Jump to content


Welcome to Ultimate Subaru Message Board, my lurker friend!

Welcome to Ultimate Subaru Message Board, an unparalleled Subaru community full of the greatest Subaru gurus and modders on the planet! We offer technical information and discussion about all things Subaru, the best and most popular all wheel drive vehicles ever created.

We offer all this information for free to everyone, even lurkers like you! All we ask in return is that you sign up and give back some of what you get out - without our awesome registered users none of this would be possible! Plus, you get way more great stuff as a member! Lurk to lose, participate to WIN*!
  • Say hello and join the conversation
  • Subscribe to topics and forums to get automatic updates
  • Get your own profile and make new friends
  • Classifieds with all sorts of Subaru goodies
  • Photo hosting in our gallery
  • Meet other cool people with cool cars
Seriously, what are you waiting for? Make your life more fulfilling and join today! You and your Subaru won't regret it, we guarantee** it.

* The joy of participation and being generally awesome constitutes winning
** Not an actual guarantee, but seriously, you probably won't regret it!

Serving the Subaru Community since May 18th, 1998!

Guest Message by DevFuse
 

Photo
- - - - -

how does TCU determine AWD or FWD?


  • Please log in to reply
34 replies to this topic

#26 crazyhorse001

crazyhorse001

    Subaru Fanatic!

  • Members
  • 469 posts
  • Greeneville

Posted 12 April 2008 - 06:17 PM

Considering I have the manual button, for the secret handshake, I ought to be able to figure SOMETHING out LOL

#27 grossgary

grossgary

    Elite Master of the Subaru

  • Members
  • 19,612 posts
  • WV

Posted 12 April 2008 - 06:23 PM

you did the same swap i did - 95 into a 96. i guess you swapped the rear diff to match? i didn't know what to think since i swapped AWD to FWD and EJ25 to EJ18, but since yours was just the trans i'm wondering if we won't have the same codes.

be interesting to see. i assume you're going to try and pull the code?

#28 johnceggleston

johnceggleston

    Lite Master of the Subaru

  • Gold Subscribers
  • 6,187 posts
  • Virginia

Posted 13 April 2008 - 01:09 PM

Ok, this thread just became relavent to me. I swapped a '95 OBD1 trans into my SVX & have the flashing AT TEMP light @ startup. Mysteriously, I also have no FWD light with the fuse in. Factor this into your thoughts on this issue.
The car drives flawlessly, still does the torque interrupt during shifts, and generally works as advertised.

For the record:
Trans is a '95 Impreza 4.11 AWD
Car is a '96 SVX


do you have torque bind.

when my 95 leg sedan with a 96 leg wagon auto trans got torque bind and a flashing AT temp light i put in the fuse and the FWD light came on and the flashing light and TB went away. we drove it like this for a while. then, occasionally, the torque bind and flashing light would come back even with the fuse in. when this happened the FWD light would go out.

conclusion, if you put in the fuse and the FWD light comes on the duty c is working, if the FWD light doesnot come on then the duyt c is not working. i haven't studied this problem in depth so my conclusion may be wrong, but the facts are correct. in my car, if the duty c is not working the fwd light will not come on.

we finally removed the rear section of drive shaft until we replace the duty c.

#29 Gloyale

Gloyale

    It's a sickness

  • Members
  • 8,810 posts
  • Corvallis, OR PNW

Posted 13 April 2008 - 01:24 PM

the phase 2 trans, 99 and up, has at the very least, 2 more speed sensors. i think they are internal. they are the simple one like the one on the rear extention housing. this by it self adds 2 more wires to the wiring harness / connector. i don't know what other changes they may have made in 99.


Can you show any literature or pics to back this up?

Considering that the TCU already recieved speed signals from 2 sensors, I don't understand why 2 more would be added?

#30 Gloyale

Gloyale

    It's a sickness

  • Members
  • 8,810 posts
  • Corvallis, OR PNW

Posted 13 April 2008 - 01:27 PM

Mysteriously, I also have no FWD light with the fuse in. Factor this into your thoughts on this issue.



installing the FWD fuse connects a signal circuit on the TCU to ground.

