'91 2.2 legacy transmission swap to '97 2.5 transmission

[rt 2 mailman]

I have  a '91 postal Legacy with 220,000 miles that I use daily on a mail route, which developed a wine in the front differential, so I decided to change it out for a 75,000 mile used one. I've put in a '97 transmission from a 2.5 engine onto the  '91, 2.2 engine as told by seller this tranny was ok for my aplication. (changed flex plate,and shift harness to 91) left side wire harness plugs in but wires are different. It shifted fine but was stuck in AWD. I tried to put power from FWD fused block ,no change. Brought power from fuse block to what I thought was the wire for the transfer clutch solenoid. Drove it and still in AWD now does not shift, seems to be in 2nd gear. What do I do now?

[porcupine73]

First you need to compare the ratio (3.9, 4.11 etc) of your differential to that of the transmission you put in. If they're not the same then it would cause what you describe. There is a way to tell from the transmission serial numbers (though I don't know what it is).

 

Whatever happened where it is now stuck in 2nd gear sounds like 'limp mode'.

[rt 2 mailman]

Gear ratio is the same 4.11, so I was told by "Foreign Engine Exchange" who sold me the transmission. Cleared codes by taking off the + cable,

 

now shifts as before, but still stuck in AWD. I don't believe it to be a mechanical problem because when I turn tight just before shutting off the car, I

 

can feel the car "relax or unbind" when off (power off to transfer clutch solenoid). I know the the wire harness is different in the '97 than on my '91

 

 although it does plug in ok. I just don't know which wires to splice to properly energize the transfer clutch solenoid. Currently snow on the ground

 

here, but when this all melts this binding will not be good for this transmission. Thanks for your feed-back, but still looking for more.

[porcupine73]

Ah ok, I've never swapped a trans. Maybe you already did this, did you try just putting a fuse in the FWD holder? It doesn't really provide power to anything, it's actually a ground input to the TCU, then the TCU controls the duty c transfer clutch solenoid. (It doesn't actually energize the solenoids completely, it's something like a 50Hz square wave varying from 5% to 95% duty cycle). The relaxing or unbinding when turning it off is probably from loss of line pressure? Sounds like you probably need some wiring diagrams to compare possibly. Not sure if the postal had anything special about it in this regard.

[rt 2 mailman]

I did put in the fuse and got no change. There was a small amount of voltage on one side of the fuse,so I took that power to what I thought was the wire (on the transmission side of the plug) that went to the duty solenoid and put it into "limp" mode. Yes I do need a wiring schematic for the transmission plug for a '91 and '97 Subaru Legacy L (same as postal) then splice in the '97 to match the '91 and hopefully all will be well. I haven't been able to find those diagrams anywhere, does anyone know where I can find them? When I guess at which wires are the right ones I'm afraid I might ruin the TCU as I thought I did when I put it into limp mode. Thanks for your help but I still need more.