Let's rebuild a wiring harness.

[deabionni]

I swapped a GTE into my '86.5, and have been unable to get the new engine to start. After much troubleshooting, it looks like the ECU is not happy with the Igf signal it's getting back from the igniter. I received a (supposedly good) wiring harness from a member on here; but after much troubleshooting, we suspected the wiring harness itself was the problem.

The harness was all taped up, instead of being wrapped in a proper wiring loom. After unwrapping most of the main part of the harness, this is what we found:

Here's some more interesting parts of the harness:

...wiring by the plugs at the ECU are spiced...

...some parts are spliced/taped throughout the harness...

...and in the middle of the harness, there appears to be damage from a prior fire.

The fire damaged part is poorly taped, but the wires themselves seem to be complete (except for the missing shielding).

I have the old harness from the GE engine, and plan on creating one good harness from these two harnesses.

Old GE harness:

I have no prior experience at rebuilding engine harnesses, but I am pretty good with soldering and wiring in general. Any pointers or help in rewiring this harness is greatly appreciated.

 

[Kckazdude]

If it were me I would source anouther engine harness before I tried merging the two harnesses together. I looked at it also and found I was better off with a realy badly damaged harness and a decent harness out of a GTE car than trying to use my GE harness to repair the GTE harness.

 

[rtrdpenguin]

My harness has those bundles of spliced wires near the ECU. I don't think it's fire damage, I think it's someone swapping yellow plugs for grey plugs or vice versa. My plugs were grey for the ECU and were clearly spliced since all the engine to body harness connectors were still the yellow style plugs =\ I have bad ignition signals too, and my tach bounces up and down instead of working normally.

 

[HommerSimpson]

you see the big round plug by the dignostic box... there is another plug at other end of harness... they are the same plug and will interchange... and it will run .. but very crapy... the one by the diag box is the igniter.. the other is fuel pump thingy...

so my question is... did you have harness in car the way it should LAY>>> ? then everything pluged in ?

the blue tape and some of the black is factory....its were wires all meet..

You can ohm the wires make sure they are all good... and looking at wiring diagram is not to hard to do..and trrace wires down.. especially with it out of car... other then that it does not look that bad...

 

[cadman]

Well it really doesn't seem to look that bad from the pictures. I've seen worse. If you have some time, I would do this. One at a time, peal the tape off the wires, trim out the bad parts, and solder in a new wire section. It might be your cheapest option. Not the best... but cheapest. I know how wiring goes.

Print yourself out a good wiring diagram.

Get a tester, and just start testing connections, use a way to mark every good wire. If there's a bad wire, see if you can find the problem, or replace it.

It's going to take some time, but if you don't want to spend a lot, it might be your best bet.

 

[suprabad]

I'd bite the bullet and get a new harness.
I know it's expensive, but so are fires and shorted out electrical components, and that's before you factor in the tedious work of troubleshooting an old wiring harness. I think you're asking for a heartache.

 

[deabionni]

Believe me guys, I'd get a new harness in a second if I had the extra money. Right now, all my extra money (and then some) is tied up in this swap; and I just can't afford another harness right now. I'd get another used one off someone on here, but I don't know if I'd trust that; as the previous owner of this harness said that this was a good working harness. (So much for trusting people at their word).

Anyway, I unwrapped my old GE harness, and other than the connectors I already cut off for this new harness; my old harness looks great.

Here's the untapped section of the bum harness I was sent:

Looks like quite a bit of work ahead of me, but I should be able to take most of the old harness apart to make my new harness out of. It'll most likely be a few days worth of work, but I feel confident that I can build one good harness out of these two and save myself a few hundred dollars in the process.

I plan on photo documenting everything along the way, so if I make a mistake; hopefully someone will catch it long before I re-wrap the harness back up. Also, maybe someone else in the future might be able to use my work as a roadmap if they have to do the same work in the future.

 

[gtsfirefighter]

That's some very tedious work ahead for you and I wish you luck. I don't know if I'd have the patience for that. If you had a little extra money, one of the vendors here, can't remember which one offhand, is rebuilding harnesses.

Ken

 

[Quin]

This may be completely wrong in every way, and I don't know at all if it'd work, but you have both ECUs, so maybe you could test it.

What if you just added the GTE stuff (like the CPS) to your GE harness and used that? Might have to splice the GTE plugs onto the GE harness, but I'd rather use a harness that was 100% good with some add ons and slight modifications (assuming you can do them well, you said you were comfortable and seem confident) then try and repair a harness that is half shit right from the get go.

 

[deabionni]

What if you just added the GTE stuff (like the CPS) to your GE harness and used that? Might have to splice the GTE plugs onto the GE harness, but I'd rather use a harness that was 100% good with some add ons and slight modifications (assuming you can do them well, you said you were comfortable and seem confident) then try and repair a harness that is half shit right from the get go.

