Narrowpath Posted April 4, 2011 Share Posted April 4, 2011 (edited) I need help guys...... I had torque bind when I bought this car a month ago. Read up on everything and did the FWD fuse which eliminated issue. I ran the code on the tranny and got a 24, which was duty c. I then started to noticed the FWD fuse while in was beginning to fail and torque bind was occurring when it was in. I just finished pulling out the transfer clutch and filing down the grooves on reduction shaft to make them smooth again, replaced DUTY C and then buttoned it back up with new fluid. Ran perfect for a couple miles and had no issues turning sharp....... and then it started again after I shut the car off and then started it. Feels like the brakes are on and there is a whine coming from tranny just like before i removed the duty c. I don't know what else to do........ready to throw in the towel on this car...... Need some help please!!!! It is a 93 Subaru Legacy AWD non-turbo. Only 140 k on it. Edited April 4, 2011 by Narrowpath Quote Link to comment Share on other sites More sharing options...
bstone Posted April 4, 2011 Share Posted April 4, 2011 Go ahead and clear the TCU. Unplug the negative terminal for a few hours and try again. Repull the codes if it comes back. Quote Link to comment Share on other sites More sharing options...
wtdash Posted April 4, 2011 Share Posted April 4, 2011 ^ +1 I'd also try swapping the TCU. A '92-94 will be a direct replacement. Td Quote Link to comment Share on other sites More sharing options...
Narrowpath Posted April 4, 2011 Author Share Posted April 4, 2011 Thanks for that.....unplugged till morning. Where is the TCU located on the legacy.... Quote Link to comment Share on other sites More sharing options...
ericem Posted April 4, 2011 Share Posted April 4, 2011 It is located under the driver side its a gold box with the connectors facing down you will need to remove the plastic knee cover. It requires only removing 2 nuts and 3 connectors all easy access! Quote Link to comment Share on other sites More sharing options...
idosubaru Posted April 4, 2011 Share Posted April 4, 2011 did you check the clutches/plates? does the FWD fuse work now with the new Duty C? as a last resort pull the rear half of the driveshaft, and cut power to the Duty C (takes 30 seconds once you know which wire) so that the car is driveable in FWD. if it's completely gone and you have torque bind you don't need to cut the power to the Duty C. but i'd know which wire you need to pull or have the rear shaft in the trunk in case it starts operating again. it's at least an easy way to get a daily driver back on the road and not damage anything else. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted April 4, 2011 Share Posted April 4, 2011 The clutch pack itself is cheaper than the duty-c - I would have definitely replaced that while in there. With it locked up into torque bind they were probably overheated and damaged anyway. TCU's do fail as well - worth a try. GD Quote Link to comment Share on other sites More sharing options...
Gloyale Posted April 4, 2011 Share Posted April 4, 2011 TCU's do fail as well - worth a try. GD Yes they do fail. I've seen at least 3 cars where installing a new TCU solved the Torque bind. (after replaceing clutches and duty c DIDN'T) Quote Link to comment Share on other sites More sharing options...
Narrowpath Posted April 4, 2011 Author Share Posted April 4, 2011 I really think it is electrical. If I shut the car off and on a couple times the torque bind is now gone. Runs perfect for a few miles and then starts back up without explanation. If the clutches were bad it seems they would consistantly be failing. It really feels like an electrical problem because it is now random...... guess I better look for a tcu. Quote Link to comment Share on other sites More sharing options...
Narrowpath Posted April 5, 2011 Author Share Posted April 5, 2011 (edited) I also found that by shutting the car off and on a few times and removing the key it would eventually reset so that the power light did not flash upon starting....If the power light was flashing..... bad torque bind.......no flashing......smooooooth...... Pulled a TCU out of a wrecked 93 Legacy today....found a few more goodies while I was in there... Will plug and play later.......PRAYING THIS WILL DO IT!!!!!! Edited April 5, 2011 by Narrowpath Quote Link to comment Share on other sites More sharing options...
ericem Posted April 5, 2011 Share Posted April 5, 2011 I forgot to mention I bought my 94 legacy turbo with non working awd. Opened the transmission saw the clutch housing had actually cracked! I swapped in a good 4eat and guess what torque bind!! Swapped the tcu with one from another legacy turbo no more torque bind and again had the same issue random power light flash on startup but dont recall it torque bind going away turning it on and off sometimes. Good luck pretty sure you found the source of your problem! Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted April 5, 2011 Share Posted April 5, 2011 I also found that by shutting the car off and on a few times and removing the key it would eventually reset so that the power light did not flash upon starting... the flashing AT Temp light at start up means there was an electrical problem the last time the car was driven. if you start the car and then turn it off with out driving it you will clear the flashing light. Quote Link to comment Share on other sites More sharing options...
