A Guide for connecting a 1G TT ECU to a 1G/2G NA harness

[Mr.3000]

Here is a little guide for people who have questions about connecting a 1G TT ECU to their 2G NA Harnesses. This is information that I have either collected through research or through my own personal experience. Much kudos go out to John aka J-GROOVE for his part in this info. Here we go:


Front O2 pin 55
Rear O2 pin 56

1st gen TT FED SPEC ECU with my '95 N/A harness.

At the O2 sensor:
Blue - Signal
white - ground
black - heater
black - heater

At the O2 connector
White - signal
black - ground
red - heater
black - heater

At the ECU
black - signal
green w/blue - ground
green - heater
black w/blue - heater

Those should be the colors that you should be looking for. You know how the old O2 sensor came from under the car? Well extend all of those wires up to the engine bay and that O2 sensor will be ur rear one. Once u have done that, make it so that the stock heater and ground wires also go to connect to the front O2 sensor's heater and ground wires. Then Cut the O2 signal wire from the rear O2 sensor so that it no longer travels under the car. Then lengthen that signal wire and run it through the firewall to the ECU and wire it into pin number 56 (Rear). Then take the signal wire from the front and lengthen it, run it through to firewall to pin 55 for the front. Now, if I recall correctly pin 55 is empty, I will tell you what to do about that in a second. To correctly install a TT ECU and have it not blow itself up in an NA car, you will need to cut a few wires. Cut the wire to pins 103, 109, 110 and 111. Those are for stuff that our cars won't even use. Here's a pic to aid in the explanation:



Now for hooking up the signal wires.... If there is a wire in the pins u can just splice in your new connection. If not, you will have to take a pin connector and the wire from one of the pins that are no longer in use (103, 109 etc) and swap it into pin 55 and/or pin 56 so that u can splice in ur signal wire. So make sure that when you cut those that you leave quite a bit of wire to work with. There are two different types of harnesses that I know of. One of them opens up real easy and one you can't open and can only slide the pin connector out. For the one that can't open, You need to press down on the metal clip thingy to get it out. I used a needle. I hope this helps......maybe it will get stickied. Peace,
-Mr.3000

[Mr.3000]

I made this because I have been getting alot of q's lately on how exactly to do this and also because I know that when I was doing this, I was having a hard time. If it wasn't for John, I would prob still be trying to figure it out. Lol!!

[J-Groove]

Nice write up, and thanks for the props.

Try to add this info tot he 3S wiki as well.

-John

[Mr.3000]

It is done as you requested my friend lol. Have a good one.

[green-lantern]

nice, good job!

[Jigzibit]

sorry i've been off the boards for a long time so this might be a stupid question. i have a 1995 SL with a TT conversion on it. so i can put a 1st gen TT ECU into my 95 SL "plug and play" with these pin/wire mods and get the benefit of a TT's fuel MAP?

Jon

[Mr.3000]

Yea if you follow this guide, it should allow you to hook up the 1G TT ECU to your harness. Just remember that you will lose your radiator fan so you will also have to wire in a Derale fan controller. You may also lose your AC fan like I did. The derale will also be able to control that.

[Mr.3000]

bump....

[igota20hpweed]

dumb question because the thread is about connecting 1g tt ecu to 2g harness. But would this work the same if i wanted to use my 2g harness and connect a 95 hybrid tt obdii ecu to it? I goofed up and bought a 99 ecu/harness and now have just learned about its ability to relearn quickly; thus, not allowing me to keep my tune. There's always something you learn while doing the tt conversion ...ah if i could do it over again i could save so much money However, if i could use my na harness with an obdII ecu, would i pass emissions? Damn the enviroment!!! HAHA. Another idea, could i use the 99 harness and plug up a 91-93 ecu since its 3 plug as well? Worst comes to worst i could just disconnect the 02's so i can keep my tune with the 99 ecu, supposedly this works.

[Miss3000]

Aww wow baby I didn't know you made this!! I'm so happy that you're helping others I find that really attractive in a man....
<3