Making my own/Re-Wiring my Engine harness.

[empera]

well since i couldnt figure it out and after swapping the harness and still have not solved the issue, i've decided to pretty much make my work wiring harness to go with the AEM. I will only use the things i need. So i have a few questions for you wiring gurus and hopefully i can get the car going again.

What is the exact gauge used in our wiring harness?
Where can i buy some shielded wire to use for the CPS?
Where is the best place to buy bulk wire, in different colours maybe?

If you can help please do.
Thanks,
-emp.

 

[tlo86]

http://www.aircraftspruce.com/catalog/elpages/shieldwire.php bam suckah! very important in aircraft from what i remember but that was just 1 google search...

the gauges vary and if i remember right its 18 gauge (for most) and 16 gauge (for some, like the larger ground wire for the alternator plug is this size) for color though im not quite sure... radioshack has some different colors but the wires have large strands isntead of small strands of copper and it can be funky to route in tight places or to wire together

 

[empera]

lol i've been searching yahoo and couldnt get a good place...Thanks man!

 

[Nomad707]

good luck with the harness project.. its way better then stock when done, and if done properly.. i made a harness for a motorcycle once.. with plugs EVERYwhere.. so it was completely detachable easily.. so repairs or additions could be made with absolute ease.

 

[empera]

thanks man, im gonna need all the help i can get. Im gonna check out radioshack tomorrow and see if they carry any extra pins for the plugs and see wat else they have. Hopefully i won't hafta order anything, but we'll see...

 

[Nomad707]

OH.. i also suggest if you do this project.. make a plug near where the harness goes into the firewall.. this way you can disconnect the harness from the outside without fishing shit out... thats the ONLY thing i liked about my wifes old del sol

 

[tlo86]

OH.. i also suggest if you do this project.. make a plug near where the harness goes into the firewall.. this way you can disconnect the harness from the outside without fishing shit out... thats the ONLY thing i liked about my wifes old del sol

yeah that is a good tip, anywhere where the harness will be a PITA lol for the 7m its the exhaust side all those connections around the water pump p/s area ugh and the intake manifold area. it was nice to see the improvements from the M series to the jz series when taking the harnesses off and installing... 2jz was cake in comparison hehe

 

[jetjock]

Radio Shack? Lol...

 

[empera]

Radio Shack? Lol...

yes...i know, im sure they wont have wat im looking for but im hoping they might still have some things i will need. Plus i need to pick up some solder and heatshrink.

 

[jetjock]

What you need is to take the advice given in another thread and do signal tracing. The ECU doesn't operate off continuity you know. What you have is a simple problem that should be easy to resolve. Far easier than building a new harness.

Or perhaps you should accept you're not cut out for this kind of troubleshooting and enlist the help of any auto electric shop or competent mechanic. Either should be able to fix it in minutes.

 

[empera]

What you need is to take the advice given in another thread and do signal tracing. The ECU doesn't operate off continuity you know. What you have is a simple problem that should be easy to resolve. Far easier than building a new harness.

Or perhaps you should accept you're not cut out for this kind of troubleshooting and enlist the help of any auto electric shop or competent mechanic. Either should be able to fix it in minutes.

I think i have tried everything and i'm not sure if i would trust any mechanic with my problem, what if they are just as stumped as i am. I have had many supra guys look at this and nothing. I just dont see what else could be the problem except the harness.

 

[cruisnhard]

If you still need a harness you can get the diy kit from diyautotune. It comes with the correct size and everything is labeled. It also has shielded wire for the ign.

 

[jetjock]

The hard reality is you're stumped because you don't know what you're doing. Again, what you have is a minor problem any first year electrical student should be able to resolve using simple methods you haven't even tried. I could do it with my eyes closed. This car isn't the space shuttle you know.

And I said *competent* technician. Why would you assume he or she would be as stumped as you? As for "supra guys" you're kidding right? Don't you read this and the other forums? The plain truth is when it comes to this stuff a majority in this community couldn't troubleshoot their way out a paper bag.

Sigh. Good luck with it...

 

[ZFast300Z]

Just read the other thread on your ignition firing problem. I would recommend that before you go and build your own harness (which if you haven't before, its not as easy as it sounds) that you have someone with a scope determine if your getting a firing signal on IgnT and if the ECU is sending the proper signal voltage to the igniter for which coil to fire. You can rule out a lot of problems, and I know our shop wouldnt charge you more then .5 or 1 hour for that.

