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Transmission swap done.. but have problems..help


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I have a 1990 Legacy L with a bad AWD automatic tranny. So I found a 95 Legacy LSI donor car. The donor cars transmission was flawless. No torque bind, shifted fine, etc... I confirmed the final drive ratio for the two years to both be 4.11. So I installed the transmission into my 90.

 

Started it up, runs, shifts good, but I'm having rear end problems. Any slight corner the rear end binds. If I floor it on the grass in a straight line the rear end will chatter. I installed the FWD fuse and it stays in AWD, and the symptoms persist. So I thought maybe the computer was different. I put the 95 computer into the 90... that made it worse and won't shift out of 1st. Maybe there is a separate control module I don't know of that needs to be swapped.

 

I thought maybe the rear ratio was wrong so I swapped in a 3.9 just for the heck of it. That was even worse.

 

So I'm at a loss. I'm growing tired of working on this thing. Any help would be much appreciated!

 

Thanks

Jeremy

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Do you have any wiring diagrams?

 

You need to check the pin outs for the two TCU's to see if any pins are different. It's possible things are different, which is why you're having issues.

 

Also, you need to make sure the connections are the same at the connector that hooks up to the transmission.

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first thing first, i am assuming all the tires match and are inflated the same. When you put the awd fuse in does the prblem go away. Next make sure all the wires to the tranny or good, none are brken, and there is continuity across all plugs. If it doesnt go away i would look at everything going to the transmission. I am showing two differnt kind of connectors, one for an "early model" (pre 95) and one for after. One is a box, one is rectangle. If you adapted one to the other check the wiring, could be the car thinks its in low electrically. Manual gear selection is mechanical not electrical. gear selector switch is for the benefit of the computers and the neutral saftey switch (i think). Are the reverse lights on at anytime in a drive gear?

The system basically uses 2 vss sensors, a wot switch, the gear selector, and the duty c solenoid. Were both trannies equiped with cable driven speedos? Can you get a hold of the TCU from the doaner car? Just for the hell of it, jack up one rear wheel of the car (car in neutral brake off wheel chocked) and see if you can turn the wheel. If not jack up both sides, the wheels should turn in opposit directions.

What were the original symptons. i am concerned to it showing up on minor turns. this means the car is either locked in 50/50 split (no power to the duty solenoid) or a bad differential (very rare if its not lsd).

Sooby regulates the awd up to 20% speed differnce between front and rear axles, then it will start manipualting the AWD. This is done to allow for speed differnce on turns. It sounds like you dont even have that.

Other times the car is in 50/50 split, WOT, and when the car is in low.

As i type this out i think you have wires crossed someplace.

 

nipper

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The 95 tranny plugged right into the stock wiring harness on my 90. But I don't have the schematic for the wiring. Looks like I'll have to find that. Josh do you happen to have those scanned?

 

Nipper some of the questions you asked were already answered in my first post.

 

Fwd fuse does nothing

Tires are the same

Reverse lights work only in reverse

95 had a electronic speedo and the 90 is cable driven

Tired TCU from donor car. Did not help

Rear diff is fine

Wires crossed? Quite possible! :)

 

Thanks for the help Nipper. I'll get right on some of your suggestions.

 

Looks like I have some wiring issues to figure out.

 

Jeremy

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The 95 tranny plugged right into the stock wiring harness on my 90. But I don't have the schematic for the wiring. Looks like I'll have to find that. Josh do you happen to have those scanned?

 

Nipper some of the questions you asked were already answered in my first post.

 

Fwd fuse does nothing

Tires are the same

Reverse lights work only in reverse

95 had a electronic speedo and the 90 is cable driven

Tired TCU from donor car. Did not help

Rear diff is fine

Wires crossed? Quite possible! :)

 

Thanks for the help Nipper. I'll get right on some of your suggestions.

 

Looks like I have some wiring issues to figure out.

 

Jeremy

 

Sorry about not seeing some of those. Here is another question. Did the spedo cable fit into the same place as the original vss sensor? i'm curious about that one.

