2002 Wiring Harness Fix

Any chance of finding a replacement harness in a salvage yard?

-Chap

 

It would be much easier to splice the wires back together than replacing harness because the harness likely goes through the bulkhead.

 

Whatever you do Slim, don't use butt connectors for this b/c:
1) The connections get loose and deteriorate over time
2) It will make a huge bulge at that point

I would take the time to solder each wire and place heat shrink over the connections. It will be time consuming but if you want a good, long lasting fix, this is what you will need to do.

Like Bob Wilson always says, if you're looking to cut corners, the following rule applies:

Good, fast, cheap: Pick 2

You can use butt connectors and that will work but the 2 you will pick is fast and cheap.

 

Its hard to say if that's your problem. If there are 20 wires that go through that cable, its impossible to know what signal they would provide to what ECU that would energize blank relay etc. It is obviously a problem and the easiest place to start.

If you don't have much experience soldering, remember, flux is your best friend. Also, soldering 20+ fine wires is tedious and time consuming. Be patient, pay close attention to colors and stripes on the insulation. There will likely be orange, orange with dots, orange w/ stripes etc. Good luck, I'm not envious of your situation.

 

I would DIY b/c as much work as you do on cars, the more skills you have, the more money in your pocket. I think you may be hard pressed to find someone to take this on. Soldering is not hard and by the time you finish, you will be an expert.

 

Whoa there Francis! Be careful about going on the advice of random Internet strangers... including myself. Do your homework!

This is a false claim. Nearly EVERY car on the road today uses crimped connectors from nose to tail. Hundreds, if not thousands, in each car. So why aren't these cars dropping like files, usnavystgc?

From what I've learned, a properly crimped connector is much more tolerant of vibration than a solder joint. And there's lots of vibration in a car, especially inside the engine compartment. Solder can and will crack if subject to enough vibration -- it's not bonded to the wire like a weld, it's just molten into the cracks between strands.

Yes, your spliced loom is going to look like a snake that tried to swallow a car tire, but it's a solid fix if done properly.

Practice crimping some speaker wire or something else before diving into this loom if you're not already a pro. Make sure to strip the proper amount of insulation from each wire, and use quality connectors that crimp at both the wire and the insulation (thus relieving the wire from mechanical stress). And find something with which to cover the splice, either a junction box or some sort of wrap or loom. Electrical tape is fine.

Good luck!

 

Good advice above.

I have to design electrical systems for military aircraft, so a couple of extra points and recommendations:

1) Aircraft wiring has completely converted over to crimp connections and repairs where possible quite some time ago. Solder is only used when crimping is precluded for some reason. (The major reason is replacing an old style solder cup connector that does not have a crimp version.) USE THE CORRECT TOOL FOR CRIMPING AND THE CORRECT CRIMP FOR THE WIRE GAUGE. This is the difference between perfection and disaster. There is NO middle ground. I did not write in capitals to yell, but to make sure that critical extra attention was provided to make sure you don't waste your valuable time making the one unrecoverable error.
2) Use heat shink tubing for covering and protecting each splice. A little planning is needed. Put the unshrunk tubing on the wire before splicing. Make the length of the heat shrink quite long to provide a good mechanical grip on each wire and provide great stress relief. At least an inch on each side of the splice is recommended.
3) Use one big heat shrink tube for the whole assembly. Even more planning needed.

 

Use the internet to get educated. Type in automotive butt splice wiring, AWG sizing, etc. Depending on budget, time, etc. you will quickly get a feel for what you need or want to do. The following quick link may help give an idea of the high end approach.


How to Splice Automotive Wires | The Family Handyman


However, I'm pretty sure you want to keep it cheap, simple and effective. So:

1) Figure out the AWG first. Looking for tools and splices without knowing this is a waste of time. Find some AWG 22 through 16 and check it against what you have. Someone you know has unused scrap (but marked) wire somewhere.

2) Find your butt splices next. Recommend using uninsulated and "gapless" splices. The insulation is to prevent shocks from exposed metal, not protect the splice from the elements. Given the number of wires to splice, you don't want lots of needless space used by insulation covered by heat shrink.

3) Plan on heat shrink. In automobiles, water runs along every wire till it finds the splice. Heat shink is you best friend here. You also have limited space.

4) The last thing is to select the tools depending on present and future use. High end does not need to be more than $30. Low end does not need to be more than $10. Also keep in mind how restricted the area is. Buying a big nice crimp tool that you cannot fit into the small area being worked......I think I have mentioned the word plan too often (or too little) already. You will need both a wire stripping tool and a crimper. I avoid home depot and use the internet for real tools.


Wrench Tips #22 - Clean Splices


At the end of the splice you want to look like the small middle photo of the black covered splice.

 

Now that all the demands of the splice option have been covered in more detail, routing a replacement harness might not seem to be as much extra work as it seemed at first?

Whichever option you choose, if you haven't yet fixed yourself up with the wiring diagram manual (either on paper from helminc.com or downloaded from techinfo.toyota.com) that could be included in your preparation steps. It will show you the routing of the harnesses, where all the connections are, and all of the wire color codes so you'll know when you need to sort out an orange from an orange-dotted, etc. It will also help with your troubleshooting later because you'll know which things not working suggest trouble with which wires.

Even if you decide not to replace the harness, you should probably figure out how it comes out of the car. If it goes through the bulkhead, the way that often works (I haven't looked it up for this case) is that it's fed through the hole by one end and then a big rubber grommet, located in the right place on the harness, closes the hole. The trick is that the hole is made big enough to feed that end of the harness through, with all its connectors, up to where the grommet is. Depending on which end of the harness feeds through, if you ever had a reason to do so down the road, a big blob of splices might get in the way.

Sometimes there's a big multiconductor connector at the bulkhead instead of a hole and grommet, which would simplify things.

-Chap

 

Maybe, but that will bring few advantages and a lot of potential pains. The big advantage is swapping pins on the connector if you make a wiring mistake. The disadvantage is that it may create more problems than solve. For example, you will have to split open the harness on each side for many inches, exposing a lot of wiring to the elements and abuse. The space taken up will be huge. The connector corrosion could be significant since the wires will be somewhat exposed at the connector pins. A lot of the normal slack will be lost. The cost would be more, etc.

 

I agree that "proper" crimping is a good, viable fix but proper crimping takes skill and the "right" tools. Crimping all 20+ connectors will make a huge bulge. If it were me, I would do the soldering.

Yes, soldering is tedious, yes, cold solder joints can crack (that's why you use flux). The bottom line is that there are pros and cons to both. To me, the soldering pros outweigh the cons.

The bottom line here is that everyone will have a different opinion and some are quick to discount the first poster with an opinion so they can show how much they know.

 

I don't know why cars aren't dropping like files but the reason they're not dropping like flies is because the crimped connections are done at the factory (probably by robots by people with a factory setup that crimp everyday). I'm pretty sure Slim is not a robot and he freely admits he doesn't crimp everyday.

There is no way one can duplicate the factory connections. You can't present the best case scenario and assume all crimped connections are of that quality. The bottom line is, I'm trying to help Slim the best I know how. He posted, I gave the best advice I could.

 

From what I understand, you will be able to download it and print it.