I may give that a try.

Tomorrow I'll have both harnesses laid out side by side, so I'll evaluate the best way to tackle this project. Adding the GTE plugs to the GE harness is something I may end up doing.

Either way, I'll photo document everything.

 

[shaeff]

If I were you, and I were going to splice the poop out of that harness, I would certainly stagger the splices so I don't get a giant knot-like-bump in it.

Think: Boa constrictor eats dog.

 

[omfgitsdonovan]

only thing i have to say to you is good luck tackling such a project.

 

[deabionni]

If I were you, and I were going to splice the poop out of that harness, I would certainly stagger the splices so I don't get a giant knot-like-bump in it.

Think: Boa constrictor eats dog.

I'm going to avoid splices where ever possible. I'm going to look at both harnesses very carefully, and any wires that need to be replaced on the GTE harness; I'll see if I can get the entire wire from the GE harness, to put into the GTE harness.

For instance, let's say I find a black wire with a blue strip that I need to replace in the GTE harness; and it runs from the ECU to the CSI. The first thing I'll do is check the GE harness to see if it has the same wire that runs to the same plugs. If it does, then I'll use a de-pinning tool to pull that wire + it's pin at the ECU side; and then pull that wire + it's pin at the CSI side. I'd do the same on the GTE harness, and then I'd replace that wire with the complete wire + pins from the GE harness. Result: new wire, and no splices!

If I can do that with most of the bum wiring harness, then I can replace most of the harness with good wiring; and keep splicing wires into the bum harness to a bare minimum. There are some wires which I'll have to splice on the GTE harness, as the GE harness doesn't have all of the wires + connectors that I need; so when I do splice, the splices will be staggered.

 

[HommerSimpson]

Have you asked the person you bought it from to give you a partial refund... Like 99% of it ?

So far ive bought a maft pro..&. set of pistons from people off here and both have issues i was not told about...

 

[deabionni]

^^^ LOL, naa. It was so many month ago, that I can't even remember who I got the harness from. (However, I still have his name and address). That's a funny story though.

I traded the GTE harness that came with this engine for his GTE harness; as the one that came with my engine was for a stick, and I needed a harness for an automatic. We traded our harness even up. Funny part was, I paid $18+ to ship my harness to him priority mail insured. When he received the package, he pulled my harness out of the box, replaced it with his harness; and put "moved, return to shipper" on the box.

In the end, he got a harness in better condition; and it didn't cost him a penny.

 

[ForcedTorque]

That's some very tedious work ahead for you and I wish you luck. I don't know if I'd have the patience for that. If you had a little extra money, one of the vendors here, can't remember which one offhand, is rebuilding harnesses.

Ken

That would be 935 Motorsports. The cost is cheaper than most used harnesses, but I can't remember exactly how much. It appeared to be a great deal to me.

 

[deabionni]

Finally got off work today, and will post up my progress later.

EDIT: I just checked out 935's prices, and the price to rebuild the harness is very reasonable for the amount of work involved. I still don't have that much money available, so I'm still foraging ahead as planned.

If my re-wire doesn't work, then I may be able to have someone rebuild it for me next month. Thanks for the info, guys!

 

[Quin]

Have you asked the person you bought it from to give you a partial refund... Like 99% of it ?

So far ive bought a maft pro..&. set of pistons from people off here and both have issues i was not told about...

My whole car is an issue I was not told about lol

 

[deabionni]

Here's just a quick update of how I'm fixing the melted wires. I'm starting out by replacing the wires that are melted, with wires that I have in my old GE harness.

Here's one of the melted wires out of the GTE harness:

Here's it's replacement wire out of my GE harness:

Here's the old and new wire together:

And here's the new wire sitting in the GTE harness:

Fixing the harness this way, I should be able to keep splices down to a bare minimum. Here's more of a step by step of how I'm doing this.

First, I choose a wire that needs to be replaced (an old wire by a newly replaced harness):

Then I trace that wire back to the ECU connector:

Next, I pull the wire + pin out of the connector:

Then, I trace the wire back to it's other connector; and remove the wire along with it's pin:

After removing the same wire from the GE harness, I plug the wire into the "sensor" plug first; then I route the wire towards the ECU. Fishing the wire through the rubber grommet for the firewall is the hardest part of replacing these wires.

Lastly, I plug the wire into the ECU connector, and we have a replaced wire.

Good as new!

Now just 8,527 more wires to go. :aigo:

 

[skipbarber]

time consuming to say the least, but I think if you manage to transplant all the wires successfully, you'll be golden.