Rebuilding your old wornout wire harness diy

Abe's 1987

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#1
I figured I'd actually contribute to the community and actually post a diy thread. Since my alternator wiring was all a mess I needed to fix it. The wiring got brittle and started breaking right at the connector. I just really wanted to keep the old connector and pins so I decided to rewire the connector. I pretty sure this works for any connector. Could also use steps in here to just swap out connector on good wiring. So here we go. Please do go easy on me as I'm not a professional at this and my work may look sloppy.

Tools I used:

Straight pick
90° pick
Neddle nose pliers
Soldiering gun
Solider

Parts needed:

I opped to keep the same wire color coating so all I needed to buy was wire which I got from Advance auto parts. The auto parts stores do have a nice variety of colors. Other then that nothing else is really needed. Here are the pictures of all I used just to show how simple it is.

20180328_120437.jpg 20180328_120924.jpg 20180328_121212.jpg

From there I cut the only one wire the connector was hanging by and sat on a comfy chair to start getting in the mess. If your just changing connector on good wires then dont cut wires.

20180328_110755.jpg

As you can see someone had already used those butt connector. I don't really like those as water gets in there and corrodes the wire.
Now here is what I'm left with to repair.

20180328_111556.jpg

I use the 90° pick to remove the rubber boots careful not to puncture them. If your just swaping out the connector just slide the boots down the wire and proceed to next step.

20180328_111710.jpg

Next I use the straight pick to depress the inner locks on the pins to remove them out of the connector. I did this process one pin at a time this way I didn't mix the wires in the connectors. Again if your just swapping connectors onto good wiring then snap old wire into new connector.

20180328_111825.jpg

Then I used the 90° pick to unbend the crimps on the rubber coating on the wire. I tried to unbend the crimp on the wire but it was impossible without destroying the pin so I cut the wire right at the pin.

20180328_112529.jpg

Don't worry about the extra wire still crimped to the pin as it will be out of the way. This is where the soldiering comes into play. First determine how much new wire you need to repair and cut to length. As I stated before I wanted to keep the color coating the same. Now remove enough rubber coating on the new wire to perfectly fit from the coating crimp to the end of the wire crimp on your pin. Slide the wire through the coating crimp and crimp down hard on the wire coating. Then solider the wire to the pin. Should look like this. 20180328_113538.jpg

I made sure to tug on the wire to make sure the connection was strong. Then I inserted the new fixed wire back into the connector and reinstalled the rubber boot. Repeat on the other two wires and the end product should look like this.

15222612652541746803332.jpg

More to come!!! Will show install to car harness!!!!
 
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Piratetip

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#2
Not trying to be confrontational but you should really modify the way you are performing these wiring repairs.
Soldering connections in an automotive environment is not a good method.
The joints won't hold up long term.
Short term they may be ok, but the vibration and harsh environment can make solder joints fail down the road.

Best to buy new replacement pins and a good crimper to re-assemble everything.
A good (not best) quality crimper is not very expensive and they make a world of difference.

This one has crimped hundreds of connections without issues for me. (only ~35$)
https://www.delcity.net/store/Open-Barrel,-22!12-Gauge/p_808417.h_268192
There are of course much much more expensive and fancy crimpers out there, but this one has done everything I have asked of it so far.

What type and gauge wire are you using?
At a minium I would recommend GXL cross link wire on a vehicle. (Rated to 257F melting point among other good attributes for the vehicle environment.)
A step up from that would be Tefzel
I use DelCity for a lot of supplies, they have decent prices.
https://www.delcity.net/store/Cross!Link-GXL-Wire/p_804942

Even splice connections in the vehicle I would use a crimped butt connector with a very high quality heatshrink / seal.
Use a butt connector like this style: https://www.amazon.com/3M-Heat-Shrink-Connector-Piece/dp/B008HMHJDO#customerReviews
The shrink tubing has an adhesive inside so when you put the heat gun on it the connection is totally waterproof.

Nice work on the dissassembly and re-use of all the weatherpack components though.
 
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Abe's 1987

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#3
Cut that old butt connectors out and the strip the coating at least half an inch. 15222633382161315249611.jpg

And strip half inch on the new wires.

