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Intermittent Torque Bind -- is this probably a "Duty C" solenoid?


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#1 northgeorgiaroo

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Posted 10 July 2007 - 09:21 PM

Recently undented and resealed a dented transmission oil pan on a '90 Legacy wagon 4EAT.

While it was off, changed out about 6 qts of old, dirty trans fluid and this seemed to fix my torque bind.

A few days later, it was back. Primarily when backing out of a parking space. At this point the "power" light on the dash was flashing for about 5 seconds after startup.

Then, it was GONE again, and the power light stopped flashing.

I didn't get the code from the transmission (I read a post on how to do it, parking the wagon with transmission warmed up, then cycling through the gear selector while turning ignition on and off. I just couldn't get it to work :confused: .

Had to make several short trips this evening, and I swear I heard something whirr in the tranny at the end of the trip while parking, and it seemed to bind a little when I parked. I turned it off, then immediately restarted the engine -- yup, power light flashed at me -- I think it was laughing too!:Flame:

Next trip, though, no bind, no light!

What is most likely to cause torque bind to do a Houdini act!?

As I mentioned in a previous thread, I am not entirely sure I am up to opening up a transmission. I am willing to give it a shot, though, if a replacement solenoid can be had for not too much, and the alternative is forking over a grand to a mechanic.

#2 OB99W

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Posted 10 July 2007 - 10:42 PM

The thread title is "Intermittent Torque Bind -- is this probably a "Duty C" solenoid?", so let's start there. Duty solenoid "C" regulates engagement of the transfer clutch; that is, the "duty ratio" or on/off cycle timing, which in turn determines the degree of AWD. A failed "C" duty solenoid can cause the transfer clutch plates to be engaged full time, and drive to the rear wheels will be maximized. However, that in itself won't cause torque bind.

The transfer clutch plates are designed to slip, preventing torque bind. Those plates can get worn/contaminated, and on early 4EATs wear of a portion of the extension housing can also cause torque bind.

If placing a fuse in the under-hood holder eliminates the torque bind, duty solenoid "C" is likely fine. Furthermore, it indicates that you might be able to get rid of the problem by doing a full ATF fluid flush, or multiple changes. The fact that the six quarts of fluid you changed were "old, dirty" leads me to believe that getting rid of more might help (there's lots aside from what the pan holds). After flushing, or a series of 3 pan drain/refills, the problem may be resolved. If it's still there (or intermittent), try doing several tight figure-eights while in reverse gear (in a deserted parking lot or other safe place); that can help "scrub" the transfer clutch plates.

Some people have used limited-slip additive with good results, but I wouldn't start there. If none of the above resolves the problem, the extension housing and/or transfer clutch plates may have to be replaced.

#3 Gloyale

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Posted 10 July 2007 - 10:59 PM

A failed "C" duty solenoid can cause the transfer clutch plates to be engaged full time, and drive to the rear wheels will be maximized. However, that in itself won't cause torque bind.

The transfer clutch plates are designed to slip, preventing torque bind. Those plates can get worn/contaminated, and on early 4EATs wear of a portion of the extension housing can also cause torque bind.


This is not really true. A failed or disconnected Solenoid causes full line pressure to be sent to the transfer clutch. And while even then the plates will slip before an axle break, it still will cause massive torque bind(that's why some of us use a switch to disable the solenoid for a locked 4wd). So yeah, if the solenoid is failed(or somewhere else in that circuit, like poor contact at connector) you WILL get torque bind.

Place a fuse in the FWD slot under hood and see if it goes away. If so you have a TCU and a solenoid that are at least sometimes working properly. If the fuse doesn't stop the bind then I bet you're solenoid is bad. I would suggest a full trans flush refill with Type IIII synthetic trans fluid. either way/

#4 nipper

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Posted 10 July 2007 - 11:29 PM

CLASS!

You have forgotten the basics ...

Do you have all the tires properly inflated. Do all the tires match ....

Then move on from there. Without that no matter what you do it doesnt matter.

(now go flush your tranny).


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#5 OB99W

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Posted 11 July 2007 - 04:11 AM

This is not really true. A failed or disconnected Solenoid causes full line pressure to be sent to the transfer clutch.

Yes, which is why I said "A failed "C" duty solenoid can cause the transfer clutch plates to be engaged full time, and drive to the rear wheels will be maximized."


And while even then the plates will slip before an axle break, it still will cause massive torque bind(that's why some of us use a switch to disable the solenoid for a locked 4wd). So yeah, if the solenoid is failed(or somewhere else in that circuit, like poor contact at connector) you WILL get torque bind.

That's what I get for posting near midnight, which with my current schedule is way too late :) . I should have said "However, that in itself usually won't cause intermittent torque bind." (I'll admit that an intermittent connection, but not totally failed solenoid, could.)

I also failed to mention that the wear problem in the extension housing of some early 4EATs can be fixed with a steel sleeve. I should get to bed, or at least stop posting, earlier :) .

#6 OB99W

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Posted 11 July 2007 - 04:19 AM

[...]You have forgotten the basics ...[...]

