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No AWD – help!


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36 replies to this topic

#26 Legacy777

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Posted 20 January 2004 - 09:38 AM

Dave,

post the part # on the TCU, and I'll check to see whether it's a FWD TCU or not.

#27 dashton

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Posted 20 January 2004 - 02:38 PM

Josh,

Here are the part numbers off the TCU:

EE
31711 AA911
A64-000 822

Which part of the number determines if it's 2WD or AWD? Do you have some type of decoder you could post?

I forgot one thing to check - I tested all the inputs to the TCU and they all are in spec. But I checked them all to a common ground - oops - need to check them to their specific grounds through the TCU. Could have a bad ground that's ruining a good signal. Another project for tonight. Thanks. Dave

#28 Legacy777

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Posted 20 January 2004 - 08:45 PM

This is the part # 31711AA911

I have a complete parts book for the 1990-1994 legacies. It has application guides and other very helpful and useful stuff.

That TCU is definitely used in the AWD legacies 1990-1991 to be exact.

Definitely check the grounds.

#29 ajs70

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Posted 25 June 2009 - 02:57 PM

Hi,
I have similiar problem, my 1998 RS only work in fwd, but I have the fuse in because when I take it out it only shifts from 1st to 2nd and when it tries to shift into 3rd or 4th it justs revs no power to any wheels.
It has a 31711 ad800 tcm,is this for a 1998 2.5RS only?? Is there any other tcm I could put in that would work??:-\
Regards,AJS70

#30 Legacy777

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Posted 26 June 2009 - 09:22 PM

That TCU is listed for the the EJ25D. Other TCU's will probably work. They're programmed for shift points and agressiveness. The 2.5 RS TCU is probably a little more agressive then say a regular impreza or legacy.

#31 ajs70

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Posted 27 June 2009 - 07:01 AM

Josh,
Thanks for replying!
So could I use a Tcm from a 2.5 leg gt for example to get more aggressive shifting? Do you think that would be a good alternative? If so do you have a couple of alternative suffix #'s for the 31711 that might be good choices:)??
Thanks in advance AJS70

#32 Legacy777

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Posted 28 June 2009 - 04:44 PM

You would probably be best off staying with the same model line. You may be able to use a Legacy TCM, but I kind of doubt the TCM connectors would be the same.

#33 daddycoolj

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Posted 28 June 2009 - 04:45 PM

Maybe this is a virus. I have a 90 legacy wagon with the same problems. Mine seems to skip a gear when it shifts, then it will downshift in a few yards.(like it goes from first to third then back down to second.) only the front wheels have power, but it has torque bind. It doesn't have air suspension. I've tried the fwd fuse trick and the torque bind goes away. when the a/c is on the symptoms are worse, and it idles rough. when i got the car most of the instrument panel screws were out and wires unplugged. There seems to be a lot of "shared" circuits in these cars. I'm thinking of going the loose wire route. I'll report my results soon.

#34 stokie7

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Posted 08 October 2014 - 05:34 AM

I’m reaching my wits end with the AWD system on my ’90 legacy wagon and I’m looking for any advice I can get. It’s got an auto trans and runs great, but I can’t get the computer to active the AWD. Here’s what I’ve done:

1. Removed the extension housing from the rear of the trans and replaced the seals in the tailshaft. No observed damage or wear.

2. Put a switch in the line to the trans duty C solenoid. If I push the switch and break the connection, it locks up the rear axle and puts the car in 4WD – so I know that mechanically it’s sound.

3. Put a different trans computer in. No change – still no AWD.

4. Checked the voltage going from the TCU to the duty C solenoid per the info in Legacy777’s website. The voltage is ALWAYS at 9v+. Even when I put it in “1” and push the throttle to the floor. According to the spec sheets it should go to 0 in that condition. Also verified that there’s NO fuse in the AWD switch.

5. Checked for transmission code errors. The only errors I’ve ever found are for the duty C solenoid when I break the connection.

Last night I left the voltmeter connected and took it for a drive in the snow. Got it stuck with the front wheels spinning and still no voltage change. It’s almost like there’s something telling the computer to keep it in FWD. As soon as I pushed the switch and broke the connection it dug itself right out of the snowbank, so I know it should work.

The only thing I can think of is that I could have a bad speed sensor in the speedometer or extension housing, but wouldn’t it still try and lock it up with the shifter in “1” (per the shift map)? Also – if the computer senses a bad speed sensor shouldn’t it set a code?

The only thing I’ve messed with electrically on the car is the height control system. I’ve removed all the stupid air struts and replaced them with regular ones. I don’t see how this could affect it, but I’m just wondering ‘cause now all those connectors are disconnected. And I don’t think the AWD was working before I replaced them.

Anyway – I think I’ll head back to the junkyard tomorrow and try and find a speedo unit to mess with, and maybe exchange the computer for another one, but in the mean time I’d really appreciate any advice. Thanks. Dave

Hi Dave,

I know this is a 10 year-old post, but I joined Ultimate Subaru after reading some very helpful info from you.

Here's hoping you're still around...

I've got a 1998 AWD Legacy Lancaster auto (I think it's the Japanese version of an Outback) and I have front wheel drive only. I've tried putting the FWD fuse in, I get the FWD light on in the dash, but no change.

One clue is that if I accelerate hard I occasionally get a thump and a quick momentary change of attitude in the car, almost as if the rear drive kicks in for a second.

I can't see or hear any evidence of mechanical damage inside the transfer case, and the driveshaft turns the rear wheels fine by hand.

When one side of the car is jacked up and I put it into (any) gear, only the front wheel turns.

Any advice to get the 4WD working again would be greatly appreciated.

I suspect someone has figured out a way of switching something to enable 2WD on the road, saving fuel, and 4WD off road.

Cheers,

Rick.


Edited by stokie7, 08 October 2014 - 05:35 AM.


#35 CNY_Dave

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Posted 08 October 2014 - 04:42 PM

I would say you want to pull the wire that goes to the Duty C solenoid, that should fully lock it under normal circumstances.



#36 stokie7

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Posted 10 October 2014 - 07:00 AM

I would say you want to pull the wire that goes to the Duty C solenoid, that should fully lock it under normal circumstances.

Yes, I'd like to try this, have you got any suggestions as to how I'd find or access this wire? The multi plug that goes into the transmission has a few wires into it, would you know which one I'd be looking at? I'm thinking of connecting 12 v to the one going to the solenoid to see if it clicks in or out. I'm thinking it may be stuck in the bypass position.



#37 CNY_Dave

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Posted 10 October 2014 - 04:57 PM

You can just disconnect the entire connector (the one with the wires that go down the side of the trans with the trans dipstick) and it will default to 3rd gear and full AWD.






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