15222635574182088890211.jpg

Now throw some heat shrink on. Make sure it is away from where your soldering so it doesn't shrink prematurely.

1522263823969705585730.jpg

Now it's time to solder your repaired harness back to the wire harness. There are many techniques on soldering most of them good so just figure out which one works best for you. I'm doing the bend exposed wires in half like a hook the hooking the two ends together and twist them. Like so

1522264255854566984625.jpg

I find this way to be a stronger connection. Here it is soldered.

15222644657661372609292.jpg

And here is it finished with the heat shrink. This helps keeps the soilder sealed from the harsh weathering

15222648325251277496342.jpg

Then repeat and end result should look like this.

1522265528890596804889.jpg

Now finish off with electrical tape and test wiring by plugging in and testing the system. And we are done.

15222658388131550162572.jpg
 

Abe's 1987

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#4
Not trying to be confrontational but you should really modify the way you are performing these wiring repairs.
Soldering connections in an automotive environment is not a good method.
The joints won't hold up long term.
Short term they may be ok, but the vibration and harsh environment can make solder joints fail down the road.

Best to buy new replacement pins and a good crimper to re-assemble everything.
A good (not best) quality crimper is not very expensive and they make a world of difference.

This one has crimped hundreds of connections without issues for me. (only ~35$)
https://www.delcity.net/store/Open-Barrel,-22!12-Gauge/p_808417.h_268192
There are of course much much more expensive and fancy crimpers out there, but this one has done everything I have asked of it so far.

What type and gauge wire are you using?
At a minium I would recommend GXL cross link wire on a vehicle. (Rated to 257F melting point among other good attributes for the vehicle environment.)
A step up from that would be Tefzel
I use DelCity for a lot of supplies, they have decent prices.
https://www.delcity.net/store/Cross!Link-GXL-Wire/p_804942

Even splice connections in the vehicle I would use a crimped butt connector with a very high quality heatshrink / seal.
Use a butt connector like this style: https://www.amazon.com/3M-Heat-Shrink-Connector-Piece/dp/B008HMHJDO#customerReviews
The shrink tubing has an adhesive inside so when you put the heat gun on it the connection is totally waterproof.

Nice work on the dissassembly and re-use of all the weatherpack components though.
Yeah this was a cheapish fix I guess. Probably would be better to use new everything.
 

Piratetip

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#5
It will for sure work :D

Did it resolve the alternator issues?

What else have you yet to tackle on your vehicle now?
 

Abe's 1987

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#6
It will for sure work :D

Did it resolve the alternator issues?

What else have you yet to tackle on your vehicle now?
Sadly she still isn't charging.
Still gots to get it charging and then got to get the fuel system right and finally the issue with the headlights. Fuel pressure drops to zero after shut off and vac isn't getting to the fpr. Other then that everything else seems to be in order.
 

Piratetip

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#7
Does your battery indicator light work in the instrument cluster Key On Engine OFF?
 

Abe's 1987

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Piratetip

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#11
Has that instrument cluster bulb ever worked?
It can't be burned out if you want the alternator to operate.
 

Abe's 1987

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#14
Yeah bulb should be good. I'm going to recheck fuses and test wires once more. I might as well drop a new bulb in as well. Well let you guys know on my other thread.
 

3p141592654

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#16
Also you can do a quick test of your new wiring.

White should read battery voltage (its the voltage sense input)
Black should read 12V with ignition on.
Grounding yellow should light the instrument Charge bulb with the ignition on.

Since your wiring seems hacked up would be good idea to check.
 

Zazzn

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#17
You can also find alot of the terminals used on the mk3 here.

http://www.cycleterminal.com/motorcycle-connectors.html

Usually, they are the MT090, TS090

I picked up the crimper from him along with the picks to unlock the connectors. Super handy. He also has the denso alternator plugs with new terminals.
 
