Transmission Gremlins

96 SVX 106k
1. Lately when driving with the transmission in "3", I have noticed that it sometimes is reluctant to upshift from second to third. I will be driving along at constant throttle around 45mph and it stays in 2nd. If I lift up on the throttle it shifts to third.

2. Yesterday morning, I had the lever in "3" and the transmission was in third. I was driving on level ground at constant throttle around 45 - 50 mph and suddenly the rpms jumped (I assume it downshifted into 2nd). It stayed like that for 3 -5 seconds and then apparently shifted back into 3rd. This happened three times on about a 5 mile stretch.

3. Last night (and this morning) when driving with the transmission lever in the "1", "2" or "3" position at constant speed and on level surface, if I lift entirely off the throttle the rpms drop to between 850 - 1250 and the car feels as if I have shifted into neutral. It only gradually slows down - there is no compression braking. I can blip the throttle and take the rpms up to 2500 with no apparent effect, again just like the transmission is in neutral. If I drive with the lever in "D", all seems well. I checked the transmission fluid with the engine and operating temperature, engine running and transmission in "P" and it it about 1/4 inch above the hot full mark. After letting the car sit overnight I checked the fluid level before starting the car and it was about 1 1/2 inch above the hot full level. I would have thought that the level should check lower when cold than hot. Any ideas what is going on here? Any suggestions?

4. I had the duty solonoid C replaced three months ago at 102K and that is the last time transmission fluid would have been added. I had not checked the level since then until yesterday.

[immortal_suby]

It sounds like a failed or unplugged tranny resistor to me - the resistor on the firewall next to the battery.
Do you get a blinking power light on startup?

Search here or check the how to folders for pulling up trouble codes from the transmission computer and let us know what you find.

My battery is near the front of the car on the driver's side. There is a resistor looking thing on the fender well along side the battery. It is plugged in. Is there any way to test it? I do NOT get any blinking power light when I start the car. Does it make any sense to you that the transmission fluid checks just a little high when the car is running and at operating temperature, but measures even higher when the car is cold and checked with the engine off?

[immortal_suby]

When the car is not running the ATF in the cooler and lines runs back into the tranny - this will give you a higher reading.

You can test the resistor by unplugging it and using an ohmeter across the terminals. It should be about 10.5 ohms.

The sudden downshifting/upshifting sounds like it could potentially be a TPS problem (or something else throttle-related). Have your TPS checked, throttle bodies cleaned, and check all the connection on your ECU and TCU.

As a first step I put an ohm meter on the resistor and it reads 12.5 ohms. Is that far enough off to diagnose it as bad? New ones are $72. I found some additional diagnostics in my file for the TCU and throttle position sensor, so wil check them this weekend.

[SVXer95]

I doubt that the resistor is bad. I have no idea what the resistance is supposed to be, but 12.5 ohms is quite low as far as resistors go, so there is continuity.

[immortal_suby]

It should be 10.5 but at 12.5 you shouldnt be seeing a problem. A lower resistance would cause the gear hunting. You could probably get a used one from a scrapyard or get the right materials from radioshack for alot cheaper. A few people here have done this - a search should turn up their results.

I'd try cleaning the TPS next and see what happens. Make sure to put hashmarks on it before you remove it so you can get it set back on right. There is also a procedure here either in a post or in the how-to lockers for checking the resistance of the TPS.

I adjusted the TPS to .50 volts and that took care of the sudden downshifting, but did nothing for the lack of engine braking when the transmission lever is in 1, 2 or 3. I cleaned the throttle body and cleaned the TPS with no noticeable change. The throttle body had never been cleaned in its 106k life, yet was not very dirty. Perhaps the Red Line SI-1 gets credit for this as I do use it regularly. While I had the TPS off, I checked the reisistance across the outside terminals and it was 5700 ohm. I have read elsewhere that it should be either 4000 or 5000 ohm. Could this be causing the lack of engine braking?

[lee]

The spec for the resistor is 9 to 15 ohms, so you're OK there.

You can't tell ATF fluid levels (cold or hot) without the engine running, the car level, and the transmission in Park. So your test of the cold temp has to be redone to get the correct value - it's best to check at operating temp anyway.

As to engine braking, here's a cut from something I put together from Subaru and other sources on that issue (first letter/number is the gear selected on the console, second number is the gear the transmission is actually operating in, i.e., D-3 means "drive is selected, but the transmission is currently operating in third gear):

D-1 or 3-1 Operating Mode
The input shaft powers the rear sun gear clockwise. When the Forward clutch is applied, the O.W.C. 3-4 outer race (forward clutch hub) is attached to the front carrier. With the O.W.C. 3-4 operating, the rear internal gear can only go clockwise. With the O.W.C. 1-2 operating, the forward clutch drum can only go clockwise. Output power is through the rear carrier. During coast mode, the O.W.C. 3-4 is released and there is no engine braking.

