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Where does this wire go to? I'd rather mot snip anythin but would like to see if this would make a difference.

what wire?

The wire that tells the ecu you the trans is an at or mt B48.20 according to vrg's chart

I believe it goes from the ECU out to one of the connectors behind the battery. I might be thinking of the jurisdiction ID though... not sure.

You don't have to snip it if you want to temporarily disconnect it; all the contacts in the ECU harness connectors are removable.

From what I remember of the MT/AT pin. Depending on what trans you have. It either gets a 5V from the ECU or 0V...ie disconnected.

Hmm, how are these released from the connector, is it like molex where you either need a special tool or a paper clip and a lot of finness?

safety pin will do it

MK

These connectors have dual detents. First you have to release the clip that locks all the pins on that row in place; two small slot-head screwdrivers can do the job. It's pretty obvious when you look at it up close.

Then you have to release each pin individually with some finesse and a very small screwdriver, a safety pin, or something similar. An actual contact extractor tool would be ideal, but these work. I go in from the side opposite the wire and lift the little plastic locking tab up, and then pull gently on the wire, usually with my mouth since both hands are in use.

The transmission ID pin is connected to the 5-volt rail inside the ECU through a pull-up resistor. So if the pin is left disconnected, the ECU will read a 5-volt signal and interpret it to mean the car has a manual transmission. If you externally connect the pin directly to ground, that'll "override" the pull-up resistor and the ECU will read a 0-volt signal and interpret it to mean the car has an automatic transmission.

So when you do a 4EAT-to-5MT conversion, you can just cut the wire and all should be well.

jawesome I'll try this today

good to know that didn't work. also I ended up just snipping the wire since I felt I could always go back and solder it otgether again if need be.

What didn't work?

Yeah, snipping the wire is no big deal... it just goes to ground on the car side anyway so you would even be okay if you lost the car side wire.

snipping the wire didnt work to fix the idling problems. so it's pretty much assured I need a 5mt ecu.

Oh.

Yeah.

In 1990 the 5MT and 4EAT ECUs were completely different.

Even so, it's good that you snipped the wire.

hmm, you think the 90/91 hitachi ecu I've got would work better now that I've snipped it? It was having problems with the hitachi maf I bought and my stock JECS IAC valve before I snipped the wire. Or would that stuff still probably be the same?

As a guess, I would have to say the Hitachi ECU would probably work the same as it did before you snipped the wire. It likely only knows how to operate in 5MT mode, and only knows how to drive the 5MT's IAC valve.

You could try it though, right?

If you can get your hands on a 92-94 5MT ECU or a 92 4EAT ECU that would be the way to go, I think. Or swap in a 90-91 5MT IAC valve and use the Hitachi ECU you have.

http://bbs.legacycentral.org/viewtopic.php?t=16774

Oh .

Cool.

Hm, I guess that means I'm doing a good job of cutting back my Legacy Central time commitment?

yes indeed

Sorry to bump an old topic but some of the info is still relavent. How the hell do you remove these pins? I got the locking clips up and stuck a paper clip in through the side opposite the wire and pulled on it. Nothing is happening. Do you have to push down on something or up or something. I'm hella confused.

A paper clip isn't very good for this purpose. A very small flathead jeweler's screwdriver works decently. I sometimes also use a large sewing needle.

You stick the tool into the end of the connector that the ECU pin normally goes through (i.e. not from the wire side). Just above each contact you can see a little plastic tab that's holding the contact in. You lift this tab up while pulling gently on the wire and the wire and contact should come right out the back.

I'm still not getting it. Do you have any pictures of the contact out of the connector so i can see what I'm trying to do? There's two holes for each row. One where the pin connects and one above it. Am I sticking something in the lower hole or the upper hole?

I don't, unfortunately, have any pictures or anything...

You're sticking the tool into the larger of the two holes -- the one shaped kinda like a "T."

It's hard, but try to look in through the hole and see the tab I'm talking about. It kind of looks like a little wedge.

OKay I get it now. The tab is way back there.

This actually easy once you know what you're dioing.

Yeah, it's hard to explain but once you do it the first time it all makes sense. Sorry I couldn't explain it better, but I'm glad you got it figured out now.