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suprarx7nut

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#18
Agreed with Piratetip on the anti-solder stance. Soldering in the cabin is borderline, but I would avoid it in the engine bay. In addition to vibration concerns, tin and copper form an interesting (and horribly inconvenient) boundary layer that can disintegrate over time in the presence of heat. It's called Kirkendahl Voiding and I've seen it in applications around 350F. The engine bay should mostly stay below that, but the vibration may hasten the effect. It's a nasty phenomenon because the connection will look perfect. The boundary layer is what creates the problem and you can't see it until you section the interface and look at it in a SEM. In reality, it would just cause mysterious electrical gremlins for a DIY mechanic until you replace the connection.
 

plaaya69

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#20
Also Yotaconnectors.com is back online. I personally spent about $200 with them on every connector I can get my hands on. Good quality connectors and I suggest you also look into the Lamp Failure Box bypass connector assembly if you do order anything from them to avoid problems later with the tail lights going out or other issues. Just another option if you are looking around.
 

3p141592654

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#21
Don't forget that the ECU and all the other electrical "boxes" in the car are full of solder joints, as is any other electronic device including your phone, computers, etc. There is a good body of knowledge out there on how to make reliable long lasting solder joints. The igniter is an example.

A good reference is NASA-STD-8739.3. Space qualifed hardware has traditionally the highest level of reliability of any manufactured components.
 

Enraged

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#22
The home mechanic working on their Supra is not going to be doing NASA certified work.

All of the solder joints you mention are fixed positions ie circuit boards. For the ignitor, they are soldered but the wiring is appropriately braced. On a wiring harness, vibration is a major concern for solder joints. It's not even worth arguing. For the time and convenience of a quality crimp joint, why would you even bother soldering?
 

Abe's 1987

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#23
The home mechanic working on their Supra is not going to be doing NASA certified work.

All of the solder joints you mention are fixed positions ie circuit boards. For the ignitor, they are soldered but the wiring is appropriately braced. On a wiring harness, vibration is a major concern for solder joints. It's not even worth arguing. For the time and convenience of a quality crimp joint, why would you even bother soldering?
I think the argument is if a NASA solder can hold up on a space shuttle why wouldn't it work on a car. Yeah if we are talking about decades of use then yeah I would see the argument but temparay use it works.

I've heard that they sometimes preform quick solder repairs while in space just to return back.
 
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3p141592654

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#24
The claim was solder in under hood high temperatures would lead to Kirkendahl Voiding and is a no go. Well, that's not true, or your igniter would be about as reliable as a 76 Dodge Aspen. Reminds me of the purple plague warnings years ago, long since dealt with through proper process controls.

The NASA manual is a set of work instructions for best practices. Really, my daughter could follow it. Its clear and well written. And for that matter, the "home mechanic working on their Supra" won't be doing mil qualified work either such as MIL-T-7928 Mil-std-454, etc. for crimp connections. But if they are making electrical connections they should follow some best practices or they will be producing crap connections either way.

Bad crimps made with cheap tools are just as unreliable and plentiful as bad solder joints. I've seen plenty of both. And then there are the insulation displacement connectors IDC widely used by the aftermarket. Those are horrible in comparison to both solder and crimps.

Yes its true, unsupported solder joints in high vibration environment are not reliable. Its also true that unsupported crimps are not reliable in a high vibration environment. But properly supported with stiffeners they are fine. Bundled in a loom they are completely reliable. You will find butt crimps buried inside the stock wiring harness and they always are attached to a stiffener. Its critical not to nick the wire in both styles. That serves as a nucleation site for failure.

Most important is to guide and support cables and cable bundles correctly, to keep stress away from joints and connectors. Solder vs crimp is more a matter of personal taste and availability of the required decent quality crimp tools or good soldering equipment. For production jobs you will be up against certs that may force your choice, but for this kind of application both work fine.

For corrosion concerns you can use a heatshrink with internal sealer or a conformal coating like CONATHANE CE-1164 .
 
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suprarx7nut

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#25
The claim was solder in under hood high temperatures would lead to Kirkendahl Voiding and is a no go. Well, that's not true, or your igniter would be about as reliable as a 76 Dodge Aspen. Reminds me of the purple plague warnings years ago, long since dealt with through proper process controls.

The NASA manual is a set of work instructions for best practices. Really, my daughter could follow it. Its clear and well written. And for that matter, the "home mechanic working on their Supra" won't be doing mil qualified work either such as MIL-T-7928 Mil-std-454, etc. for crimp connections. But if they are making electrical connections they should follow some best practices or they will be producing crap connections either way.

