legacycentral bbs

Hi, I just recently purchase a 1990 Legacy LS Wagon, 4WD, 4EAT.

I was told by the previous owner, who took it to a tranny shop, that the transmission was a JDM 4EAT.

How can I determine if this is the case?

It has some issues shifting, if its in D, even babying it from a start it wants to roll up to 4k or so before it will shift. If I put it into 3 and Manual Mode it will shift a bit more normally, maybe only revving up to 3k. I'm also not sure if its ever going into 4th. At highway speeds of say 60 MPH I'm at around 3.5k.

The CEL was on, but after checking the error codes, it seemed to clear and is no longer on. I checked the TCU trouble codes, both stored and current, and just getting the constant flashing, that everything is OK.

Could any of this be from an incopatibility of a USDM TCU and JDM 4EAT? How can I tell if I have a JDM or USDM TCU?

Any insight would be great. Thanks, John.

You could try looking up part numbers for USDM TCUs in online catalogs. Also see if the large 2 letters on the label match up to anything.
Google the number of your TCU and see what pops up?

Yes, it could have the wrong tran ecu and it could cause changing speeds to be strange.

I have had one like that and after checking everything else I changed the trans ecu and it was heaps better... I could put my foot down and use the torque without it always reving.

Ok, so pulling some numbers off the car:

TCU:
Big Letters: GJ
Number: 31711 AB394
Second Number: JA64000 RL5 2228

From a couple of hits on a google search, this seems to be out of a 92.

Transmission:
Number: TZ102ZA2AA-MH

According to this site: http://www.prosubaru.com/tech/transid.htm its from a 1992 to 1994 model. While I don't think that this is necessarily a JDM 4EAT its certainly not the original, as the VIN tranny code is TZ102ZA1AA.

Rear Differential:
Number: 27011AA151
Ratio: 3.900

Do you think it would be worth trying a new junkyard TCU to see if the shift issue persists?

I was thinking of adding a "Power" mode switch as has been discussed in these forums. I could see what effect if any that has as well.

Would a presumably stock 1990 ECU have trouble talking to a 1992 TCU?

Hmm. My parts book says that your chassis plate trans number..
TZ102ZA1AA, is only for a 91 model 4Wd turbo. Nothing else had that trans.
The TZ102ZA2AA-MH you have fitted fits a 4WD sedan non turbo or a 4WD station wagon non tutbo or turbo. It does 92, 93, 94 models but not 91.

That trans ecu you have is not in the book at all.

Simplest thing would be to go to the wreckers with the dash already apart and tell him that you want a trans ecu but can you test it to be sure it is going to cure the problem before you commit to buying. Plug their one in and test it out.

Hmm. My parts book says that your chassis plate trans number..
TZ102ZA1AA, is only for a 91 model 4Wd turbo. Nothing else had that trans.
The TZ102ZA2AA-MH you have fitted fits a 4WD sedan non turbo or a 4WD station wagon non tutbo or turbo. It does 92, 93, 94 models but not 91.

That trans ecu you have is not in the book at all.

Simplest thing would be to go to the wreckers with the dash already apart and tell him that you want a trans ecu but can you test it to be sure it is going to cure the problem before you commit to buying. Plug their one in and test it out.

If you want to try some other TCUs, I have a couple I'll sell.

Some new information to toss into the mix:

Added a manual override 'Power' mode switch as described in this thread:
http://bbs.legacycentral.org/viewtopic. ... c&start=25

The switch seems to function as described, flip it, grounding pin 4 and it lights up the power button, raises the shift points.

Except on top of my previous problem with the already high shift points, even when babying the thing, it's raised the shift points even higher, to the point where it wouldn't shift out of first gear in D when i was at 5k or more.

Another curious thing: in the thread describing the manual power button it says that the pin 4 slot in the connector where you are inserting a wire to ground should be empty. On mine, pin 4 was filled with a teal blue wire. I snipped it in half, and wired the side that went to the TCU to my power switch.

Could anyone with a JDM legacy confirm the color of the wire in pin 4 of connector B46 on their TCU?

Any thoughts on the high revving shift points? How to bring them down? What's causing it?

At this point I'm still thinking of trying to track down a junkyard 92 to 94 TCU and swapping to see what happens.

----
John