As for your question about where to buy wire, on my personal 300zx, and all the cars I have built harnesses for, I went straight to painless. They sell wire in bulk, and it is stranded wire that works great in automotive applications. It comes in a variety of colors and they also have color with tracer available. Great for being able to retrace the harness should something be wrong.
http://www.painlessperformance.com/webcatalog/catview.php?SearchField=24

 

[empera]

Listen i respect your input and i know im a novice. I understand that its probably something really simple but seeing how the harnesses for our cars are 20 years old it wouldnt be such a bad idea in rewiring it or atleast going through it. I will take your advice and get someone is Electronically Certified and knows what he is doing and i will have them take a look at the car.

Reason why im afraid is because our cars are also rare and not many have worked on them but i guess if you know the ignition/wiring system on most cars you should be able to figure out the supras.

Also the supra guys that i had take a look at the car have either done their own wiring harness and stand alone or have done extensive work on their cars. Not trying to make up excuses, i'm just getting a little stressed with the car. Maybe i need to give it a rest for a few weeks.

 

[jetjock]

Zfast: Hey, how bout that....a competent technician.

Empera: You're right. I don't know the condition of your harness but it can still be fixed. I've repaired a bunch of them. I'm also not saying you're stupid. You're simply ignorant about the proper way to do this and there is a big difference between ignorance and stupidity. What is stupid is making your life harder by refusing to seek real help, either because of ego or being cheap, when you've been bested.

 

[ZFast300Z]

Zfast: Hey, how bout that....a competent technician.

I would like to think so. UTI grad. 3 years in the field so far, as a Cadillac, Corvette, and Diesel technician for GM. I wish I would not have told my Service Manager that my specialty was electrical and driveability. The guy doing brakes in the corner of the shop always seems like he is having a way better day then I am.

Empera

Im not entirely sure where you are from but around me independent shops charge around 70-80 an hour for electrical work. Tell them that all you want them to do is scope IgnT, IgnA, IgnB (I believe those are the Supra ECU to igniter wires). You want to see a square wave 0-5 volts on IgnT. As for IgnA/IgnB (im not a supra expert here) you should see either 0/5, 5/0 or 5/5. These are the signals that tell the igniter which coil to fire. If you could get someone to scope those and get back to the guys here on SM, I'm sure we could give you a little more direction before you go attack the harness.

If your going to build a whole new harness, my advice would be to completely remove the old harness from the car and lay it out on a big sheet of plywood (similar to the way it would run in the car). Then set up a second sheet of plywood next to in and work at it one circuit at time.

 

[empera]

im gonna talk to a friend who went to UTI but i dun think he has a scope.

 

[jetjock]

Z: Hey, any monkey can do brakes. You're in the elite and I wish you'd hang out here more often. I need the rest...

I also specialize in electrical, driveability, and emissions although I don't do it for a living. I agree his problem has to lie in coil pack encoding. He must be getting IGt for the car to run but who knows if it's synced up right with A and B. I would have helped him earlier but I knew he couldn't do that kind of testing. That said a logic probe or a 10 cent LED might have provide some insight

Fwiw I build harnesses the same way, by using a layout board. Seems to be the standard method. Still a lot of work though.

 

[ZFast300Z]

Ahhh just remember UTI commonly stands for Under Trained Idiots and not everyone that comes out of that place has a clue. As a matter of a fact, 50% of the kids that I "graduated" with could not diagnose there way out of a wet paper bag with a machete.

If he still goes to UTI, he will have access to a scope. If he doesn't, most technicians I know do not purchase there own scopes and simply use the one the shop provides. I have my own OTC scope, but with you being in Philly thats not going to do you much good. And no I'm not mailing it to you, unless there is an attractive women coming in return!

On the note of building harness, JJ maybe you can help here, the kid that owned my 89 before me did a great job of destroying ever connector on my harness. Does Toyota still sell these new (I already checked for a harness by VIN and it came back NLA) or are you stuck trying to find a harness to salvage the connectors off of?

Z: Hey, any monkey can do brakes. You're in the elite and I wish you'd hang out here more often. I need the rest...

Ive been lurking on here for a while just reading and stuff and one day i noticed at the top that it said I had 0 posts and you guys delete accounts with 0 posts. Figured I better get to work!