AWD Binding

[TomsSVX]

Yeah... turning up a code 24 out of the teal. I tried plugging in the FWD fuse and to no avail. Nothing happens??:confused: Got a feeling it has to do with the chasis rather than the trans because I rebuilt the transfer clutches and solenoid C with parts known to be good but not new parts. This car has been having trouble with binding since before I got it. people like to just remove the rear half of driveshafts in order to "fix" their problems:rolleyes: Anyway, anyone have any ideas on where I should start looking before I go and buy a new solenoid C and tear the trans apart again??

Tom

[Tim]

My old tranny is cursed I tell ya! J/k


Bump for good luck :)

[TomsSVX]

well at least the AWD is working:rolleyes: Did u ever try to FWD fuse in ur car to see if it would do anything?? Just curios as to whether I am tracing wires in the car or the tranny??

Tom

[oab_au]

As it posts a code, it would have to be a wiring problem back to the C solenoid, the Solenoid itself, or the TCU.

If it was just the clutch plates binding it would not post the code.

Can't think of any thing else Tom.:(
Harvey.;)

[Tim]

Yea in my car once I put the FWD fuse in all the problems cease. This is the list of problems I had on my old tranny before my awd gave up completely:

1.Binding
2.A thunk/clunk when I came to a complete stop for like 10 seconds. It felt like I shifted into park when cold and shifted into drive.
3.a light thunk when gassing it, that's how I knew the rear engaged.

[Manarius]

Tom, are you binding on sharp/slow corners? This would make me lean much more towards the center diff. Over time, the 4EAT's will start to torquebind, and the source of this binding is the center diff (hence why when you put in the AWD fuse, nothing changes because the center diff is still powering the front wheels).

If you let this go, eventually you'll shear all the teeth from your center diff and you'll have a car that won't move.

[TomsSVX]

I will not drive the car like this. I still have my silver to drive, just trying to get my daily driver working. I know it has to do with the transfer clutches in the center diff, just trying to figure out what exactly is going on. I would just go buy a SOl. C and be done with it but the fact that my FWD fuse doesn't work makes me lean toward a different problem. I was wondering if anyone has had the same thing happen to them?

Tom

[intelisevil]

Try a bottle of limited slip differental additive in the transmission.

http://www.subaru-svx.net/forum/showthread.php?t=1980

It seems to have worked for me, no more binding in slow turns, transmission seems to shift the same as before. Now if I put the tranny in neutral when I'm just barely moving (foot off of brake) the car will actually continue to roll some. Prior to using the additive, the binding was bad enough that under the same conditions, the car would stop almost immediately . . . in neutral!

Previously, when I put the FWD fuse in, nothing happened, the light on the dashboard didn't even light up. I'll have to try it again, obviously just for short term testing . . . I've read what the long term results can be. :eek:

Still throwing a code 24, but this gives me more time to search for a WRX 5-speed etc.

Dan

[TomsSVX]

this is not my clutches sticking, it is the solenoid allowing full ATF pressure to the clutches. Once I can figure out why Sol. C is not working I have solved my problems. like I said, I don't "need" this car right now so I am not going to try temporary solutions, I just want it to work right

Tom

[Earthworm]

Do you have a spare TCU? That was Randy's problem a long time ago.

[TomsSVX]

I know I have a couple.... just need to find them.:rolleyes:

Tom

[THAWA]

Tom, are you binding on sharp/slow corners? This would make me lean much more towards the center diff. Over time, the 4EAT's will start to torquebind, and the source of this binding is the center diff (hence why when you put in the AWD fuse, nothing changes because the center diff is still powering the front wheels).

If you let this go, eventually you'll shear all the teeth from your center diff and you'll have a car that won't move.

How exactly do you shear teeth off of something that doesn't have teeth? The front and rear are connected through clutches, not gears.

Anyway, as was said, and you noted, it sounds like wiring. Probe some pins for resistance and voltage, an FSM would help greatly. Or just start throwing parts at it :)

[Trevor]

this is not my clutches sticking, it is the solenoid allowing full ATF pressure to the clutches. Once I can figure out why Sol. C is not working I have solved my problems. like I said, I don't "need" this car right now so I am not going to try temporary solutions, I just want it to work right

Tom

I am working from a Japanese manual showing the diff. type set up, but it would appear that the control arrangements are the same; i.e.fitting the fuse will fully activate solenoid C and the result is transmission locked front/rear. Therefore it would appear that your problem may be that, the solenoid is being continually energised (Specified as between 8 and14 volts) or is mechanically siezed open.

