Transmission Related Tips
TCU
Trans Filter
Power Light
Manual Button
Trans Types
Motor/Trans Combo Types
These instructions should work for any Legacy from 90-94, or ones that have the power light. The newer models will most likely require a scan tool. These instructions I believe will also work on the SVX as well.
The "Power" light indicates transmission codes. The following self diagnosis will show any fault codes for the transmission.
To perform the self diag test for EXISTING problems
1) Warm up engine by driving at speeds greater than 12mph.
2) Stop vehicle and turn ignition switch OFF.
3) Turn ignition switch ON and make sure POWER indicator lamp comes on.
4) Turn ignition switch OFF.
5) Move selector lever to D and turn manual switch ON.
6) Turn ignition switch ON.
7) Move selector lever to "3" and turn manual switch OFF.
8) Move selector level to "2" and turn manual switch ON.
9) Move selector lever to "1" and turn manual switch OFF.
10) Partially depress accelerator pedal (to turn idle switch off).
11) Check code as displayed on POWER light. Blinking once every 1/4sec is normal.
To perform the self diag test for PREVIOUS problems
1) Warm up engine by driving at speeds greater than 12mph.
2) Stop vehicle and turn ignition switch OFF.
3) Turn ignition switch ON and make sure POWER indicator lamp comes on.
4) Turn ignition switch OFF.
5) Move selector lever to "1" and turn manual switch ON.
6) Turn ignition switch ON.
7) Move selector lever to "2" and turn manual switch OFF.
8) Move selector lever to "3" and turn manual switch ON.
9) Move selector lever to "D" and trun manual switch OFF.
10) Partially depress accelerator pedal (to turn idle switch off).
11) Check code as displayed on POWER light. Blinking once every 1/4sec is normal.
Trouble Code Table
Trouble Code |
Item |
| 11 | Duty solenoid A |
| 12 | Duty solenoid B |
| 13 | Shift solenoid 3 |
| 14 | Shift solenoid 2 |
| 15 | Shift solenoid 1 |
| 21 | ATF temp sensor |
| 22 | Atmospheric sensor |
| 23 | Engine revolution signal |
| 24 | Duty solenoid C |
| 25 | Engine torque control signal |
| 31 | Throttle sensor |
| 32 | Vehicle speed sensor 1 |
| 33 | Vehicle speed sensor 2 |
For the early Legacies there was an external transmission filter kit that was added on. The primary reason was that they were producing too much metal shavings and the tranny would wear out prematurely. The filter kit is like $20, not too expensive. The automatic transmissions are anything but stellar, but the filter kit does help. Actually heat is the big killer, so if you do a rebuild, add an external transmission cooler.
To check if you have the filter installed, look over by your battery, you should see a small canister looking thing that is hooked up to the radiator. Here's a nice little pic.
Here are the Subaru part numbers for the Transmission filter kit, and pan gasket.
Trans Filter Kit # 31099AA091
Trans Pan Gasket # 31397AA040
The little green power light serves a couple functions. I guess it's main purpose is as a check transmission light when there is problems. The procedure on how to get the codes for the TCU is above. The light also is supposed to tell you when you are in "power mode." When you dump it, the light will come on. Essentially the transmission computer changes the shift points and shifts later to allow the engine to rev higher for more power/performance. You aren't getting any more power when the light is on. The transmission is just changing when it shifts into the next gear.
The manual button has some controversy as two what its function is. But I'm here to disavow any of those rumors. Firstly, the automatic transmission normally runs a power split of 90% front 10% rear. This is under normal driving conditions. Secondly, the manual button ONLY works when the shift lever indicator is in the positions "3" or "2".
Ok, so you're ready to hear what this thingy does. It is a very primitive version of traction control. When the shift lever is either 3 or 2, and the manual button is depressed, it will keep the transmission from going into first gear. By doing this, you have less torque, more evenly distributed power, and a less chance to slip and slide around.
So to recap, when the shift lever is in the 2 position the transmission stays in 2nd gear. When the shift lever is in the 3 position the transmission chooses between 2nd and 3rd gear. If the shift lever is any other position then the two above, the manual button does absolutely positively nothing.