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Advice on Sensor Wiring Harness/Splices

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ckuske

Advice on Sensor Wiring Harness/Splices

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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)

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Advice on Sensor Wiring Harness/Splices

Administrator

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!

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

85lebaront2

Re: Advice on Sensor Wiring Harness/Splices

Administrator

In reply to this post by ckuske

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:

Bill AKA "LOBO" Profile

"Getting old is inevitable, growing up is optional" Darth Vader 1986 F350 460 converted to MAF/SEFI, E4OD 12X3 1/2 rear brakes, traction loc 3:55 gear, 160 amp 3G alternator Wife's 2011 Flex Limited Daily Driver 2009 Flex Limited with factory tow package Project car 1986 Chrysler LeBaron convertible 2.2L Turbo II, modified A413

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

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.

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Advice on Sensor Wiring Harness/Splices

Administrator

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.

Gary, AKA "Gary fellow": Profile

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

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?

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

mat in tn

Re: Advice on Sensor Wiring Harness/Splices

gun

Gary Lewis

Re: Advice on Sensor Wiring Harness/Splices

Administrator

In reply to this post by ckuske

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.

Gary, AKA "Gary fellow": Profile

BigBrother-84

Re: Advice on Sensor Wiring Harness/Splices

In reply to this post by 85lebaront2

85lebaront2 wrote

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?

Jeff / 1984 F350 Crew Cab 4x4/5.8L w351 4V/ T18/ D50 4.10 front/ 8' bed.
Restored 2019-2022.
Nicknamed «Big Brother 1984», due to its soooo-looong shape & nod to George Orwell's 1984 famous novel.

Gary Lewis

Re: Advice on Sensor Wiring Harness/Splices

Administrator

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?

Gary, AKA "Gary fellow": Profile

ArdWrknTrk

Re: Advice on Sensor Wiring Harness/Splices

Administrator

In reply to this post by BigBrother-84

I sometimes use the self fusing silicone tape.
You need to keep tension and it may have trouble sticking to an oil soaked harness but it become monolithic.
It's also great for creating strain relief 'tails'

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

85lebaront2

Re: Advice on Sensor Wiring Harness/Splices

Administrator

In reply to this post by ckuske

That does look like an excellent friction tape. I usually get mine (when they have it) from the Ace Hardware here.

I see in one of your pictures a factory splice on what looks to be black wires. Those usually are fine, they seem to be spot welded together. I don't know what Ford was using for insulation on their wiring in the mid 1980s, but I have seen a lot of them where the insulation was just crumbling and falling off the wires.

The liquid insulation might be an excellent solution, I have never used it, but I have lots of salvaged lengths of various color and size wire in neat little rolls so I can most times match the OEM color and size.

Good luck with the repairs.

Bill AKA "LOBO" Profile

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

Thanks, gathering equipment, wiring, and fortitude. Not necessarily in that order.

The existing wire looks to be either 16 or 18 gauge. It looks more like 18. Would either work well, or does anyone have experience here?

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Advice on Sensor Wiring Harness/Splices

Administrator

I think it is 18, but 16 will work. If in doubt cut into one of yours and compare to a known size.

Gary, AKA "Gary fellow": Profile

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

Yep, will do! Just wanted to check with you all, I'm trying to order stuff before I cut into anything.

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

I've started to splice the good wire onto the connectors, it's 18 gauge and my soldering seems to be going well. Checking the continuity with my DVM as I go.

I ran into this connector - its clear the retaining clip has been snapped off more than once, and the wires are damaged going into the connector. I'd like to replace it.

From the connectors catalog on this site, it looks like WPT-597 but its hard to be sure, especially since Googling that part number indicates it wasn't used until 1992 for interior???

This connector is next to the carb - I think for the bowl vent solenoid? I haven' been able to find the connector number in the EVTM or Parts Catalog, I have probably missed it. In the EVTM I'm pretty sure it is C788.

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

Gary Lewis

Re: Advice on Sensor Wiring Harness/Splices

Administrator

I wish I could help, but I don't think I have any harnii that have that connector. And it sure is hard to tell from that catalog.

Gary, AKA "Gary fellow": Profile

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

This post was updated on .

Appreciate it! I snipped the zip tie that was holding the wiring to the part so I could get a look at the engineering number. E4AE-9C915-CA (Vapor Canister Purge Valve)

Now maybe I can figure out the part number for the male connector now that I have this knowledge...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

ckuske

Re: Advice on Sensor Wiring Harness/Splices

Administrator

Well no leads really... I found a WPT-597 on eBay for $15. (Much cheaper than on Amazon, FYI). It sure looks like it. I guess I have spent more on things that haven't worked.

If I get really desperate I suppose I can just put blade connectors on the wires and seal the connection somehow but that's not really how I intend to do things...

Chris

'84 F-150 XL 2WD Flareside, 302 w/ AOD transmission, Motorcraft 2150 feedback carb w/ CA Emissions, EEC-IV w/TFI, factory A/C, speed control - Info about me and my truck - My project thread

85lebaront2

Re: Advice on Sensor Wiring Harness/Splices

Administrator

I have a number of large plastic jars full of various connector shells that I have salvaged and lots of wiring same way. I can probably look over the weekend, but, I will be loading up Friday to do a Pick-n-Pull run on Saturday, so it will be Sunday or Monday before I can get too them.

Bill AKA "LOBO" Profile