With the fuse in place, ignition on, engine stopped, selector in D and accelerator pedal fully released there should be 8 - 14 volts applied to the solenoid.

With the fuse out, Accelerator pedal fully depressed, then all as before, there should be no more than 0.5 volts.

Solenoid resistnce shoud be 9 - 15 ohms disconnected from the TCU.

Measuremants can be made at the TYCU between terminal - 3, (16 pin B68 connector) and ground.

I hope this information may enable you to ascertain if the TCU, solenoid or connecting wiring is electrically at fault, or the solenoid is mechanically faulty.

[Manarius]

How exactly do you shear teeth off of something that doesn't have teeth? The front and rear are connected through clutches, not gears.

Anyway, as was said, and you noted, it sounds like wiring. Probe some pins for resistance and voltage, an FSM would help greatly. Or just start throwing parts at it :)
Oh come on Thawa, you know as well as I do that when the AWD binds, 9 times out of 10 it's torquebind. Don't get smart with me. Torquebind isn't clutches sticking.

In the rear of the transmission is a watermelon sized aluminum housing that contains several valves, bushings and seals. The rear driveshaft that couples with the rear differential. The problem occurs in here, and the replacement of this cures it.

Inside of the housing the rear shaft spins and has teflon bushings and fluid seals for the AWD system. This is where much of the rear power is transferred. The problem occurs when these bushings wear against the aluminum. For some reason Subaru, or the transmission manufacturers, decided not to have a bearing or liner in lieu of using the housing itself as the wear surface.

This is where the problem and solution lies.

The bushings and seals wear the aluminum down after time. This allows the pressurized ATF to leak from one chamber to the next. The torque meant to be transferred to the rear ends up being greatly reduced and the fluid transaction causes the shuddering.
Source: http://legacycentral.org/library/torquebind.htm

[THAWA]

It's throwing a code, this is an electrical fault. There are no teeth that transfer power front to rear.

[Trevor]

It's throwing a code, this is an electrical fault. There are no teeth that transfer power front to rear.

The fact that it is "throwing a code", does not mean that the fault is restricted to an electrical problem. The manuals state that a code can indicate the seizure of a solenoid valve. This in spite of what may have been previously recorded here in the past. Refer my previous suggestions which you could follow.

[Manarius]

The fact that it is "throwing a code", does not mean that the fault is restricted to an electrical problem. The manuals state that a code can indicate the seizure of a solenoid valve. This in spite of what may have been previously recorded here in the past. Refer my previous suggestions which you could follow.
Solenoid seizures don't usually cause binding. And when they fail, most often it's C and that means you'll have slow AWD response. That's why Thawa thinks it's electrical.

[TomsSVX]

I know what manarus is talking about but That is not the issue. Thanks trevor for the info, this tell me that when the Sol C is lacking power, it will be stuck in the full open position and will keep it FWD. now that I know that, there are 2 real world posibilities. One, the wires are pinches somewhere and this is not allowing the solnoid to close and release the rear wheels. OR the solenoid is fried and it is stuck open. SO, all I need is a pinout for the sol C wire outside of the trans that I can ge a voltage reading from. If there is power on the outside of the case, I will have to operate anyway. If not, I do not have to waste 7 qt's of good atf and I need to find out where my electric failure is happening. I will take a look at my service cd's and see what I can find with the wiring. Anyone with access to these files and has the ability to post them... please do

Tom

[Trevor]

I know what manarus is talking about but That is not the issue. Thanks trevor for the info, this tell me that when the Sol C is lacking power, it will be stuck in the full open position and will keep it FWD. now that I know that, there are 2 real world posibilities. One, the wires are pinches somewhere and this is not allowing the solnoid to close and release the rear wheels. OR the solenoid is fried and it is stuck open. SO, all I need is a pinout for the sol C wire outside of the trans that I can ge a voltage reading from. If there is power on the outside of the case, I will have to operate anyway. If not, I do not have to waste 7 qt's of good atf and I need to find out where my electric failure is happening. I will take a look at my service cd's and see what I can find with the wiring. Anyone with access to these files and has the ability to post them... please do

Tom

As I advised earlier in the thread, you should make your measurements at pin 3 of the TCU sixteen pin block, B68, which is 3rd in from left on the top row, looking inwards, key at the top. The connecting wire is shown as grey in colour (color).