D-2, 3-2, Or 2-2 Operating Mode
Again, the input shaft powers the rear sun gear clockwise. When the forward clutch is applied, the O.W.C. 3-4 outer race (forward clutch hub) is attached to the front carrier. The band is also applied which holds the front sun gear stationary. Output power is transmitted from the rear carrier (front internal gear). During the coast mode, the O.W.C. 3-4 is released and there is no engine braking.

D-3, 3-3 Operating Mode
The input shaft powers the rear sun gear clockwise. When the forward clutch is applied, the O.W.C. 3-4 outer race (forward clutch hub) is attached to the front carrier. The high clutch is also applied and the front planetary carrier is therefore powered. In this case the planetary gear set is locked up. During the coast mode, the O.W.C. 3-4 releases the rear internal gear and there is no engine braking.

D-4 Operating Mode
The input shaft powers the rear sun gear clockwise. When the forward clutch is applied it doesn’t affect the power flow. It freewheels through the O.W.C. 3-4. When the high clutch is applied, the front planetary carrier is powered clockwise. Since the band is applied, the front sun gear is held stationary. The output is clockwise through the front internal gear (rear planetary carrier). Engine braking occurs during the coast and deceleration modes. Neither O.W.C. is used.

2-1 Operating Mode
The power flow is the same as in the other 1st gears except as follows. The rear internal gear is held by the overrunning clutch instead of by the O.W.C. 3-4. In addition, the forward clutch drum is held by the Low/Reverse brake instead of the O.W.C. 1-2. Engine braking occurs during coast and deceleration due to conditions described above. The overrunning clutch is “ON” and the Low/Reverse brake is “ON.”

Hope this helped - especially since it was so long.

Lee - Thanks for the explanation. You are obviously MUCH more technically knowlegable than I. But I unless I misunderstand, some of what you wrote doesn't jive with what I have experienced in driving the car for the past seven years. I have ALWAYS experienced engine/compression braking in 1-1, 2-2, and 3-3. Now I NEVER get that. For example, I can be driving at 80 mph in 3-3, lift off the throttle, and the rmps drop to between 850 - 1250 and it just feels like I have just shifted into neutral. Maybe I am not expressing the problem correctly?

[lee]

Originally posted by Jack
Lee - Thanks for the explanation. You are obviously MUCH more technically knowlegable than I. But I unless I misunderstand, some of what you wrote doesn't jive with what I have experienced in driving the car for the past seven years. I have ALWAYS experienced engine/compression braking in 1-1, 2-2, and 3-3. Now I NEVER get that. For example, I can be driving at 80 mph in 3-3, lift off the throttle, and the rmps drop to between 850 - 1250 and it just feels like I have just shifted into neutral. Maybe I am not expressing the problem correctly?

I can't dispute what you feel, and honestly I would have to go check myself as I've never thought much about it (or drive much in 3, 2, etc). What I reported for engine breaking came from a paper on the Subaru site endwrench.

The resistor value I know is true, as well as checking the fluid. The rest, as I said, is just me reporting - not much tech knowledge here.

[lee]

Jack,

My next suggestion would be to download part 1 of 3 of the transmission manual I put in my personal locker. The table of physical symptoms validates your recollections of proper behavior and lists potential problems that result in lack of engine braking (As with my long post, I didn't create the words myself from knowledge, I'm just a collector of info due to tranny issues myself and the frustration that causes). There's also a bunch of other stuff about tests you can do yourself to get an idea of what might be wrong, i.e., time lag tests, etc.

Thanks! It is printing right now. I will let you know how things progress.

This does not look good. The manual lists three possible reasons for no engine braking in each of the three gears (1,2 and 3). Since I have no engine braking in any of those three gears I looked to see if there was any common problem area for all three. The only common one is the control valve and that is something I am not going to tackle. Looks like time for professional help. One other possibility is that the manual is using the term "engine brake is not effected" differently that what I am referring to as engine braking. The reason I think this may be so is when I read the Road Test procedures for "Engine Brake Operation", I think my car will pass the test. Will check on way home tonight. What I am referring to as engine braking is the slowing of the car you get from engine compression when you let off the throttle. This is not very noticeable in D, but in the other gears it should be very much like letting off the throttle in a low gear in a manual transmission.