Auto tranny missing gears

[gonesh]

Quick question.
I'm looking at a friends 94 3000gt - DOHC - Auto tranny.

It drives fine whether in sport or economy mode if you are accelerating slow or moderately. But if you punch it, it accelerates fine until it's time to shift - then it hits neutral and pegs the rpm's. If you let off the pedal it drops back into gear and rides perfectly fine. There MAY be some shudder at highway speed when maintaining speed, indicating possible overdrive (end clutch) issues, but it has some front end issues and I noticed some shudder in the 40 mph range too. I don't think that's the main problem at least. It seems like it will miss any *next* gear under hard driving, but I've only done it from a rolling start so far.

Question is - am I pretty much looking at clutch issues - ie rebuild - or can the TCU cause the tranny to miss gears? An inspection of the TCU caps and board showed nothing concerning, but I know it doesn't have to.

Side question - I've read that you can read tcu codes with an analog meter, but I haven't seen anyone say how or point to a code diagram. Anybody have the 411 on that?

[stealthee]

To pull TCU codes

http://www.plymouthlaser.com/tcucodes.htm

[gonesh]

To pull TCU codes

http://www.plymouthlaser.com/tcucodes.htm

Good deal. That will be handy. Thanks a bunch!

[stealthee]

I just now realized you are asking about a 94. The connector will be different. 94 and 95 connectors look like a OBD2 style connector, but are still technically OBD1.

The 94/95 connector is



I can't seem to find what each pin corresponds to, but I am sure someone else can step in with that info.

[gonesh]

That's awesome. The picture which I think should show that connector is missing from the page you linked - but it does say to use pins 6 & 4. I just had to figure out how the numbering worked.

[gonesh]

Well - it's done for now. I believe a rebuild is in it's future because I did reproduce the missed shift. But only once since the first drive where I could almost cause it at will. The issue my buddy was having where it did not go into gear at all, or went in but had NO power at all was caused by general dumbassery. In the bundle of wires I mentioned before, I found three wires that had been previously repaired - they used heat shrink tubing. And that's literally ALL. The wire were just overlaid and shrink tubing shrunk over them. They weren't even twisted together. Fixed that properly and it seems a lot better. We're going to get a few miles on it as it is and re-evaluate.


3000gt wires.jpg