapping and move on or? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 24, 2012 Share Posted February 24, 2012 Boy, I wish I still had my parts Jeep around as I'd open up the harness. IIRC, the only sensor that used a shielded type wire was the O2 sensor. While you're in there check the crimps on the sensor ground wires. Should be a clump of three in the harness heading towards the C101, goes to one wire into the C101. Going out of the C101 that wires goes to another clump of three near the MAP. If you can bypass the C101 and tie both clumps of three together and solder it would be better. This might help ya. Find your Intake Air Temp sensor. It's the sensor just to the rear of the throttle body, has 2 wires, and screws into the intake manifold. Where it's connector plugs into the harness you will see that one of the wires on the harness side is brown with a white stripe. Follow the brown with white strip wire back into the harness. You'll have to open up the split-loom plastic sheathing to follow it. It will come to a splice with 2 other brown with white wires. They're from the TPS and the CTS. The 3 wires will be spliced to a single wire headed toward the C101 connector if you have an 87 or 88. If you have an 89 or 90, you do not have the C101 bulkhead connector. Now go to the MAP sensor. Follow the brown with white wire into the harness from there. You will find a splice with 2 more brown with white wires. At the splice you will find the 3 wires connected to a single brown with white wire going toward the C101, or just along the firewall towards the engine if you have an 89 or 90. Along with the MAP sensor that you traced, they are the ECU sensor ground port and the diagnostic connector on the passenger inner fender. You now have 2 sets of 3 brown with white wires, one near the firewall and one near the engine. Cut the splices out of each set of wires eliminating not only the crappy factory splices, but also the single wire between them. Bring both sets of 3 wires together. Solder the 2 sets of wires together and insulate them properly with tape or shrink tubing. Zip-tie up your new sensor loom to allow for engine movement. I prefer to cover it with some new split-loom or wrap it neatly with electrical tape when done. Revised 12-02-2011 Link to comment Share on other sites More sharing options...
RDAN1 Posted February 24, 2012 Author Share Posted February 24, 2012 Boy, I wish I still had my parts Jeep around as I'd open up the harness. IIRC, the only sensor that used a shielded type wire was the O2 sensor. While you're in there check the crimps on the sensor ground wires. Should be a clump of three in the harness heading towards the C101, goes to one wire into the C101. Going out of the C101 that wires goes to another clump of three near the MAP. If you can bypass the C101 and tie both clumps of three together and solder it would be better. Thanks for the info. The bare wire shown is foil wrapped with the 2 wires going to the knock sensor (yellow with black stripe & purple ? with white stripe). When I pulled off the old loom, the bare wire was just open on the end like it's shown in the photo. I can trace all three wires back in the harness but they don't appear to go to the 101 connector. I'll double check that tomorrow but it looks like they go into connector 116 ??? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 25, 2012 Share Posted February 25, 2012 The ones that go through the C101 are sensor grounds for CTS, TPS, IAT, MAP, and ECU. Brown with white stripe. Link to comment Share on other sites More sharing options...
Eagle Posted February 25, 2012 Share Posted February 25, 2012 Find your CPS connector and follow the harness from the connector upstream. If it remains a single harness -- all by itself -- directly to the firewall, most likely your truck was upgraded. There was a TSB a number of years ago about the CPS harness being too long and the signal degrading between the sensor and the ECU (which is under the dashboard in the Renix trucks. The fix was a replacement harness that went straight from the CPS connector through the firewall into the ECU. Link to comment Share on other sites More sharing options...
RDAN1 Posted February 25, 2012 Author Share Posted February 25, 2012 Find your CPS connector and follow the harness from the connector upstream. If it remains a single harness -- all by itself -- directly to the firewall, most likely your truck was upgraded. There was a TSB a number of years ago about the CPS harness being too long and the signal degrading between the sensor and the ECU (which is under the dashboard in the Renix trucks. The fix was a replacement harness that went straight from the CPS connector through the firewall into the ECU. OK I traced it back from the cps and the white with black stripe goes to 101 and the purple with white stripe goes to 116. ? I also found the splices cruiser54 mentioned and can deal with those splices before I reassemble . So back to the original question : Can I just tape the bare wire back against the foil tape and move on? also since I have a manual, can I terminate and seal the wires going to the tps auto trans connector 259?..doing away with that connector would clean up the harness some..?? Link to comment Share on other sites More sharing options...
cruiser54 Posted February 26, 2012 Share Posted February 26, 2012 I'm not sure what that wire in foil does except maybe shield from RF signals? See no reason you canit do something with the TPS wires to the tCU. If it were me, I would make your harness so the sensor ground circuit no longer passes through the C101. Link to comment Share on other sites More sharing options...
tugalo Posted February 26, 2012 Share Posted February 26, 2012 The knock sensor has foil shielding to prevent spurious signals from reaching the computer. If your truck doesn't have a knock sensor, maybe the factory was using up supplies of prior year harnesses when it was built. If the foil does in fact go to the knock sensor, you can just ground it as a "shield drain" and not worry about it. Link to comment Share on other sites More sharing options...
fiatslug87 Posted February 26, 2012 Share Posted February 26, 2012 All three of my RENIX MJs have this wire to nowhere. Maybe the '88 electrical manual has some info. http://comancheclub.com/forums/viewtopic.php?f=9&t=12734&hilit=Electrical+manual Link to comment Share on other sites More sharing options...
RDAN1 Posted February 26, 2012 Author Share Posted February 26, 2012 The knock sensor has foil shielding to prevent spurious signals from reaching the computer. If your truck doesn't have a knock sensor, maybe the factory was using up supplies of prior year harnesses when it was built. If the foil does in fact go to the knock sensor, you can just ground it as a "shield drain" and not worry about it. I do have a knock sensor so I just taped the loose bare wire back against the foil insulation. While I had it open, I also cut out/removed and sealed up the ends of the 3 wires going to the transmission tps plug since I have a manual and it's not used/needed. Thanks to everyone for their input. Link to comment Share on other sites More sharing options...
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