1991 Legacy Auto Gearbox problems

Flywheel, Clutch, Transmission, Axles, etc...

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1991 Legacy Auto Gearbox problems

Post by feeyam »

Hi all.

I've recently purchased a 1991 Subaru legacy 2.2 4wd. The previous owner informed me that he had changed the original 2.2 gearbox with a 2.5 gearbox.
The problem I have is that, when the gearbox is in drive, it does not change its gear automatically. If I put it into manual 1 and 2, it will drive and change in those gear, however, the 3rd gear is basically non existent and does not work.

Has anyone had any experience with this?
If the TCM was not changed to a unit that comes out of a 2.5, will that be causing an issue?

Any help would be appreciated. Thanks.
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Re: 1991 Legacy Auto Gearbox problems

Post by Legacy777 »

Hi Faheem,

There are two generations of 4EAT, automatic transmissions that Subaru used. You can tell by the electrical plugs on the transmission. Take a look at this post for the difference.


If a second gen 4EAT transmission was used I would be curious to see what was done to make the electrical connector work with the phase 1 wiring. That's probably where I would suggest starting and see what was done. If you can find out any information and take any pictures that would be helpful in diagnosing things.

PS: I'm going to move your post to the Drivetrain forum as it's a better fit there.


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Re: 1991 Legacy Auto Gearbox problems

Post by wtdash »

Edit: All the below is based on USA info. I'm not that familiar with Subarus from other countries.

The top of the transmission bellhousing will have an ID tag (or should) that starts with TZxxxxxxx. This can be used to Identify the transmission.

Like this: http://www.subaru-svx.net/photos/files/TE1221/32288.JPG

As noted by Josh, the 2.5 should run on the same TCM/TCU (computer), if Phase 1. But once you ID the transmission it wouldn't hurt to swap the TCM - although I can't promise the TCM's connector plugs are the same.

Another issue could be the final drive ratio (FDR). The '91 2.2 had a 4.11 FDR; whereas all the '96-'98 2.5 Subarus had a 4.44 FDR for their automatic transmissions.

Also, is the POWER light blinking when key is 1st turned on? It'll flash 16 times to notify of a stored code in the TCM - not the actual code.
See Josh's info here: https://surrealmirage.com/subaru/trans.html

Good luck,
Turbo Subies:
'87 GL-10 Turbo - SOLD
'90 BJ EJ22T/DOHC & 5speed swap - SOLD
'04 FXT, Forged internals, VF39, STI TMIC, Cobb AP- SOLD
'93 Legacy SS - 5-speed, SOLD :-(
'96 BD-turbo'd-SOLD
'98 SF - NA-T
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