ckuske Posted August 24, 2022 Share Posted August 24, 2022 Hi All, I ran the KOEO test on my truck the other day and even though I got the TPS replaced a few years ago I got code 53 (TPS Voltage too high). I backprobed the TPS connector and noticed that the VREF and Signal Return wires were both reading 5 volts. Given the trouble code and the reading VREF and SigRet with my DVM, this makes sense. With the throttle closed, it seems SigRet is supposed to be around 1V. So, I started poking around the wiring harness. If I spread the wires to the TPS apart where they branch off the harness, the voltage on the SigRet wire would go away. So, seems like the VREF and SigRet wires are touching somewhere. This is a long way of saying what I've done to test things, and I'm looking for how I should proceed from here after you all look at the pictures of the harness. It is a mess (not my doing), and even though its obvious that it NEEDS to be fixed, how would you all go about it? The covering of the bundle is very brittle and I need to use a X-acto knife to shave it away. I am nervous about taking this apart too much as I'm nervous that I'll graze or nick something and make things work. I have known about this area being questionable but I figured if it worked before and I didn't touch it (aside from moving the harness around gently during other repairs), it would be ok(?). Well, it's clear that the current situation at this point in the harness is untenable. How should I attack this repair? Thanks! Pics below. And yes, I think it's just not the TPS wires that are in trouble here. It also looks like the sensor that gets coolant temp is just as bad or worse (see green/red wire) Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 24, 2022 Share Posted August 24, 2022 Chris - I think you've found at least some of the problems, and they must be repaired. I had to do some of this on Big Blue, and what I did was to remove the covering on the questionable sections of harness, cut the wire out ahead of and behind the problem, and graft a new wire in using solder and heat shrink. Then I put the harness back together using harness tape and convolute. But doing that is greatly facilitated by having the harness out of the truck. I did in some cases and didn't in others, and the look of the results varied. But in all cases it worked. As for removing the covering, I've used a box knife and turned the blade so the sharp side was away from the harness and used the point to split the covering. And I got lucky and don't seem to have hurt the wires. But it is tedious! And nerve wracking! Good luck! Link to comment Share on other sites More sharing options...
85lebaront2 Posted August 24, 2022 Share Posted August 24, 2022 Having done a lot of rewiring/repairing between Darth and my project car I will tell you how I would do it. If you have a large enough space to lay the harness out (I used a picnic table) that is the easiest way. Once it is laid out, take each branch and put some zip ties around each leg of the branch as close to the branch as possible. After this is done, start removing the petrified tape, it may simply unwrap or may need to be cut. Anywhere there is a splice, you will probably find a glob of sticky goo that was then taped over. Unless you have a high resistance or cross connection, I would simply re-tape them. Where you find bad areas, if the end connector can be easily disassembled and the pins (male or female) aren't too big, a piece of heat shrink can be slid over the bad section, if not, then the section of wire will need to be carefully wrapped with tape. I have found that friction tape is better than the Vinyl tape where the harness may move. The loom split covering can be found on Amazon in various colors. FWIW, here is a picture of the underhood harness for my 1985 Chrysler Lebaron convertible I was building from a 1987 LeBaron sedan: Link to comment Share on other sites More sharing options...