Ooops, I can only plead sleep deprivation, as explained above. :o

To make up for that, I'll post a link:
http://www.endwrench.com/pdf/drivetrain/RearAxleBindingInfoF99.pdf

#7 Reveeen

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Posted 11 July 2007 - 07:57 AM

If it was me...............
I would check the connector, back of the engine, about center, heading to the transmission. Does your windshield leak? The reason I ask is if leaking on the driver's side top, all kind of nastyness can happen with the wires/wiring behind your dash, including, but not limited to the connector on the TCU, and the all important fuel pump relay.

#8 northgeorgiaroo

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Posted 11 July 2007 - 12:30 PM

Thanks all for the replies.

Tires all match, and I inflated them all to the owner's manual recommended 35 psi immediately after the drain/refill. That was part of why I was soooo hopeful that the problem was solved.

When the torque bind is happening, putting in the FWD fuse does not immediately solve the problem. The problem has been coming and going, so I can't really tell if putting in the FWD fuse eventually solved the problem, but my gut feeling is that if it were going to do the trick, it would be instant like "flicking a switch" -- am I right?

The fact that the power light flashes when I have the problem indicates to me that this is a component failure inside the transmission. I just thought I would confirm this with you guys before I borrowed a multimeter and crawled back under the car.

I have read the legacycentral post on diagnosing a Duty C problem, and I think I can manage it, but as someone who is frightened and bewildered by transmissions, any advice is appreciated.

I am going to lunch now, and I am stapling a note to my forehead not to forget to try and pull the code (with instructions from legacycentral) when I park. (Aside -- Does the tranny really have to be warmed up for this to work? If so, Why?

#9 northgeorgiaroo

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Posted 11 July 2007 - 12:34 PM

If it was me...............
Does your windshield leak? .


Windshield does not leak. All rubber seals are good, zero corrosion on body and frame (except the PO's fender bender that is causing some fender rust where it got smacked.).

That is why I still love this car, even though I have now swapped an engine and am now looking at opening the transmission back up.

#10 nipper

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Posted 11 July 2007 - 02:07 PM

Thanks all for the replies.

Tires all match, and I inflated them all to the owner's manual recommended 35 psi immediately after the drain/refill. That was part of why I was soooo hopeful that the problem was solved.

When the torque bind is happening, putting in the FWD fuse does not immediately solve the problem. The problem has been coming and going, so I can't really tell if putting in the FWD fuse eventually solved the problem, but my gut feeling is that if it were going to do the trick, it would be instant like "flicking a switch" -- am I right?

The fact that the power light flashes when I have the problem indicates to me that this is a component failure inside the transmission. I just thought I would confirm this with you guys before I borrowed a multimeter and crawled back under the car.

I have read the legacycentral post on diagnosing a Duty C problem, and I think I can manage it, but as someone who is frightened and bewildered by transmissions, any advice is appreciated.

I am going to lunch now, and I am stapling a note to my forehead not to forget to try and pull the code (with instructions from legacycentral) when I park. (Aside -- Does the tranny really have to be warmed up for this to work? If so, Why?


If you manage to pull the codes, ill bet you its telling you your Duty C is begining to fail. The new fluid prbbly helped to degum and lubricate the solenoid, but it is starting to go.
This is one of those things that you fix now, or end up buying a clutch pack along with the solenoid.


nipper

#11 grossgary

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Posted 11 July 2007 - 03:01 PM

there may be a pinout you can ground to flash the existing code from memory.

sometimes all of that code reading maneuvering...scratch head, put in gear, turn off, turn radio all the way up, remove headlight, start car, put in gear, then read the code....sometimes that's a diagnostic troubleshooting code and not the stored code. often you can just ground a pin-out for the existing trouble code which is far easier and works every time. i've never gotten the auto trans diagnostics to work either...can't recall if there's a pinout that you can ground though, that's how engines, ABS and other items work.

#12 northgeorgiaroo

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Posted 11 July 2007 - 04:39 PM

there may be a pinout you can ground to flash the existing code from memory.

sometimes all of that code reading maneuvering...scratch head, put in gear, turn off, turn radio all the way up, remove headlight, start car, put in gear, then read the code....sometimes that's a diagnostic troubleshooting code and not the stored code. often you can just ground a pin-out for the existing trouble code which is far easier and works every time. i've never gotten the auto trans diagnostics to work either...can't recall if there's a pinout that you can ground though, that's how engines, ABS and other items work.


Yep, tried three more times today, couldn't get the power light to flash any codes! Anyone got a way to read the TCU codes that doesn't involve pushing the manual button 6.5 times while cycling through the gears and touching your nose with your tongue?:confused:

#13 OB99W

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Posted 12 July 2007 - 12:33 AM

[...]
When the torque bind is happening, putting in the FWD fuse does not immediately solve the problem. The problem has been coming and going, so I can't really tell if putting in the FWD fuse eventually solved the problem, but my gut feeling is that if it were going to do the trick, it would be instant like "flicking a switch" -- am I right?

Yes, the expected ("normal") response would be pretty instantaneous.




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