92 AT computer codes. Continuous flashing?

[FerGloyale]

Hey all.

A little discussion about early Legacy (oBD I) Automatic Trasn computers and codes.

There is a lot of conflicting info from different years.

But for Early ones this is my familiarity.

"AT temp" light flashes 16 times at startup to indicate a detected fault during last drive cycle.  This is not code 16, it is just the indicator that there IS a code to be pulled.

So, use secret handshake........

Key off, shifter to D, with power button pressed.

Then key on, depress power button

shift to 3rd, press power button

shift to 2nd, depress power button

Shift to 1st, press power button

Tap throttle past 1/2 way.

Now this should output codes with short/long blinking like enigne codes............3 short, 4 long would be code 34.......

 

Now, what I'm getting is a Steady, constant blink......nothing to give it any code.  Can't find info on this condition.  Does anyone know?  Does this mean teh TCU is boogered and can't self-diagnos?  

[wtdash]

Confused...are you getting the 16 flashes w/the Key On at each start-up? If not, did you see this: https://www.surrealmirage.com/subaru/trans.html

Under #11 of 1st section: "..... Blinking once every 1/4sec is normal."..

 

 

 

Edited August 29, 2019 by wtdash

[FerGloyale]

Yes, I did get 16 flashes on startup.

Car is also exhibiting torque bind while parking.

Duty C just replaced with brand new OE From subaru.

Clutch drum grooves ground out and polished.

Clutch plate clearance checks OK.

Car has 270k miles.

I may have turned the key on and off one too many times before getting code output......it only tells you code from last drive.  So maybe that's why Im getting no codes just blink?

[FerGloyale]

Ah.....Thanks for the link to that chart Dash....

I had forgot the reverse procedure for outputting PAST codes.

Just went and did it and still getting Duty C code.

Thinking this TCU is dead.

Wiring Ohms out, Solenoid is new......so that leaves the TCU or the Dropping resitor?  Guess that's the next test.

[wtdash]

...and you cleared the codes and it comes back? Did you test w/the FWD fuse? If the fuse works (no torque bind), then it's mechanical; if no change then it's electrical/electronic, from my past learnings on here. :-)

 

 

[FerGloyale]

29 minutes ago, wtdash said:

...and you cleared the codes and it comes back? Did you test w/the FWD fuse? If the fuse works (no torque bind), then it's mechanical; if no change then it's electrical/electronic, from my past learnings on here. :-)

 

 

 

That is a good piece of basic testing.

But, in this case, hmmm....Well, the torque bind is intermittent.  Most only long drives.

If the transitor on the TCU board that drives the "C" is just a little flaky when hot, the FWD fuse would still work for full FWD, but yet not properly regulate flow for slow moving slip vs. grab during parking.

IDK, I've got some test driving to do.  And I gotta try to dig up a 3.9 TCU in my stash for testing.

[GeneralDisorder]

I have seen several bad TCU's that throw Duty-C codes but the solenoid is good. It's usually the gen 1 legacy cars. Gen 2's the solenoids fail. 

GD

[wtdash]

Quote

IDK, I've got some test driving to do.  And I gotta try to dig up a 3.9 TCU in my stash for testing.

From what I've read on here, you should be able to use any phase 1 Legacy TCU ('90-'98)...FD ratio doesn't matter.

 

Edited August 30, 2019 by wtdash

[idosubaru]

On 8/29/2019 at 6:17 PM, FerGloyale said:

 

IDK, I've got some test driving to do.  And I gotta try to dig up a 3.9 TCU in my stash for testing.

Doubt this matters and you know these better than me but I’ve swapped different ratio EJ TCUs to test if it made a difference and noticed no difference.