Non-Engine Bay Emissions equipment / Under Driver Seat Connector

[Atuca]

Ok, next connection...

Here is the underseat harness with 5 wires from the automatic:

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00183.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00183.jpg" border="0" alt="Underseat harness"></a>

The 2 blue wires (blue w/red stripe, blue w/white stripe) connected to the small ECU plug, in between the 2 yellow wires and the yellow and pink wires:

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00184.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00184.jpg" border="0" alt="Photobucket"></a>

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00185.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00185.jpg" border="0" alt="Photobucket"></a>

The green w/yellow stripe wire ties in to the same colored wire a little ways up from the second largest ECU plug:

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00186.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00186.jpg" border="0" alt="Photobucket"></a>

The red wire ties in to the harness at the same point as the red wire coming from the O2 sensor and combines with the red wires coming off of the largest ECU plug.

The black wire ties in with a black wire that, in turn, joins in with the green-encased black and white wires from the O2 sensors.

These wires are not present on the harness from the manual transmission car. Can anybody help me identify the purpose of this connection please?

So on my 99 Eclipse GSX (manual tranny) I only have 3 wires, but the same plug it looks like.

From back of plug:

[ ]----------------------------[ ]
[ ] [Gr/Y] [Blue/White ] [Black ]

It follows the same route as below

OK, so I traced the wires around the cab of the car:

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00187.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00187.jpg" border="0" alt="Photobucket"></a>

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00188.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00188.jpg" border="0" alt="Photobucket"></a>

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00190.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00190.jpg" border="0" alt="Photobucket"></a>

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00189.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00189.jpg" border="0" alt="Photobucket"></a>

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00196.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00196.jpg" border="0" alt="Photobucket"></a>

And here's where I ended up:

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00192.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00192.jpg" border="0" alt="Photobucket"></a>

Here's the offending wires (blue/white, blue/red):

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00191.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00191.jpg" border="0" alt="Photobucket"></a>

So now I have to chase this down the rabbit hole:

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00195.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00195.jpg" border="0" alt="Photobucket"></a>

Anybody know what all this connection controls?

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00194.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00194.jpg" border="0" alt="Photobucket"></a>

Or does this mean anything to anyone?

<a href="http://s292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/?action=view&current=DSC00193.jpg" target="_blank"><img src="http://i292.photobucket.com/albums/mm4/ducducgoosed/GS-T%20conversion/wiring/DSC00193.jpg" border="0" alt="Photobucket"></a>

According to my 99 factory wiring diagrams: The blue-red (ECU pin 55) goes to pin 2 of the evap emission ventilation solenoid. The blue-white (ECU pin 61) goes to pin 1 of the fuel tank differential pressure sensor.

Now I can't seem to find any other info on this plug, this sensor, what it does, where it is, and if it can be removed from a car that is used on the track only. This is part of my interior rewire, so obviously removing plugs is a good thing! I THINK this sensor was part of the gas cap check they do at the smog station.

Can I remove these wires, and does the ECU need the pins mentioned above? Its only seems to make perfect sense to remove all the sensors from the engine bay as well as the back of the car!

Thanks!

 

[turbosax2]

Regarding the fuel tank differential pressure sensor:

That's only used on the '99 (and possibly '98?) ECUs. It's completely unused on the '95-'97s ECUs.

Since you have an eprom ecu you can ditch it. As further proof, I haven't had that plugged in since I've started and driven my car and it hasn't thrown any CEL's or caused any issues I'm aware of. I'm going to removing mine too.

 

[Atuca]

Well you weren't supposed to answer this question! I was trying to figure it out and this was my secret plot to figure it out to help you!

Anyways, glad you got some more info on this plug, but by any chance do you know where the sensor actually is, and if it is removable?

 

[turbosax2]

No, sorry. I'm not going be touching the wires on the interior harness side so I didn't bother tracing them back. I'll just be removing the wires from the ecu harness and tuck the interior connector under the seat.

 

[Atuca]

Alright well I removed the wires just to the plug at the fuel pump, I didn't remove them or bother chasing the wires to their source under the car, I think I would have to drop the fuel tank to reach them, I couldn't see anywhere where I could follow them anyways.

I am still curious if anyone know what the sensor is supposed to do, and why it wasn't there on 95s and why it is there now.

Why couldn't we have made friends with DSM/Mitsubishi Engineers?

 

[ghostwritr]

Alright well I removed the wires just to the plug at the fuel pump, I didn't remove them or bother chasing the wires to their source under the car, I think I would have to drop the fuel tank to reach them, I couldn't see anywhere where I could follow them anyways.

I am still curious if anyone know what the sensor is supposed to do, and why it wasn't there on 95s and why it is there now.

Why couldn't we have made friends with DSM/Mitsubishi Engineers?

Well, as you have all of my pics in this thread, I figured that I would add some more to clear this issue up...

I had to put this project on hold for quite a while, but got out to the garage today & traced down the offending wires the rest of the way.

You must be logged in to view this image or video.

In breaking out the wires from the tape, I was able to find that the wires in question went 2 places:

First, this plug:

You must be logged in to view this image or video.

Plugged into this connection on the tank:

You must be logged in to view this image or video.

Which is Mitsubishi part# MD322973, otherwise known as the fuel tank pressure sensor.

Second, to this assembly, found behind the gas tank:

You must be logged in to view this image or video.

Where this plug is found:

You must be logged in to view this image or video.

So, it would appear as though this is all emissions related. But the questions still remain of whether it is all necessary to pass emissions testing & whether it is worth splicing the wires into the harness that I am putting in the car...

By way of comparison, here's a pic of the gas tank wiring in my 1997 Spyder GS-T:

You must be logged in to view this image or video.