The lock up fuse completes a circuit to ground from terminal 2, 20 pin connector B66. ( 2nd top row)

[TomsSVX]

ok thnx i will look into it when i have time when i am at home

Tom

[TomsSVX]

Trevor, need some advice. I am actually starting to get back into this car now that Reading is over. I was downstairs for a few minutes before taking a look at things. I found the #3 connector in B68 and did a quick test. Seems that when the ignition is on, FWD fuse in place, and acc pedal completely released(closed throttle) I have power enough to light my test light(12v). When I press the acc pedal any amount the power drops(light turns off). Now This is what I expected but what I didn't expect is that the power does not return upon release of the pedal. I know I need to get under there with my multi-meter but I didn't have any light to work with tonight.

Another thing. When I was trying to see if it was binding before the acc pedal was pushed I had a strange occurance. The FWD light on the dash was lit for a couple seconds, 3 at most. It quickly shut off and did not come back on after repeating the same steps.

This all makes me wonder if it could be TPS related. If I press the acc pedal the TPS voltage should change appropriately. Now if when I release the pedal the voltage does not return to .5v at idle it would still read at as using the throttle and not allowing the Solenoid to close(also causing power at pin #3 not to come back). It is a long shot and just a comment I felt necessary to make. I will look further into it tomorrow. I should also have time tomorrow to get a multimeter on pin 3 and get some more readings. Please respond to this and tell me what you think. I am almost ready to make a trip to Harry' U-Pull it for a cheapo legacy/imprezza 5 speed and get rid of the slush-box, but I would rather keep this auto. Thanks for your help and input

Tom

[Trevor]

Stick with it Tom,

The TPS does not directly control the solenoid as you no doubt realise, but does so via the TCU, so that you should check it carefully so as to rule it out of the equation. Refer the simple method I wrote up for the “how to” section. Measure the voltage by sticking a needle or pin through the wire as I suggest.

You may think this overkill, but this is good advice. Make notes as you go along, writing down each test or check you make. I know how confused one can become ( I always fall into this trap.) with this sort of issue and it is not easy to be sure what has and has not been checked, as the path gets long and involved. Especially when the project has to be attacked in dribs and drabs.

Your test light measurement will be spot on and has a distinct advantages as resistance in the circuit is likely to show, when it would not using a sensitive meter. Have no concern in this regard.

It is quite possible that the voltage at pin 3 does not return after closing the throttle due to the TCU “holding the instruction”, if you get my meaning. After releasing the accelerator, turn the ignition of and on again, without touching the accelerator, see if the voltage returns. If it does, I think you can assume all is as it should be and what I suggest applies. If not, you could be onto something.

The FWD drive light is another issue. I have a problem in that the manuals I have cover the non US set up, whereby the fuse locks the front and rear for AWD, rather than disconnects the rear drive, but it would seem that the solenoid control is the same. It would appear that this indicator light is directly on the FWD control circuit which could mean that this circuit became live from the fuse end, or alternatively through a back feed from the TCU. Did you by any chance have the fuse left in the holder and nearly connecting ? If nothing is untoward on that side, you must get back to suspecting the TCU.

Don’t get frustrated, get mad, put your teeth into it and try to make the challenge fun. However proceed logically and not like a bull at a gate like some !! The answer is there and you have the brains to find it.

All the very best, Trevor *<)

[TomsSVX]

Stick with it Tom,

The TPS does not directly control the solenoid as you no doubt realise, but does so via the TCU, so that you should check it carefully so as to rule it out of the equation. Refer the simple method I wrote up for the “how to” section. Measure the voltage by sticking a needle or pin through the wire as I suggest.

You may think this overkill, but this is good advice. Make notes as you go along, writing down each test or check you make. I know how confused one can become ( I always fall into this trap.) with this sort of issue and it is not easy to be sure what has and has not been checked, as the path gets long and involved. Especially when the project has to be attacked in dribs and drabs.

Your test light measurement will be spot on and has a distinct advantages as resistance in the circuit is likely to show, when it would not using a sensitive meter. Have no concern in this regard.

It is quite possible that the voltage at pin 3 does not return after closing the throttle due to the TCU “holding the instruction”, if you get my meaning. After releasing the accelerator, turn the ignition of and on again, without touching the accelerator, see if the voltage returns. If it does, I think you can assume all is as it should be and what I suggest applies. If not, you could be onto something.

