1G 90 to 91+ PTU swap

[Joshua Tadich]

Can someone post a link for a ptu swap from a 90 to a 91-99 PTU swap? The ones I found are confusing as hell with people arguing about how to do it. Thanks. I suck at wiring.

I also have a spark tech COP setup I'm doing as well if that makes a difference.

 

[DSMPT]

So your car is a 90 and want to use a 91+ PTU? Do you already have a pigtail for the 91+ PTU?
IIRC, just connect the same color wires between the 90 harness and 91+ pigtail. You don't use the 91+ pig tail's White and the Black/White wires in a 90.

 

[Joshua Tadich]

Yes my car is a 90 and I have the 91+ PTU and pigtail already. The 90 ptu is a 5 wire where the 91+ is a 8 wire but only uses 7, none of those wires match up in color but I think I found the right diagram to do it. Also I have spark tech COP I'm putting in as well. The 90 harness for the coil is a square 4 wire connector which has a white tach wire, black/white, yellow/black, yellow/green, the 91+ is a 3 wire triangular connector black/white, blue/black, blue/red. The colors do not match at all.

 

[19Eclipse90]

91+ Power Transistor with 90 ecu

 

[Joshua Tadich]

That is the thread i used to figure out the PTU. Where I'm at now it the coil pack plug. I know the white wire is for the Tach. I'm sure the black/white wires connect but where does the yellow/black and yellow/green go? Is it yellow/black to blue/black and yellow/green to blue/red? Or is it yellow/black to blue/red and yellow/green to blue black? Then where do I tie in the white tach wire?

 

[1990TSIAWDTALON]

I am not sure that the tach works after the swap. Was there a reason to swap from the factory setup? I use the 90 PTU on my cars but run a ARC2 box on one, just not a COP setup as the stock system is pretty stout.

 

[Joshua Tadich]

90 PTU is junk. Either way even if I kept ptu the same I'd still have to swap to the 3 wire COP plug. I know theres a way for the tach to work, i read about it but cant find the post on it. The one I think it is has a bad/expired link now.

 

[1990TSIAWDTALON]

I have to disagree on the 90 PTU being junk unless you are talking about your unit. I have 4 running 1990 dsm's and all have the 90 PTU, some with other mods, some stock. All run fine but I don't run a COP setup, that is a personal choice and I don't need them with my setups. I know there is a thread about how to wire the COP for a 90, I will search around and see if I can come across it.

This may be of help for you or it may be one you have already read...............
https://www.dsmtuners.com/threads/cop-wiring-for-a-90-cop-came-from-a-91.469891/

 

[Joshua Tadich]

Yea I read that one. I honestly just suck at wiring, well I'm not confident is more accurate. See pictures below. I'm positive the black w/ white stripe wires go together. Can you tell me which of the other 2 go together? Once that is done I know theres a way to get a tach signal because i read it and had it in my old 90 like 12 years ago.

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[1990TSIAWDTALON]

I honestly would try what you have in your last picture, but make it a temporary in case they need reversed.
Black I would assume is ground and the other 2 are power with the white being tach like you said.

 

[Joshua Tadich]

Can anyone point me on how or where to connect my tach wire? I for some reason think Its a wire on the PTU

Can I somehow wire in the tach interface in the picture attached.

 

[Joshua Tadich]

Ok I think i got it. Heres what I found
1990 4 wire plug
Black/white = ground
White = tach
Yellow/green = 1&4
Yellow/black = 2&3

91+ 3 wire triangular plug
Black/white = ground
Blue/black = 1&4
Blue/red = 2&3

I'm going to wire in my tachometer from my 90 coil pack between the COP and the factory harness. See picture.

I think I'm gona try and build a patch harness for this to make it easy on everyone else ......if it works of course

 

[Joshua Tadich]

Ok so I got everything hooked up and running properly. My above post with the wire description is correct. Black/white together, Yellow/green to blue/black and yellow/black to blue/red I also removed my tach interface from my 90 coil pack and ran jumper wires to it. I depinned the 91 pigtail and added pins to where I cut off the connector from my 90 harness. I tied jumper lines for the tach interface right into the pins themselves. (See attached pic above for tach interface) Car is running smooth and the tach works like it always has. Hope this thread can help out the next guy. Time to swap out my CAS(I built my own harness for this one, so theres no splicing at all)