Rear wheels do not work. why?

juice91si · Post by **juice91si** » Wed Nov 12, 2008 8:09 am

ok, so now that i have my motor up and running good, i'd really like to get the awd working so i can have some real fun in the winter.

here we go.

it's a 4eat. when i put the motor in, my bro and i replaced the duty c with a good working unit, i also changed the clutch packs with a lower km donor car which was in working condition. the tranny was taken apart and received a partial rebuild with the help of a donor turbo tranny.

i have read that if there is a clog in the line somewhere, the awd wont work. i have a spare extension housing and the valve body that the duty c bolts to, is this the area that may be prone to clogging?

what steps do i take to find the actual problem? i'm kind of lost as to what to do.

juice91si · Post by **juice91si** » Wed Nov 12, 2008 8:25 pm

i reset the tcu, and it does act differently, but still no awd.

on the bright side (maybe) my power light came on when i mashed it, and turned back off, i read this is normal.

i am pretty sure the clutchpacks are not burnt, the tranny i got was in very good condition. the duty solenoid again, was tested and from every observable point it was functioning.

i called my transmission guy and he is going to help me diagnose the problem too because searching for the solution on forums is not yielding results with difinitive answers.

i'll have to tackle this myself it appears.

i am gearing up to drop the extension housing off again, and replace it with my other tail housing with new gaskets btwn the duty c valve body, and plate/housing.

as soon as i figure out which wires to get a reading from ill test various components of the awd control system.

ericem · Post by **ericem** » Wed Nov 12, 2008 9:06 pm

Try changing the fluid a few times. Just check the fluid and see if it is overfilled to begin with actually. Another thing is if you mash the pedal or just tap on it fast whatever you will get the powerlight to turn on, and it will make it go 50/50 split. So see if it engages with the light on. With my awd system I have a problem where there is no awd until it is warmed up.

juice91si · Post by **juice91si** » Wed Nov 12, 2008 9:15 pm

the fluid has been changed 4 times.

while mashing, the power light was on, and i was spinning one of four tires. twas fully warm too.

where the hell is the TCU??

juice91si · Post by **juice91si** » Thu Nov 13, 2008 1:15 am

found the tcu and tested the duty c soledoid curcuit with and without the fwd fuse. it is good.

next i will have to test the wiring harness for power and continuity. and eventually the solenoid itself.

i may do a line pressure test if the wiring stuff checks out fine.

ericem · Post by **ericem** » Fri Nov 14, 2008 3:39 am

I have never seen the solenoid out or the solenoid in person for fact. But does it need to be aligned in a specific way in order for it to operate correctly?

juice91si · Post by **juice91si** » Fri Nov 14, 2008 6:44 am

no, theres only one way it goes on.

the way i figure theres only a few possibilities.

its either mechanical, or electrical.

if electrical, the problem lies in the wiring between the tcu and solenoid/sensors, or a failed/failing solenoid/sensor.

if mechanical, it would be either a clutch pack issue (which at this point i highly doubt, but ya never know) or a fluid pressure issue.

if its the clutch packs, ill replace em. if the tail section is not getting enough pressure, that issue will may be more intensive. i believe pressure comes directly from the pump, and as per my tranny guy, if there isnt enough pressure, the car wouldnt even move, he has a hunch its electrical.

anyone know if, say, the front or rear speed sensor was giving a different reading, the tcu or power light would tell me, or would it just disable the rear wheels?

juice91si · Post by **juice91si** » Tue Nov 18, 2008 5:16 am

i am beginning to thnk a piston in the duty c valve body is stuck or a passage is clogged. i am going to use the spare extension housing and valve body from my donor 4eat which i know is clean and clogless. if it doesnt work ill look a little more in depth.

its gotta be as problem located in the extension housing unless pressure is not coming from the front pump...or something electrical..fuck i just want my awd working...

anyway, to the best of my knowlwdge this is how the awd system works.

ultrasonic · Post by **ultrasonic** » Tue Nov 18, 2008 8:57 am

Make sure there is not a fuse in the FWD socket under the hood.

juice91si · Post by **juice91si** » Wed Nov 19, 2008 2:01 am

i hate when people say that. you really think that with all i have done i wouldnt have checked that?

nothing personal but everytime i see a thread like this someone asks that.

ultrasonic · Post by **ultrasonic** » Wed Nov 19, 2008 2:21 am

juice91si wrote:i hate when people say that. you really think that with all i have done i wouldnt have checked that?

nothing personal but everytime i see a thread like this someone asks that.

Hey, no problem. I'm sure you've checked everything except what ever is causing the issue. Stupid of me not to realize that you are smarter than most other folks in the internet. Sorry to have wasted your 2.5 seconds that it took to read my post.

I hate when people ask for help in a public forum and then are not gracious enough to politely filter through the responses. I think you're rude.

Nothing personal.

kleinkid · Post by **kleinkid** » Wed Nov 19, 2008 4:07 am

When we are hungry or tired, we are sometimes more emotional. Do you f'en understand that!

juice91si · Post by **juice91si** » Wed Nov 19, 2008 9:10 am

i AM rude.

i_c_the_light · Post by **i_c_the_light** » Wed Nov 19, 2008 10:45 pm

OMG HAV J00 CH3CKED DA FEEEUUUUUZEEEEE!!!111!!11!!

THEY'VE CUT THE HARDLINE, IT'S A TRAP!!