The FWD drive light is another issue. I have a problem in that the manuals I have cover the non US set up, whereby the fuse locks the front and rear for AWD, rather than disconnects the rear drive, but it would seem that the solenoid control is the same. It would appear that this indicator light is directly on the FWD control circuit which could mean that this circuit became live from the fuse end, or alternatively through a back feed from the TCU. Did you by any chance have the fuse left in the holder and nearly connecting ? If nothing is untoward on that side, you must get back to suspecting the TCU.

Don’t get frustrated, get mad, put your teeth into it and try to make the challenge fun. However proceed logically and not like a bull at a gate like some !! The answer is there and you have the brains to find it.

All the very best, Trevor *<)

A few things. When I turn the key off and back on, the voltage returns to pin 3 no problem. In the US models the fuse grounds the cicuit and by this should be feeding a constant 12.v signal to the sol. in order to keep it strictly FWD. My concern is that it is not completing this circuit somewhere down the line between the fusebox and the TCU. I have replaced the TCU with another and nothing has changed. I figured this the easiest step and I would do this first. I do have a lead comming off the white(middle) wire of the TPS to test voltage without it grounding when I do not want it to. I am really leaning toward this being an issue as the idle is sometimes a little funky. But the only disheartening thing is, once I "blip" the throttle the idle will settle to where it should be and does not change. But when I do this, it is still binding. I would really like to get in it with a Select Monitor so I can see the volatages while I am driving or testing instead of being burried under the dash and hitting the gas and brake wit my elbows:rolleyes: I will give you more information as I get it but for now this is all I know. There are too many things not doing what they should for it to be sol. C alone but it still very well could be so I am not ruling out that option as of yet.

Tom

[TomsSVX]

Took some more measurements today. At pin #3 I have the following voltages

Key on engine off
Closed throttle- 11.25v
WOT- .15 volts

Engine on
Closed throttle- 13.3 volts
Quick run to WOT in park- .35 volts(at least i think thats what I saw)

I double checked the TPS and it is showing .5v at idle and it does increase along with throttle movement. I have a feeling more and more that it is the actualy solenoid itself. Later I may have time to get under it and measure voltage off of the sol. C wire entering the transmission to see if I am losing it in the harness somewhere. If not I will split the ass end of the case open and check volatge at the solenoid itself. I may just have to buy a new solenoid but I want to be sure first.

Tom

[nipper]

I'm sort of an expert on torque bind on the other soobie board. i just posted this to another thread i hope this help. The autos dont have a center differnetial, the manuals have one, in conjunction with a viscous coupling.

http://www.subaru-svx.net/forum/showthread.php?t=32960

i have a beutiful description from subaru on how the 4eat transmission works if anyone wants it.

nipper

[oab_au]

Tom I think it there is confusion on the C solenoid. The one on the US model is different to the VTD model. I have written about it before some where. The one in yours, turns FWD, when on full signal. With no signal, the transfer clutch is full on.

The VTD is the opposite, no pressure with no signal, full pressure with full signal. The difference is in the C solenoid, the US one is normally closed. The one in the VTD is normally open. I guess that this was to allow the units to "fail safe" differently.:D Yours defaults to 50/50, ours to no Limited Slip Clutch.

This the VTD unit, but your hydraulics are the same.
http://www.subaru-svx.net/photos/files/oab_au/34536.jpg
You can see that the C solenoid bleeds off The yellow pilot pressure, to reduce the pressure on the transfer spool valve so that the spring can move it across to turn the RED line pressure off the transfer clutch.

For it to bind, either the transfer valve has to stick in the on position, or the C solenoid is not fully bleeding off the pilot pressure, to hold the transfer valve on.

It your case I think it is the C solenoid that is not opening fully. Maybe it has a mechanical problem to prevent full armature travel, or there is some foreign body stuck in it preventing full travel. There is also a chance that the duty cycle signal is reduced by a resistance somewhere, though I don't know if the TCU could detect that, to post a code.

Harvey.;)

[TomsSVX]

Ok so this confirms my suspicion that when the solenoid does not have an ~12v signal the transfer clutces are fully engaged. In this case I know what I am looking for. Thank you guys and I will keep you updated as I have time to work on it

Tom

[THAWA]

The fact that it is "throwing a code", does not mean that the fault is restricted to an electrical problem. The manuals state that a code can indicate the seizure of a solenoid valve. This in spite of what may have been previously recorded here in the past. Refer my previous suggestions which you could follow.
I view a failed solenoid as an electrical fault, but I see how you could think of it as a mechanical fault. Mechanical fault to me means more like clutches stuck or worn, or broken drum or something. It's just different thinking.