Bad crimps made with cheap tools are just as unreliable and plentiful as bad solder joints. I've seen plenty of both. And then there are the insulation displacement connectors IDC widely used by the aftermarket. Those are horrible in comparison to both solder and crimps.

Yes its true, unsupported solder joints in high vibration environment are not reliable. Its also true that unsupported crimps are not reliable in a high vibration environment. But properly supported with stiffeners they are fine. Bundled in a loom they are completely reliable. You will find butt crimps buried inside the stock wiring harness and they always are attached to a stiffener. Its critical not to nick the wire in both styles. That serves as a nucleation site for failure.

Most important is to guide and support cables and cable bundles correctly, to keep stress away from joints and connectors. Solder vs crimp is more a matter of personal taste and availability of the required decent quality crimp tools or good soldering equipment. For production jobs you will be up against certs that may force your choice, but for this kind of application both work fine.

For corrosion concerns you can use a heatshrink with internal sealer or a conformal coating like CONATHANE CE-1164 .
I'd put money on it that the solder joints in the OEM engine components all use relatively uncommon solders that use very low tin formulas or are tin free. This avoids the common Kirkendahl voiding. If you use a 60/40 or otherwise common Radioshack sort of lead-free (and commonly high tin) solder, Kirkendahl voiding is a possibility.

There's also a formulation of automotive solder that handles vibrations far better than typical solders. I don't recall the blend now (Indium maybe?), but we considered it in my previous job where we had a solder joint exposed to vibrations during manufacturing.

That's interesting in the NASA standard that they refer to tin solders without mention of Kirkendahl Voids in that standard. They mention Kirkendahl voids throughout their wire bonding section, but never get into much detail other than Cu-Sn bonds can have Kirkendahl Voiding which leads to wire bond failures.

https://nepp.nasa.gov/index.cfm/20860

I still think the average home mechanic is more likely to have a successful crimp joint in an engine bay than a solder joint, but it's just a guess without data to back it up.
 

Enraged

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#26
I don't think the solder joint itself is actually the concern, it's the wire right beside the solder joint. That wire is going to experience the worst flexing, and potentially failure.

What do race teams do? If they solder, I'd say solder. But as a prime example of the most extreme automotive application, if they have decided to crimp everything, then maybe that's the best way to do it.

MotoIQ actually has a series of really good articles about wiring a race car: http://www.motoiq.com/MagazineArtic...d-Racer-Part-8--Planning-for-Performance.aspx
 

Abe's 1987

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#27
But would a crimped solution face the same issue as a solder especially in the engine bay? The heat and vibration would warp the crimp causing same issues wouldnt it? Ive seen a few times the wire came free from the factory crimps over the years of use!
 

plaaya69

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#28
I been doing a good tight crimp that is tight and strong, then I solder it, then use some dielectric grease to protect everything from the weather elements and double heatshrink it all up (unless weather tight seal is used on connector). I feel that with just a crimp once water gets inside there like with grounds or other exposed terminals, it will start to corrode and break down the wire. I know the grounds on Toyota's have been good but the Chrysler grounds I have worked on in the past were almost non existent due to corrosion.

This is overkill for my new engine harness but does anyone else do something similar?
 

Abe's 1987

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I been doing a good tight crimp that is tight and strong, then I solder it, then use some dielectric grease to protect everything from the weather elements and double heatshrink it all up (unless weather tight seal is used on connector). I feel that with just a crimp once water gets inside there like with grounds or other exposed terminals, it will start to corrode and break down the wire. I know the grounds on Toyota's have been good but the Chrysler grounds I have worked on in the past were almost non existent due to corrosion.

This is overkill for my new engine harness but does anyone else do something similar?
Sounds like a full proof plan. I might try this.
 

3p141592654

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#30
You can get mil reliability with either crimps or solder. Its about the process, and for crimps using good tools. High vibration needs strain relief. Use a stiffener to get the motion away from the transition to the connector for solder and crimp connections. Vibration will eventually kill everything, but it can be managed.