Let's rebuild a wiring harness.

[figgie]

deabonni

let give you some insight into the Toyota harness.

Those splices in blue are OEM split points. That is of course only ONE part. That and you are actually undertaking the easier harness. The Engine harness is cake and splistic in how it was built. Splicing in that particular harness is very minimal when compared to the rats nest that is the main electrical harness (I am in the middle of "isolating" circuits"). Glad you did not cut any more wires. It is quite easy to pull the conenctors out of the plugs. Just requires a jewler screwdriver. BTW the wires that will be spliced are probably the White/black stripe wires (grounds) and anything that shares a path with sensors (those should be small though).

 

[suprabad]

Wow...good luck. You seem organized and diligent enough, I'll pray for you.

Oh, I noticed something missing from your wiring project:

 

[deabionni]

Thanks for the tips, figgie.

I figured the blue tapped sections of the harness were OEM when I opened my GE harness and found the same thing. I'm already finding a few wires that need replaced in the GTE harness that the GE harness doesn't have; so some splicing will be inevitable. That said, I'm going to try avoiding splicing the ground wires. I may have to pull a few wires at once in order for that to happen, but I think it would be the best way to do this. We'll see how that goes once I'm at that step.

 

[deabionni]

Wow...good luck. You seem organized and diligent enough, I'll pray for you.

Oh, I noticed something missing from your wiring project:

LOL, I ended up sleeping until 2PM today because of a pretty bad headache. I wonder where that headache came from?

 

[gtsfirefighter]

^^^ 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.

Sounds like a real douchebag. If it's a member on here I'd leave some seriously negative feedback and a link to this thread.

 

[cadman]

One thing I noticed, You have two very thick brown insulated wires. Those are your knock sensor wires. You need to replace those with very good insulated wiring. I'll have pictures of the wires I used to do that with. Basically, I used thinner RCA cable, double insulated. It was a crazy challenge to strip and ground, but worth it. I see that your old Knock Sensor wiring is burned as well. I seperated these 2 wires from the rest of the harness. Like I said, I'll have pictures probably Monday to show you.

 

[deabionni]

Sounds like a real douchebag. If it's a member on here I'd leave some seriously negative feedback and a link to this thread.

I remember who it was, and he is an active member on here. I'm willing to let this trade slide, as this harness didn't really cost me anything more but shipping; however, I'm very disappointed that this harness has set my swap back a good month or so from running. (Not to mention, that this Supra is my daily driver; so no Supra = no car).

Back on topic, here's a good pic of some of the wiring hacks that I'm dealing with. This is the wiring going to the CPS plug:

Also, one quick question. I have this plug on the engine harness that's by the ECU; however, once installed, there is nowhere to plug into my vehicle. I've looked under my dash numerous times, but I don't see where it should plug in.

Here's the wires that the plugs run to:

It looks as if they go to two temp sensors by the thermostat.

 

[cadman]

Um, is it the plug that goes into your glove box light? There's a little plug I remember down there that plugs into the glove box. That looks like it. Damn if only I'd had pictures. I was just re-wiring my knock sensor wiring, and had my ECU and glove box out.

 

[Quin]

Show me the face of the connector, I've got my whole shebang disassembled and can tell you tomorrow if I don't remember off the top of my head.

 

[suprabad]

If the person who sold you that harness is an active member (as you said) then he will read this thread.....
...thereby confirming his douchebagedness.

 

[Kckazdude]

Those are the A/C fan switch pugs. Your early NA chassis isnt going to have the pulg for those unless you swap the main harness out. You also will not have a working cruise conrol without swapping main harness.

 

[deabionni]

Those are the A/C fan switch pugs. Your early NA chassis isnt going to have the pulg for those unless you swap the main harness out. You also will not have a working cruise conrol without swapping main harness.

Good to know. I'm not swapping out the main harness, so I guess that plug will just hang there. (Or I can just delete it from the harness, as I already have those two wires separated from the harness).

Out of curiosity, why wouldn't the cruise work without swapping the main harness? Everything else plugs in, except for those two plugs; which seem to be temp sensor related. Is there something else that's missing which the cruise control needs?

