1991 liberty TCU (auto computer)

velocityboy · Post by **velocityboy** » Mon Mar 18, 2013 10:42 am

Does anyone have a TCU ( computer for the auto box) to suit a 1991 Liberty awd. I am chasing a shift problem and now am clutching at straws and wont to change the TCU hoping it's that. The computer I have is from a JDM RS liberty but I think any domestic one will do.

RSR 555 · Post by **RSR 555** » Mon Mar 18, 2013 11:55 am

I have a couple but would be best to match the number on it. Something like EL in large letters

velocityboy · Post by **velocityboy** » Tue Mar 19, 2013 7:28 am

Thanks, my son has taken my Brumby again so I will get back to you in couple of days.

guyph_01 · Post by **guyph_01** » Tue Mar 19, 2013 12:05 pm

I got one too fron a N/A Liberty if Pauls ones don't suit:)

vincentvega · Post by **vincentvega** » Tue Mar 19, 2013 7:39 pm

you dont need to match them exactly. any gen1 NA tcu will work they just have different behaviors.

I preferred the latest S2 TCUs myself. Much better control of the torque converter lockup than the earlier models.

RSR 555 · Post by **RSR 555** » Wed Mar 20, 2013 10:45 am

vincentvega wrote:you dont need to match them exactly. any gen1 NA tcu will work they just have different behaviors.

That is good to know. Have you had any experiences with the Gen2 Liberty auto TCUs? My son's car (AWD sedan) seems to be a bit sluggish compared to other auto Libertys.

velocityboy · Post by **velocityboy** » Mon Mar 25, 2013 9:02 am

The TCU that is in the car is from a '91 RS Liberty half cut that I used to do my Brumby conversion. The numbers on it are, in large letters EL under that is 31711 aa423, under those are a64-000-600 9919.
I will take you guys advise as to what will work but I geuss if I could get as close to the orginal it will reduce any problems.
I have now got a '97 forester box in the car but neither box has shifted properly so I don't think it's because the forester box is different in some way.

Let me know what you have and how much you want for it and we'll go from there.

RSR 555 · Post by **RSR 555** » Mon Mar 25, 2013 3:24 pm

Ok. The plot thinkens.. I will have a TCU that you can have for $50 plus postage but after reading your comment about using the Forester box in the Liberty, this is were I think your issue is. From my experience with them, the Foz and Impreza use a different wiring config to the Liberty setup. I tried a Liberty box in a Impreza once and end endless issues. I'm not into wiring, so I have no idea what the differences could be, maybe grab wiring diagrams for both models and compare.

velocityboy · Post by **velocityboy** » Mon Mar 25, 2013 6:14 pm

The number on the box is exactly the same between the Lib and Forester, the wiring harness and pin out is the same also. I am not expert with these things but I was haveing the same trouble with the origanal Liberty box as I am with the forester one so I am geussing it's something else.
The problem is it goes randomly into limp home mode (will only select 3rd gear).
I had previously had a fault code in the ECU when the airflow metre failed and I can't clear the code, would that make a difference?
The only fault code in the ecu is still just the 1 for the airflow meter.
Even though I have NEVER solved a problem by changing an ecu or tcu I have got desperate thought it may be worth the punt.

RSR 555 · Post by **RSR 555** » Mon Mar 25, 2013 7:26 pm

Ok, if the number were the same then there is no issue there but the RS shouldn't have the same number as the Impreza or Foz.

Definitely wouldn't hurt to clear the codes.

Who did the wiring? and did they leave the Subaru Select Monitor plug in the system? if so, could be best to get it on the machine.

vincentvega · Post by **vincentvega** » Mon Mar 25, 2013 10:42 pm

try another TCU but I have used a gen1 turbo TCU with an NA box. Only problem was the rev limits are incorrect and you will hit the ECU rev limiter before the TCU shifts.

If you have swapped boxes and still have the same problem then you have a wiring or TCU issue.