One side of the fuse holder is connected to the TCU, the other should be bolted straight to the car body for ground. Fairly close to the FWD fuse holder itself. Check that the grounded side of the fuse holder actually is grounded.

#31 johnceggleston

johnceggleston

    Lite Master of the Subaru

  • Gold Subscribers
  • 6,187 posts
  • Virginia

Posted 13 April 2008 - 07:00 PM

Can you show any literature or pics to back this up?

Considering that the TCU already recieved speed signals from 2 sensors, I don't understand why 2 more would be added?



my first clue was the different connectors with different number of pins between the 99 phase 2 and the 95-98 phase 1. for 10 years they had been using the TZ102Z... series trans, in 99 they went with the TZ1A2Z......
2ND was an ad on ebay for a trans wirring harness, the one that goes into the the trans case, for a 99 outback auto trans. it had more wires and what appeared to be 2 more of the speed sensors like the one in the transfer case.
3RD some one posted a link to a 99 trans diagram of some kind and it showed me something to confirm my thinking. the added sensors could be temp or something else but they looked like the speed sensors to me.

but i'm not an engineer nor a subaru expert, so i could be wrong.

#32 crazyhorse001

crazyhorse001

    Subaru Fanatic!

  • Members
  • 469 posts
  • Greeneville

Posted 15 April 2008 - 10:24 AM

do you have torque bind.

when my 95 leg sedan with a 96 leg wagon auto trans got torque bind and a flashing AT temp light i put in the fuse and the FWD light came on and the flashing light and TB went away. we drove it like this for a while. then, occasionally, the torque bind and flashing light would come back even with the fuse in. when this happened the FWD light would go out.

conclusion, if you put in the fuse and the FWD light comes on the duty c is working, if the FWD light doesnot come on then the duyt c is not working. i haven't studied this problem in depth so my conclusion may be wrong, but the facts are correct. in my car, if the duty c is not working the fwd light will not come on.

we finally removed the rear section of drive shaft until we replace the duty c.


I'm also running with 1/2 a driveshaft, as I didn't have the rear diff to swap in. So, what you're saying is, when the duty C dies, The FWD light goes out. Interesting.

As for pulling codes. I may have the Manual sw., but I don't have a stinkin' power light, so no way to output the stupid codes!

#33 johnceggleston

johnceggleston

    Lite Master of the Subaru

  • Gold Subscribers
  • 6,187 posts
  • Virginia

Posted 16 April 2008 - 08:29 AM

I'm also running with 1/2 a driveshaft, as I didn't have the rear diff to swap in. So, what you're saying is, when the duty C dies, The FWD light goes out. Interesting.

As for pulling codes. I may have the Manual sw., but I don't have a stinkin' power light, so no way to output the stupid codes!


i don't reall know if the procedure is the same for cars without the power light, but i think the power light was replaced by the AT TEMP light for trans warning purposes. maybe for code reading as well????

#34 Legacy777

Legacy777

    Moderator

  • Moderator
  • 12,563 posts
  • Houston, Tx

Posted 18 April 2008 - 11:49 AM

my first clue was the different connectors with different number of pins between the 99 phase 2 and the 95-98 phase 1. for 10 years they had been using the TZ102Z... series trans, in 99 they went with the TZ1A2Z......
2ND was an ad on ebay for a trans wirring harness, the one that goes into the the trans case, for a 99 outback auto trans. it had more wires and what appeared to be 2 more of the speed sensors like the one in the transfer case.
3RD some one posted a link to a 99 trans diagram of some kind and it showed me something to confirm my thinking. the added sensors could be temp or something else but they looked like the speed sensors to me.

but i'm not an engineer nor a subaru expert, so i could be wrong.


I know at least one additional sensor is the torque converter speed sensor. That's just from memory. I'd have to lookup what else has changed.

#35 crazyhorse001

crazyhorse001

    Subaru Fanatic!

  • Members
  • 469 posts
  • Greeneville

Posted 18 April 2008 - 01:22 PM

I pulled my codes, yep the AT TEMP gave them to me. I have one code...Duty C. So... I'll be cracking the case on my old tranny to pull it. I'll swap it in when I get the cash to buy a 4.11 rear diff to swap.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users