3.4 Swaps The 3.4 V6 Toyota engine

Wiring harness differences between man and auto

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Old Apr 12, 2010 | 11:03 AM
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Wiring harness differences between man and auto

Hey guys i have sourced an engine for my 3.4 swap and the seller does not know if the engine came from an automatic or manual T-100. He bought the engine for himself as a replacement for his T-100 and ended up not needing it. He never specified to the seller if his T-100 was an auto or not.
The engine harness is still attached to the engine and if i am correct if i could figure out if the harness was an auto or a manual it would determine if the truck it came out of was an auto or man.

The engine is a 1997 and it is out of a T-100

What are the physical differences between a auto and manual wiring harness? How can i tell what type is attached to the engine?

Is there any way you can tell if the engine would accept a pilot bearing by looking at it?
(by the way these are the pictures the seller provided he said he can get more pictures if needed)

Thanks guys


here are some pictures
Untitled.jpg?t=1271098684
Untitled-1.jpg?t=1271098862
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Old Apr 12, 2010 | 11:14 AM
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why dont you try taking pictures of something useful.. like... the harness plugs?
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Old Apr 12, 2010 | 11:22 AM
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that is all the pictures i have right now im waiting on the seller to send me some more pictures
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Old Apr 12, 2010 | 12:47 PM
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Well I can tell you since its a 97, if the plugs have 2 rows of pins then its manual, 3 and its auto.
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Old Apr 12, 2010 | 06:07 PM
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yes, after 97 they all went to the same style plug I believe. Manual should have flatter type plugs and auto more cube looking plugs. My auto plugs were white, and I think that I have read that manual plugs are gray. someone hopefully can confirm or point this out as wrong.

Doesnt he have the ECM? It will say right on there if auto or manual and 2x4 or 4x4?

Stole this shot from another thread but this is your average ECM. Everything you need to know should be here.

Last edited by dntsdad; Apr 12, 2010 at 06:15 PM.
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Old Apr 12, 2010 | 07:28 PM
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ya mine are white, except plug d is gray. Its gray because its the same plug used on the 3.0 harness and computer. but you are right in the auto's are bigger and more square than the manuals.
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Old Apr 13, 2010 | 03:06 AM
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By looking at pic.#1, it appears as though there is no problem with using a pilot bearing.
By looking at pic.#2, it appears as though this engine came from and auto truck (you can tell by the somewhat square white plugs laying on the pallet, as was stated by others).
I have just completed this same swap (97 3.4 auto computer and harness into 93/94 manual), PM me and maybe I can help you out.
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Old Apr 13, 2010 | 06:48 AM
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dntsdad
the seller has only the engine and harness because he was planning on replacing the engine on his T-100 so he didnt need the ecu

alright the seller isn't going to be able to get me the pics until thursday... so ill have to wait until then to verify what is on the engine thanks for the info

with the plug differences in the 97 model will i have to source a manual harness from a 97 i want this thing to work the first time i try and fire it up. I dont want to mess with the engine harness in terms of splicing and stuff i know ill have to do a little already for the body harness
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Old Apr 13, 2010 | 04:59 PM
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motor to motor I do not believe there is a difference. Electronics and transmission I think are the only difference.
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Old Apr 13, 2010 | 05:47 PM
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so as long as the ecu and harness's years match ill be good?
Well it seems i might end up buying a different engine now. I found one for $950 out of a manual 97 T-100 with 62,000 miles on it! It just sounds way too good to be true he said they run each engine and compression test ect... before they sell it.

Last edited by RoBatt; Apr 13, 2010 at 05:49 PM.
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Old Apr 14, 2010 | 05:29 AM
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I guess we got lucky with our swap, we used a 3.4 with wiring harness from an auto, But bought an ECU for a manual (same year, same eng), but the ECU plugged right in, I just abandoned the wires for the auto that weren't needed, Spliced in hook ups for the speed sensor and backup light switch and it all worked fine.

I have read several places on here where some have said there were different crankshafts for auto and manual, but on one of the threads, a toyota technician said that all of the 3.4 cranks would accept a pilot bearing, that toyota only made one crank for these engines, there again we used a 3.0 pilot, clutch, p/p, and flywheel on our swap.

I have also read on here where some say that the ECU plugs for an auto and a manual are different, Maybe they were for some trucks and years??....anyone know for sure?

If you've got the chance to buy a 3.4 from a manual with wiring harness, go for it, i'm sure that will make things much easier....good luck with your swap, your gonna love the results!
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Old Apr 17, 2010 | 03:15 PM
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Originally Posted by kenpost856
I guess we got lucky with our swap, we used a 3.4 with wiring harness from an auto, But bought an ECU for a manual (same year, same eng), but the ECU plugged right in, I just abandoned the wires for the auto that weren't needed, Spliced in hook ups for the speed sensor and backup light switch and it all worked fine.

I have read several places on here where some have said there were different crankshafts for auto and manual, but on one of the threads, a toyota technician said that all of the 3.4 cranks would accept a pilot bearing, that toyota only made one crank for these engines, there again we used a 3.0 pilot, clutch, p/p, and flywheel on our swap.

I have also read on here where some say that the ECU plugs for an auto and a manual are different, Maybe they were for some trucks and years??....anyone know for sure?

If you've got the chance to buy a 3.4 from a manual with wiring harness, go for it, i'm sure that will make things much easier....good luck with your swap, your gonna love the results!
Was thumbing through an older Toyota 4x4 Owner mag the other day... according to the article that Dirty Harry (Wagner) did on a 3.4 swap with ORS, the wiring harness is same, manual to auto, starting in 98...

I do NOT know if this is true... but found it interesting. And I'm hoping it's true.
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Old Apr 18, 2010 | 08:34 AM
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the harness isnt the same, the plugs that mate into the computer are the same starting in 98
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Old Apr 18, 2010 | 01:43 PM
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Originally Posted by dntsdad
the harness isnt the same, the plugs that mate into the computer are the same starting in 98
Any chance if you know the differences? I suck at reading electrical diagrams..
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Old Apr 19, 2010 | 06:00 PM
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Here are the pics
looks like its an auto...
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Old Apr 19, 2010 | 09:31 PM
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Auto/Manual engines are identical, all accept a pilot bearing...

You'll have no problem using a manual ECU with an auto harnessed engine. You may have to swap a few plug ends and do some re-pinning though. You just basically ignore any wiring that used to be associated with the auto transmission, as the manual ECU doesn't care.

Used a 2003 4runner auto engine myself, and a 2001 taco manual ECU.
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Old Apr 20, 2010 | 07:03 PM
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Originally Posted by allnmstkn313
Auto/Manual engines are identical, all accept a pilot bearing...

You'll have no problem using a manual ECU with an auto harnessed engine. You may have to swap a few plug ends and do some re-pinning though. You just basically ignore any wiring that used to be associated with the auto transmission, as the manual ECU doesn't care.

Used a 2003 4runner auto engine myself, and a 2001 taco manual ECU.
Maybe true for post 97 era but not this one I am almost positive.
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Old Apr 21, 2010 | 03:29 PM
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Hmm I used a 97 auto engine with a 99 harness(believe they were universal plugs at this point) with a 97 manual ecu. I know for sure that it can be done. But you have to get the manual plugs from a 97, 96,95.5, (maybe 98) harness. The yard I got the computer from was helpful enough to get me plugs from a manual 96 harness. Since I didn't know the change over to universal plugs.
I am not sure when the switch happened either 98 or 99. But there was a switch to using universal plugs. They are all now plugs that look like auto plugs.
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