Also, that member that I got the harness from is an active member here; and he seems to read/post in the GTE section. So if he hasn't seen this thread, then it's just a matter of time. To that member: there is no hard feelings as I'm sure there was no malicious intent when you traded harnesses with me. I'm also sure that you thought that the harness would (at the very least) work without any problems. As you can see that's not the case.

I'm also not giving out the identity of that member, as I'm sure he's a respected member here on this forum; and I'd like him stay a respected member. I just hope that in the future he makes double sure that whatever he's selling/trading is in perfect working order, as repairing broken parts is a complete waste of time to the person receiving them.

Had it not been for this harness, I'm sure I would have had my daily driver back on the road over a month ago. I can't even begin to describe how much it sucks having to walk/ride a bike/depend on friends for a ride, when you have a perfectly good car sitting in the garage.

 

[Kckazdude]

Out of curiosity, why wouldn't the cruise work without swapping the main harness? Everything else plugs in, except for those two plugs; which seem to be temp sensor related. Is there something else that's missing which the cruise control needs?

The NA CC unit only has one connection and one vacuum port to work. The GTE CC unit however has 3 connections and onve vacuum/pressure port. The extra connections control the vacuum switch and the vacuum pump so that the CC unit can maintain speed even under boost situations. All of these connections are done through the main harness and not the engine harness. You also cannot use the NA CC usait because of cable variations between the 2 units.

 

[deabionni]

Update: Here's the repaired CPS wiring in the harness:

The wiring that I pulled out of the other harness was missing a few inches of ground wire, so that was soldered in, and wrapped with heat shrink tubing.

On that note, I carefully studied the ground wires on this new harness; and there's no way I can replace them with the ground wires from the GE harness. The other cables that tie into the grounds are too different to use on the GTE harness. Some splicing of cables will be inevitable, but I'm still going to keep the splicing down to a minimum. In fact, I think I can replace the ground from a tie-in point, to another tie-in point; so the splices will be where they are when the factory spliced in some other wires. That should make it so that there are no unnecessary splices where there shouldn't be splices.

 

[deabionni]

The NA CC unit only has one connection and one vacuum port to work. The GTE CC unit however has 3 connections and onve vacuum/pressure port. The extra connections control the vacuum switch and the vacuum pump so that the CC unit can maintain speed even under boost situations. All of these connections are done through the main harness and not the engine harness. You also cannot use the NA CC usait because of cable variations between the 2 units.

Interesting. I have the N/A cruise control unit on the car, and I do have it hooked up to the throttle body. I also have the vacuum pump required to operate the cruise control unit. The only thing I didn't see, is a place to plug the pump into; which would explain why, as I didn't switch out the main harness.

Since I have the N/A cruse control hooked up to the throttle body, if I wired the pump on a relay to come on withe the ignition, would the cruise control work then?

 

[Quin]

Couldn't you make a custom cable and use a check valve to keep boost from getting in? I can't think of a time when you'd be boosting with CC, but I don't use the resume/accel button and can't in mine (no CC).

 

[deabionni]

No need for a custom cable, as it bolted right up to the GTE throttle body I'm using. I just need to figure out a way to keep vacuum to it, and I'm thinking hard wiring the pump to the ignition with a relay just may work.

 

[Kckazdude]

Boost could get excessive enough that it would overcome the check valve. That is why there is a valve and vacuum pump on the GTE unit. Interesting about the cable hook-up. It wouldnt work on the turbo to NA conversion I did. Owner didnt care for cruise so I didnt investigate it further. I discovered the connection issues when I went to install my GTE unit. Just now getting my main harness reassembled now after going through 3 different harness to build one good harness. It is a PITA having an early production car doing a conversion.

 

[deabionni]

I'm seeing that the '86.5 isn't the best year to put a turbo into, but it's really not that bad. Just a few hiccups along the way. The GTE/Auto bracket that I'm using on the throttle body had no problem accepting the cable from the stock cruise unit. I must have gotten lucky, but I didn't see a problem with the cable when I hooked it up.

Now just to figure out that pump and vacuum.....

 

[Kckazdude]

I swapped the main harness becuase I got cool new features as well. Supermonitor harness was a bonus as well as PnP CC unit and front aux fan.