[Trevor]

I view a failed solenoid as an electrical fault, but I see how you could think of it as a mechanical fault. Mechanical fault to me means more like clutches stuck or worn, or broken drum or something. It's just different thinking.

OK but nothing to do with clutches atc. The solenoid valve, the item referred to, can fail in a mechanical or electrical sense, i.e. (1) The armature or valve could be mechanically seized/stuck, open or closed. (2) The solenoid coil could be electrically shorted or open circuit, either fault thus effecting the hydraulic circuit.

[TomsSVX]

Ok, finally got it up in the air tonight and did aquickl test. Turns out that my sol. C is working and it is working properly. With the ignition on/engine off, when I hit the throttle, I can hear the sol. cycling. As I open the throttle, the solenoid cycles less and less until it doesn't cycle anymore at/close to WOT. So, Why the hell am I having a binding issue and why is the Sol C code comming up?

Tom

[Trevor]

Ok, finally got it up in the air tonight and did aquickl test. Turns out that my sol. C is working and it is working properly. With the ignition on/engine off, when I hit the throttle, I can hear the sol. cycling. As I open the throttle, the solenoid cycles less and less until it doesn't cycle anymore at/close to WOT. So, Why the hell am I having a binding issue and why is the Sol C code comming up?

Tom

Reference your message in another thread. I do not hide behind an alias and am pleased to provide my phone number and address. Trevor R. Sheffield, 16A Seaside Avenue, Waterview, Auckland, 1007, New Zealand. (nz) 09-8208553

However please hold off phoning until I have had time to mull over your dilemma and I will come back here, or by PM. Meantime my thought is that the valve could have something preventing full travel, e.g. on the seat, but could still be moving enough to be audible. What do you think ?

[TomsSVX]

its a good possibility that is the case but it still boggles my mind. The battery in the car is dead right now because I don't have the time or spare cash to throw at this car right now. I will get a jump pack tomorrow and jump it again and see if it is possibly fixed. I was fiddling around with the harness before I did the test so maybe I cleared up a bad connection i don't know

Tom

Edit: Damn, you are in New Zealand, sorry man but those charges would kill my phone bill, thanks though

[TomsSVX]

Well, thanks to SVXfiles, I have installed a whole new tailshaft. The FWD lights comes on now. I have yet to take it down off the jackstands but it is family time now. I will take it for a spin tomorrow or later on tonight when I take it down

Tom

[TomsSVX]

It's ALIVE!!!! The new tailshaft has fixed all ailments. My guess is that there was an abstruction of the transfer valve in the old housing which would not allow it to actually cut the line pressure. I know the Sol. C was working but the transfer valve was not. So all in all it was a good day:D Now I need to go get it registered and try to get it passed by the inspection o Joisey. Anyway, thank you all who helped, this car is now running well and I am very grateful since I amy decide to blow up my silver one soon:D :D

Tom

[huck369]

Oh come on Thawa, you know as well as I do that when the AWD binds, 9 times out of 10 it's torquebind. Don't get smart with me. Torquebind isn't clutches sticking.


Source: http://legacycentral.org/library/torquebind.htm



I'm with Thawa, the 4EAT doesn't have a "Center Diff" just a clutch pack that feeds power to the rear diff, directly split off the main shaft.

[oab_au]

Tom, are you binding on sharp/slow corners? This would make me lean much more towards the center diff. Over time, the 4EAT's will start to torquebind, and the source of this binding is the center diff (hence why when you put in the AWD fuse, nothing changes because the center diff is still powering the front wheels).

If you let this go, eventually you'll shear all the teeth from your center diff and you'll have a car that won't move.

I liked this one better Huck, we have a center diff with teeth, and a AWD fuse.:D

Harvey.;)

[intelisevil]

I liked this one better Huck, we have a center diff with teeth, and a AWD fuse.:D

Harvey.;)
Be nice . . . Some of us are still learning! :o

Dan

[TomsSVX]

actually he is probobly refering to the stage 2 4eat in the more current Subies. Don't trash what you don't know

Tom

[Trevor]

Be nice . . . Some of us are still learning! :o

Dan

Courtesy applauded. All usually learn from their mstakes. However it is confirmed that there are the odd ones out.