Using 89 wiring harness and ECU in a pre 89

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#1
Well were finished with most of the mechanical on the shop supra at my brothers shop and now im going to start working on the electrical and harness to try to get it running this week.

Were using a 89 harness and ECU in a 86.5 chassis. We only need the basics to get the car running as its not a daily driver.

I see that 2 of the dash plugs on the wiring harnes plug into the dash harness just fine, Don't know if it will work though. If not I'll go from there and just hard wire in the essentials. Whats the other plug for?

I know this harness was out of a ABS car and the chassis its going into is non ABS, don't know if it matters though.





 
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#3
I read somewhere the plugs all plug in but the wire locations are different. Either way we will use this harness, If I have to ill just get both the harness wiring diagrams and splice or repin every plug.
 

hvyman

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#4
Kinda depends. Buddy has early 89 plugs are gray tho and the yellow harness plugged in but the headlights were always on. Has to be yellow with yellow and the right year gray with gray.

I did a 90 harness for a 87 car. It works perfect. Pretty lengthy tho. Basically the big plug i think b1 or b2 goes in the same spots i think. You cant depin and repin cause the pins are different unless you get a early 89 harness and it happens to have the same pins.

You can delete the hac sensor plug. Hac sensor is internal on 89+ ecus.

For abs you will just have extra wires. Wont matter.

If you look at the stickeys in the 1j/2j section there is the plug diagrams telling you what pin, what color, what plug, and what it is for.

Double check that you got the right wire in the right place as they are not all the same colors and there are some that might not get used.

Thats all off the op of my head.

Who did the manifold?
 
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#5
My brother did the manifold, Just gave it to a friend to get polished as well, It should look sweet once its polished. Ill double check over the wiring and see if we'll be alright on it.

Thanks
 
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#6
Oh just thought I would make it clear if not before,

The engine harness and ECU are from a 89 Turbo 5 speed ABS Car

What its going into is a 86.5 non turbo 5 speed non ABS car

So the engine harness is the gray plugs, the dash harness are the yellow plugs.
 

shaeff

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#7
Not worth it, in my opinion. You'll save so much time and frustration by just getting a proper 87-88 turbo harness/ECU.
 

Insidious Surmiser

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#9
I've done it before, but I had to remove all of the pins and move 90% of them around (some were un-used) I used to have a pin-out for this, but it was completely wrong.... I ended up just looking up what the wire color codes meant and simply matching them up... you'll need to find specific wire codes for 86.5 and 89 (obviously) just takes a bit of common sense... good luck!
 

shaeff

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#10
If finding a new harness/ECU isn't an option, then do what 89jdm7m said and de-pin the connectors, re-pin in proper orientation. You'll need the TEWD for each year setup you're working with.
 
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#11
Yeah thats no problem, My brother does this every day, Doing SR, RB, and LSx swaps into 240's. Its no problem for the electrical. Where can I get the wiring diagrams for the 86.5 and 89.. Isn't the cygnusx1 TSRM 88?
 
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#12
So it seems that there are only two dash plugs on the 86.5.. My 88 has a total of 3 plugs.. The large square one, a smaller rectangular one and a larger rectangular one..

But the 86.5 we are doing the GTE swap into only has two.. Is there any information on swapping a GTE into a 86.5?

 

oldmansupra

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#13
I did it, the harness was a JDM 88 7mgte and the shell was a 86.5. I had to convert the 3 plugs you're looking at and extend the harness about a foot. I used the TEWD for each year and figured out what each of the wires on those connectors went to. There were only a few differences, so I sourced male connectors that fit and put the pins where they should be. I had a few wires left unused, a few swapped but most just lined up. The only way to be 100% sure of what you're doing it to order in a few TEWDs, and get a multimeter to double check where the wires go. Also your tach is not going to work after you swap in the engine. Go buy the full gauge cluster out of a 87+ car from a junkyard and plug it in, it fixed it for me. I've also heard of a resistor swap you can do, by swaping out resistors in the tach. I tried this but the copper coil inside my tach fell apart while I pulled it out so I just bought a turbo cluster.
 
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#14
I have done the resistor swap on 3 tach's now.. All are fine :) If it didn't plug right in you don't have a 88 harness.. The 87 turbo and 88 Turbo harnesses plug right into the 86.5 cars.. You must have had a 89+
 

oldmansupra

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#15
Nice, yeah I messed up my tach haha but my new gauge cluster is nicer anyways :) No man I had a pre 89 for sure it had yellow plugs, external hac and other things... it was a JDM though that's the difference. JDM harnesses have different dash plugs, not that this has anything to do with your swap. Like the other guy said though if your car doesn't have ABS, then don't worry about the ABS plugs. Also you're using a manual harness so that simplifies it a lot, you shouldn't have to rewire the neutral start switch or the the reverse lights.