The never ending AWD problem!

Okay, I am not a complete novice at this SVX thing, I have had an SVX since '92 but none more baffling than this one. I have had a continous problem getting the AWD drive to work. I have had five trannies in the last year and a half, as well as I have had the entire car overhauled and spent almost 15,000 dollars fixing this specimen and have been without the car for a year now. THe guy that finally woked on the car has done a great job (though slow).

BUT!!!, the AWD drive does not work still. I have replaced not only the tranny at Subaru dealership here but the duty solenoid c and the clutch pack twice and still there is no AWD. I know that the gentleman that is working on the car has gotten over his head now and decided to give me an excuse:
"I have called Japan and was delighted to speak to the engineers (I guess they speak english?) and explained your problem. They have said that there is nothing else I can fix on the car and it is performing to specs at this time. The TCU on this car has learning capabilites and will learn to thrust power to the rear wheels as you continue to drive the vehicle"

WHAT? No that is not true? I know that the TCU does have learing capabilites but that is simply shift points and general transmission functions not anything to do with the AWD system. The AWD system is direcly linked to the ABS system which should, if working properly, identify slip and move power through coupling or clutch packs diverting power left to right using limited slip diff?????? There is no learing to be done????

Am I close? Is this guy blowing me off or receiving bad information from Subaru?

Any thought on how to get my AWD back? I have paid everyone to try to fix the car???


g

P.S. I am ready to sell her off, I have had it with this car!! WHo wants to buy?

[Mr. Pockets]

Please start over and explain the symptoms. You say your 'AWD doesn't work,' but what do you mean by that? Is it binding? Are the rear wheels not being driven at all? If that's the case, how do you know?

Okay here are the sympoms, the front wheels WILL break on wet pavment. If starting in manual and the gear selector is in thrid or second the car will barely move (as is is supposed to not take off abruptly) and I can smell a burning type smell...
The drive line seems to shake at times and make the car feel like there are out of balance tires this shake will go away depending on the pressure that is put on the pedal. light pedal=no shake, moderate=almost unnoticable shake, heavy pedal=shake like tire out of balance. The shake does not go away if you just let the gas off quickly it will last sometimes... There is no binding at all in this car. Need any more info?

g

[Earthworm]

Has the TCU been replaced?

Have you considered a 5spd?

Why would I consider a replacement for a TCU?

Not a five speed but a six speed has been considered, just in a new car not that one!

[Earthworm]

Originally posted by greg
Why would I consider a replacement for a TCU?

It seems that everything else has been replaced except the TCU. Are there any 5spd SVX's nearby with spare TCU's you could test?

I prefer not to be throwing parts at the SVX just because it hasn't been replaced. If there was a valid reason that the TCU might need to be replaced I would contemplate it but at this time I would be more apt to replace all the ABS sesors than the TCU since the tranny is shifting superbly...?

[lee]

Greg,

Ask your tranny guy which of the following things have been checked for function (all of them can affect AWD operation):

TCU (Someone with a spare unit might lend you one if you report out the other problems have been eliminated)
Front vehicle speed sensor (should throw a code, do you having the blinking power light)
FWD switch (is the fuse in or the line shorted)
Throttle position sensor (not sure how much it will impact - there has been a recent thread about the dropping resistor - that would also throw a blinking power light)
ATF temperature sensor (if you get high gear and torque converter lock-up this isn't a likely cause)
Control valve (was it cleaned & checked when it was rebuilt)
Transfer clutch (assume it was a part of the rebuild)
Transfer valve
Transfer pipe (a line pressure test at the fitting on the extension housing would show if this or the valve was a problem)
Duty solenoid C (should have been replaced in the rebuild)

[Mr. Pockets]

Originally posted by greg
I prefer not to be throwing parts at the SVX just because it hasn't been replaced. If there was a valid reason that the TCU might need to be replaced I would contemplate it but at this time I would be more apt to replace all the ABS sesors than the TCU since the tranny is shifting superbly...?

Why would you replace the ABS sensors? They have nothing to do with the transmission - the TCU does. The car may be shifting beautifully, but the transfer clutch is part of the transmission and therefore controlled by the TCU.

Like others here, I suspect the part you haven't replaced five times. That or its wiring.

thanks guys for the suggestions I think that I will give a try to the TCU. I guess your right if everything else has been done the clutch pack pressure has been tested and all other transmission functions seem normal! Thanks

G

[Earthworm]

Have you had a chance to try changing the TCU?

[lee]

if you don't have access to a TCU to try, you might run these tests on the existing system - all you need is a VOM & some time. Let me know if you need a diagram or something to interpret the connectors & terminals.

1) CHECK SIGNAL VOLTAGE OUTPUT EMITTED FROM TCU.
a. Install spare fuse on FWD connector and set in FWD mode.
b. Turn ignition switch ON (with engine OFF).
c. Move selector lever to "D".
d. Measure voltage output emitted from TCU (with accelerator pedal released).
(Connector) & Terminal(s) Specified value
(B68) No.3 - No. 10 8-14V
e. Turn ignition switch OFF.
f. Remove spare fuse from FWD switch.
g. Turn ignition switch ON (with engine OFF).
h. Move selector lever to "D."
i. Measure voltage output emitted from TCU (with accelerator pedal fully depressed).
(Connector) & Terminal(s) Specified value
(B68) No. 3 - No. 10 0.5 V (max)

If this is OK, then the TCU is sending the appropriate signal...now to see if it's getting received properly by the transmission.

2) CHECK HARNESS BETWEEN TCU AND DUTY SOLENOID C.
a. Disconnect connector from TCU.
b. Disconnect connector from transmission.
c. Measure resistance between TCU connector and transmission connector.
(Connector) & Terminal(s) Specified value
(B68) No. 3 - (B14) No. 11 0 ohm
(B68) No. 3 - Body 1 M-ohm min.
(B68) No. 10 - (B14) No. 4 0 ohm
(B68) No. 10 - Body 1 M-ohm min.
3) CHECK DUTY SOLENOID C'S GROUND LINE.
a. Disconnect connector from transmission.
b. Measure resistance between transmission connector receptacle and transmission case.
(Connector) & Terminal(s) Specified value
(T2) No. 4 - Transmission 1 ohm max.
4) CHECK DUTY SOLENOID C.
a. Disconnect connector from transmission.
b. Measure resistance between transmission connector receptacle's terminals.
(Connector) & Terminal(s) Specified value
(T2) No. 11 - No.4 9-15 ohm

turns ou there needed to be a new set of seals in the clutches the originals were too low and were not making a seal, the TCU was bad and needed to be replaced the drive shaft U-joint is being replaced and hopefully when I get it back it might be fixed, I am loosing faith quickly and by the thousands of dollars!

thanks for all the input guys!

-G