ckuske Posted August 25, 2022 Author Share Posted August 25, 2022 Having done a lot of rewiring/repairing between Darth and my project car I will tell you how I would do it. If you have a large enough space to lay the harness out (I used a picnic table) that is the easiest way. Once it is laid out, take each branch and put some zip ties around each leg of the branch as close to the branch as possible. After this is done, start removing the petrified tape, it may simply unwrap or may need to be cut. Anywhere there is a splice, you will probably find a glob of sticky goo that was then taped over. Unless you have a high resistance or cross connection, I would simply re-tape them. Where you find bad areas, if the end connector can be easily disassembled and the pins (male or female) aren't too big, a piece of heat shrink can be slid over the bad section, if not, then the section of wire will need to be carefully wrapped with tape. I have found that friction tape is better than the Vinyl tape where the harness may move. The loom split covering can be found on Amazon in various colors. FWIW, here is a picture of the underhood harness for my 1985 Chrysler Lebaron convertible I was building from a 1987 LeBaron sedan: Thanks for the feedback, Bill. I have the trouble area stripped of the petrified (I like that) wrap. All the wires are chafed in the same area. I assume vibration has done this over the last 40-ish years... I really don't want to try and take the whole harness out of the truck at this point - I have it almost put together. If I have to, I have to, but fingers crossed. There is enough room for me to splice in new wire and re-wrap that area. I like the friction tape idea, this stuff seems to come well-recommended: https://a.co/d/gRW7aJE FWIW, the rest of the harness looks ok. It makes sense that this would be the area that would fail as there wasn't strain relief and is right next to the passenger side of the engine block. Here are some better picture areas after removing the cover. Shorts galore! And not in a good summer way. Â Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 25, 2022 Share Posted August 25, 2022 Thanks for the feedback, Bill. I have the trouble area stripped of the petrified (I like that) wrap. All the wires are chafed in the same area. I assume vibration has done this over the last 40-ish years... I really don't want to try and take the whole harness out of the truck at this point - I have it almost put together. If I have to, I have to, but fingers crossed. There is enough room for me to splice in new wire and re-wrap that area. I like the friction tape idea, this stuff seems to come well-recommended: https://a.co/d/gRW7aJE FWIW, the rest of the harness looks ok. It makes sense that this would be the area that would fail as there wasn't strain relief and is right next to the passenger side of the engine block. Here are some better picture areas after removing the cover. Shorts galore! And not in a good summer way. It can be done in the truck, and in your case that's what I'd do. But you have to cut the wire back several inches past the bad spot in order to find good wire. And you'll still probably have to sand and/or scrape the wire to get it clean enough to solder. Plus, I use flux in addition to flux-cored solder. Link to comment Share on other sites More sharing options...
ckuske Posted August 25, 2022 Author Share Posted August 25, 2022 It can be done in the truck, and in your case that's what I'd do. But you have to cut the wire back several inches past the bad spot in order to find good wire. And you'll still probably have to sand and/or scrape the wire to get it clean enough to solder. Plus, I use flux in addition to flux-cored solder. That seems to be the right way to do it. It's been a hot minute since I've soldered, I'll have to practice before being hunched over in the engine compartment. Soldering iron, or gun? Link to comment Share on other sites More sharing options...
mat in tn Posted August 25, 2022 Share Posted August 25, 2022 That seems to be the right way to do it. It's been a hot minute since I've soldered, I'll have to practice before being hunched over in the engine compartment. Soldering iron, or gun? gun Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 25, 2022 Share Posted August 25, 2022 That seems to be the right way to do it. It's been a hot minute since I've soldered, I'll have to practice before being hunched over in the engine compartment. Soldering iron, or gun? That depends on what you have. I have both a gun and a soldering station, which is a soldering pen attached to a heat-control module. It is far better than the gun in that it keeps the heat right where you set it and is always ready. So for one or two joints I might go with the gun, but for anything more it is the soldering station every time. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted August 25, 2022 Share Posted August 25, 2022 if the end connector can be easily disassembled and the pins (male or female) aren't too big, a piece of heat shrink can be slid over the bad section The guy who will invent a kind of "split" shrinkable sleeve that can be installed anywhere along a damaged wire will be rich. Any idea my friends? Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 25, 2022 Share Posted August 25, 2022 if the end connector can be easily disassembled and the pins (male or female) aren't too big, a piece of heat shrink can be slid over the bad section The guy who will invent a kind of "split" shrinkable sleeve that can be installed anywhere along a damaged wire will be rich. Any idea my friends? No, I don't know how to do that. However, in this case Chris is going to have to cut out bad sections of wiring and that means he can slip heatshrink tubing over the piece then. But if there is just one wire that the insulation has come off of and it looks like it is good elsewhere then perhaps liquid electrical tape would work? Link to comment Share on other sites More sharing options...
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