Arctic Assassian · Post by **Arctic Assassian** » Thu Nov 20, 2008 2:25 am

And all you fuckers wonder why all the people that ACTUALLY know thing aren't here anymore... I'm out again.

kleinkid · Post by **kleinkid** » Thu Nov 20, 2008 3:09 am

Artic a.--go inside and warm your knickers up, its all in fun.

And, don't stay away too long, you always have something titulating to say!

RJ93SS · Post by **RJ93SS** » Tue Jan 20, 2009 7:12 am

what was the problem with the awd, any results?

juice91si · Post by **juice91si** » Wed Jan 21, 2009 7:06 pm

lots of things going on right now. havent had a chance to crack open the tranny yet

log1call · Post by **log1call** » Thu Jan 22, 2009 2:39 am

The problem will be inside the tranny. The clutch pack gets full line pressure and if it isn't getting it nor is the rest of the trans as far as I know about the hydraulic circuits. I have overhauled a couple of these boxes by the way. The solenoid valve lets clutch pressure bleed away so the clutch can slip momentarily so as to prevent binding between the front and rear. If the solenoid is not working for any reason, either a blockage or not getting power to it, the clutch will be locked up and you will have the well documented problem when turning sharply. That only really leaves the clutch is worn out or assembled incorrectly, diff is buggered, or there is no pressure getting to the clutch. As far as I know there is only one likely place where the hydraulic pressure could be blocked and that is a little pilot pressure filter that is in the body of the trans in behind the solenoid's steel housing in your picture. If that filter gets blocked though it would give you clutch bind anyway, so that seems to be an unlikely cause. The official word from the manual says... "Disconnect the Transfer Duty Solenoid Connector and remove the bolts that secure the
Duty Solenoid and Transfer Control Valve to the Transmission Case. Remove the small
filter from the cavity in the Transmission case at this time. Remove the Parking Pawl, spring
and Parking Pawl Shaft." And.... "The Transfer Duty Solenoid controls the amount of pilot pressure supplied to the backside of
the Transfer Control Valve Piston. If the duty ratio signal from the Transmission Control Unit
(TCU) is small the Transfer Duty Solenoid stays off more than it is on and drains less of the
pilot pressure. This will result in an upward movement of the control valve increasing the
amount of line pressure to the Transfer Clutch. An increase in the duty ratio turns the solenoid
on more than it is off and drains more of the pilot pressure. The Transfer Control Valve moves
downward restricting the amount of line pressure to the Transfer Clutch."

Hope that helps.

If someone can tell me how to insert a picture in here I can post a circuit diagram of the hydraulic circuit.

juice91si · Post by **juice91si** » Thu Jan 22, 2009 3:45 am

to insert a pic, you have to find a site to host your picture.

www.photobucket.com is good, just sign up for free.

upload a pic by browsing your hard drive and selecting it. copy the textbox that has [IMG] at the front, then paste it in your reply.

juice91si · Post by **juice91si** » Thu Jan 22, 2009 4:07 am

An increase in pressure results in the activation of AWD. Just so we're on the same page here. Agree?

Then, if no pressure at all, no AWD at all. Agree?

So, if there is a blockage between the inital line pressure port, and the end orifice that shoots fluid at the mpt, then no AWD.

Can you post whatever scans you have?

log1call · Post by **log1call** » Thu Jan 22, 2009 8:18 am

Yes hydraulic pressure puts the clutches on. It is not an increase in pressure that put it into AWD though. The pressure is always there and it forces the clutches to lock up, then to make them slip a tiny amount they pulse a solenoid that dumps pressure out of the clutch pack. If the solenoid, TCU, or wiring play up electricaly, it defaults to full pressure and 100% 4WD. The pressure puitting the clutch on is called line pressure and it is what operates all of the tran clutches. It is fed through 8mm pipes. If it fails the whole works stop. About the only thing in the hydraulics that would cause it would be the solenoid being stuck open or a seal gone in the clutch pack or shaft feeding the oil to the clutch.

What's MPT?

I'll post a couple of PDFs the early model is yours but the pictures and descriptions are better in the later model trans manual. For what you are looking at they are both the same.

log1call · Post by **log1call** » Thu Jan 22, 2009 8:35 am

Ok, if you go here... http://cid-4ca3c3459aaa7f7f.skydrive.li ... ublic?uc=3 you can download a manual. Your car is the 4eat and the other one is 4eat-ii.

juice91si · Post by **juice91si** » Fri Jan 23, 2009 8:36 pm

how would the clutches slipping make awd turn on?

its when they lock, that awd is activated. an increase in pressure makes awd happen. even with the links that you just posted, seem to indicate that.

and MPT is multi plate transfer clutch, which are the clutches you are referring to...which is what subaru calls them...including the links you just posted...

log1call · Post by **log1call** » Sat Jan 24, 2009 12:29 am

I think we must have a missunderstanding.

I didn't mean that the clutches slipping make awd occur. Slipping clutches will stop awd occuring.

They apply line pressure to the clutch pack all the time and at full pressure. To allow the car to turn sharply they momentarily release the clutches. They release the clutches by draining some of the pressure away. They do this continuously and it is accomplished by switching the solenoid on and off hundreds of times per minute. The computer controls that.
If the ecu, wiring or the solenoid play up, the clutches get applied full on and you have trouble doing sharp turns.

To get no drive you must have either worn clutches or, leaky seals allowing the fluid pressure to leak away faster than it can get through the restrictor in the valve that feeds the pressure in there .

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Rear wheels do not work. why?

Rear wheels do not work. why?