AT lost 1st. and 4th.

[Ivan]

Hi there.
I've been ghosting this site for quite some time now and let me start by saying thanks for all the great help and ideas that You all are posting

But now it is my turn to have a major problem, - i think ...

After driving normaly for about two hours on the highway i got in to a small town and suddenly it felt like the car had no power at all.
It turns out that my AT stays in 2nd. and 3rd. gear at all time. 1st. and 4th. is gone.
If I try to start with the selector in 1st. the car dont move att all.
If I start slowly in 2nd and then select 1st. the car breakes to a stop.
Reverse is OK and there is no difference if the manual switch is on or off.

The fluid levels are at normal and there is no current codes on the TCU.
(On previous codes I get 32 and 33 - VSS1 and VSS2)

Anybody ave any ideas as to what has happened ?
Am i looking at a replacement or can it be fixed ?

All the fluids where changed just 3 months ago and the car has about 200KKm (~125KMiles) on it.

[free5ty1e]

Are the vehicle speed sensors used for the auto transmission to know what set of gears to lock? That's a strange problem...

[Bheinen74]

check both sides and make certain the electrical connectors are connected tightly for the tranny wiring. They could be a little loose, but still seem connected. make certain they are snapped together tightly.

[Ivan]

I checked both connectors an they seems ok, but anyway I disconnected both and checked the inside too, and they looks like new, no sign of bad connections...
I also reset the TCU by taking the fuse out for about 20 min.

And I still have the problem

[Tleg93]

I don't think the speed sensor has anything to do with how the car shifts. I've driven with my speed sensor disconnected and the car still shifted, it ran like crap, but it shifted. From what I know (and I could be wrong) the shifting is done by internal planetary gearset inside the tranny. I dug up a really neat article on howstuffworks.com that shows it. It's pretty cool and it's a good learning resource.

http://auto.howstuffworks.com/automatic ... ssion1.htm

There's like eight or nine pages with cool animations you can play with. It's not going to solve your trouble but it may help.

[Warp3]

The first thing that comes to mind that 1st gear and 4th gear have in common is what I saw when reading the TCU pinout that I found posted on the forums here. It shows that both 1st and 4th gear involve 12V (10-14V to be precise) on pin 14 of connector B33 which is listed as "Shift Solenoid 1" (2nd and 3rd are listed as <1V on that same pin).

Now unless I'm misreading that or misunderstanding how the 4EAT works, my first thought is that Shift Solenoid 1 is dead or the wire that connects it to the TCU is disconnected.

[Tleg93]

That's sure interesting. I wouldn't have thought that the tranny relied on a solenoid to shift into two gears out of four. I don't see the reason why that would be. Where is the solenoid?

[Warp3]

That's sure interesting. I wouldn't have thought that the tranny relied on a solenoid to shift into two gears out of four. I don't see the reason why that would be. Where is the solenoid?

No clue where the "shift solenoids" are, I was just going based on the info I gathered from the TCU pinout which says that "Shift Solenoid 1" should read 10-14V when the shifter is in 1st or 4th and <1V when in 2nd or 3rd. FYI: There is also a "Shift Solenoid 2" that reads 10-14V when the shifter is in 1st or 2nd and <1V when in 3rd or 4th and a "Shift Solenoid 3" that does the same for Drive (10-14V) and Neutral (<1V).

For all I know it may not even be the problem, but "Shift Solenoid 1" does match up to the 2 gears that aren't working, so I figured it was at least worth a shot to mention.

[Legacy777]

shift solenoids are in the valve body, which is in the transmission.

[Ivan]

I just talked to a local Tranny Guru and he is also thinking that it might be an elektrical problem.
Exept that he don't like that it is breaking when 1st. is selected...
Also he says that if any wires where broken, it would be seen as an error code on the TCU.

I'm going to check the voltage levels on the TCU terminals tonight and if they look ok, I have to take a look inside the tranny. It should be possible to access the solenoids from the bottom when the pan is out.

[Ivan]

Finally I got around to check the TCU levels and both the inputs and the outputs seems to be whitin specs. I also tried disconnecting the solonoids and the sensors one at the time to see if the TCU would report an error, and it did...

After analyzing and reading a bit I now understand that it is actually only 3rd gear and reverse that works, - not 2nd and 3rd as I wrote earlyer. It seems that the tranny is in fail-safe (limp) mode, and what I thought was a shift between 2nd and 3rd, is actually just the locking of the torque converter.

When i disconnect either shift solonoid 1 or 2, the breaking symptom in 1st is gone, but it still runs in fail-safe mode.

I took down the bottom pan of the tranny to have a look inside and there is nothing loose and no chunks of metal or anything else floating around in there.
The oil however is very dark, almost black. This I could not see on the dip-stick. There is also a bit of black sedements in the pan but no big bits.

I'm not sure if I should disassemble the tranny more to see if I can find anything else, or if I should just try replacing the oil to see if that does the trick...

Any comments or ideas would be greatly appreciated

[tris91ricer]

Sometimes when the fluid is either low, or really shitty, is when the solenoids start acting up. If I hadn't been near-deathly-ill when my tranny was starting to go, I may have paid more attention to what the error code was and what it meant when i first saw it, instead of ignoring it for my health.

Does your 'power' light flash when you start up?

[Ivan]

No, - there is no flashing in the power light at startup and no current errorcodes on the TCU either, and I had the oil changed at a Subaru dealer in january...

[Ivan]

I just don't get it

I pull'd out the valve-body and took it apart to see if anything looked defective and I actually found two of the spring-valves that seemed to be stuck. Took them apart, cleaned everything and put the valve-body back together again. Confident that I had found the fault I assembled the tranny, put in new oil and fired it up.
But all my trouble made absolutly no difference
It still only runs in 3rd and reverse and it is still blocking when 1st is selected.
And no error codes on the TCU.