 

nipper

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Hey Nip, what if the electronic speed sends a VSS signal to the tranny control? Now you don't have the proper control and there is no provision for the proper signal. The 95 CPU wuld not wrk because it still is not getting a signal for speed.

I don't really have info on Subie's auto set up, I'm just going on how it works on some BMWs I am familiar with. Without the VSS signal on a BMW there are several problems you can have from mixture to cruise and even the radio ties in.

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Hey Nip, what if the electronic speed sends a VSS signal to the tranny control? Now you don't have the proper control and there is no provision for the proper signal. The 95 CPU wuld not wrk because it still is not getting a signal for speed.

I don't really have info on Subie's auto set up, I'm just going on how it works on some BMWs I am familiar with. Without the VSS signal on a BMW there are several problems you can have from mixture to cruise and even the radio ties in.

 

 

One VSS seinsor is in the tranny, in pre 95's the other is in the spedo head, 95 and older its in the rear of the tranny. Now i dont know if there is a differnece between signal pulses of a pre 95 and post 95. I dont think there is. If you loose a VSS for any reason, the AWD will not activate, and you will have FWD only, and some light on the dash throwing a hissey fit.

 

Maybe this will help

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/

 

nipper

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Sorry about not seeing some of those. Here is another question. Did the spedo cable fit into the same place as the original vss sensor? i'm curious about that one.

 

nipper

Yes, it fit with no problems

 

Interesting concept with the speed sensor though. With the 95 computer the At Oil Temp light would flash really fast. And the tranny would not shift out of 1st unless I manually put the shifter into 2nd.

 

With the 90 computer I get the power light doing it's 16 flashes at start up. I'll check those codes as soon as I connect the manual button back up.

 

Thanks for the link.

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Yes, it fit with no problems

 

Interesting concept with the speed sensor though. With the 95 TPS the At Oil Temp light would flash really fast. And the tranny would not shift out of 1st unless I manually put the shifter into 2nd.

 

With the 90 TPS I get the power light doing it's 16 flashes at start up. I'll check those codes as soon as I connect the manual button back up.

 

Thanks for the link.

 

 

There you go, i do beleive its telling you the duty c solenoid has failed for some reason. If that solenoid fails, you get 50/50 split all the time. The solenoid has to be energized to regulator/dump pressure from the AWD clutch pack.

 

nipper

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  • 2 months later...

Finally a conclusion to this problem. After a few months of trouble shooting I found that my TCM was shot. Found a new used one at the junk yard.. popped it in and torque bind is gone! Thanks for everyone’s help with this problem.

 

~Jeremy

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been keeping my eyes open for interior stuff mainly,

 

driver-door.jpg

passenge-rear-seat.jpg

 

previous owner was a smoker, your donor car doesn't have grey interior does it? also on another note, can you remove that upholstry from the door panel or is it all one piece? i've not taken mine off yet (dont have a garage or driveway to do it in) and i was always curious if i could just find the fabric somewhere to replace, or if i have to replace the entire panel.......

 

also, looking for cupholder, center console latch, anything to make my ac/heater lights operate, only about half of the lights work, tweeter upgrade behind the side mirrors as well

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burn marks you can't do much about but replace, yes the cloth panel comes out after you remove the door panel.

 

and on the sedans, the rear seat bottom, (top too for that matter) is extruded formed foam, covered by the cloth. almost no metal in them. i just had mine out, i was giong to replace, but instead, i hosed them down, scrubbed them , hosed them and then stood them up to drip dry. you wouldn't beleive the "cola" that came pouring out of them.

 

they look pretty good now.

 

 

 

been keeping my eyes open for interior stuff mainly,

 

driver-door.jpg

passenge-rear-seat.jpg

 

previous owner was a smoker, your donor car doesn't have grey interior does it? also on another note, can you remove that upholstry from the door panel or is it all one piece? i've not taken mine off yet (dont have a garage or driveway to do it in) and i was always curious if i could just find the fabric somewhere to replace, or if i have to replace the entire panel.......

 

also, looking for cupholder, center console latch, anything to make my ac/heater lights operate, only about half of the lights work, tweeter upgrade behind the side mirrors as well

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