Narrowpath Posted April 5, 2011 Author Share Posted April 5, 2011 TCU in......took it for a test drive..........so far so good. Rolls very nice and smooth, takes tight corners, no popping or bind......could it be solved??? Keeping fingers crossed as I drive 40 miles in the am..... Quote Link to comment Share on other sites More sharing options...
Olnick Posted April 5, 2011 Share Posted April 5, 2011 You focus on the driving. We'll keep our fingers crossed for you! Quote Link to comment Share on other sites More sharing options...
Narrowpath Posted April 6, 2011 Author Share Posted April 6, 2011 Looks like the TCU took care of it. Drove really nice all day. I am breathing a little easier now. Thanks to all the help provided over the past month. This is a fantastic forum. From what I have learned a TCU problem is hard to diagnosis, but for a $40 dollar junk yard part it seems worth doing a swap before you spend the weekend pulling out the rear of the tranny. My .0001 cents worth! Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted April 6, 2011 Share Posted April 6, 2011 Good to hear you fixed it! Quote Link to comment Share on other sites More sharing options...
eulogious Posted April 6, 2011 Share Posted April 6, 2011 http://www.ultimatesubaru.org/forum/showthread.php?t=110121&highlight=torque+bind Surprised that didn't come up in a search, since I have found, fixed, and took pics of the process on what it takes to fix it, well what usually is the culprit anyways. TCU errors are not hard to find at all. The TCU is really stupid, especially in the older legos. The pins trace right to the components, and there are very few components as a whole compared with some electronics, so tracing what needs to be traced is really easy with these primitive computers. Using the same process, you can figure out what other components might have failed as well. I have a TCU, well two actually, that I need to fix. One has a bad duty B transistor, and the other a bad duty c transistor. So this is not an uncommon problem. In fact any computer that is coming up onto 20 years old is going to run into issues like this... So if you are daring and good with a soldering iron you should be able to fix you broken TCU right up! I can help you as much as I can as well with any questions that might come up... Either way, glad you fix it! Quote Link to comment Share on other sites More sharing options...
kmix99 Posted July 3, 2012 Share Posted July 3, 2012 I'm reviving this post as I have run into the same issues on my 1992 Legacy LS AWD. First I changed the tranny fluid 3 times, and the rear differential fluid twice. Next, I replaced the Duty C solenoid assembly and gaskets, transfer gear set (new), and transfer drive-gear shaft with seals (new). Transfer clutch plates looked fine so I left them alone. Got everything back together only to fine out I still have the dreaded code 24 flashing. Next, I removed the TCU and traced the circuit pathway for the Duty C (big thanks for the great pics posted by "Eulogious" in "Fixing a fried 4EAT TCU" post). I desoldered the corresponding Duty-C transistor off the board and it tested fine. Nothing else on the board looked burned/ fried. All of the under-dashboard wiring from the TCU to the engine compartment tests ok (no breaks or shorts), and I have a good ground to the solenoid. Service Manual Test for Duty-C: When I test the output at TCU pin 3 (white wire with black stripe) with shifter in 1st gear, I get 8.5 volts. With the gas pedal fully depressed, I get 5.4 volts. Service Manual says voltage should be 0.5v at pin 3 with the gas pedal depressed. Not sure why I'm off on this reading. With FWD fuse installed, I get approx 12 volts at pin 3 with or without pressing the gas pedal. Driving with the FWD fuse installed makes no difference...still have binding. At this point, I'm either going to find a used TCU and swap, or remove the center drive-shaft. What are the chances I'll find a good TCU of this vintage that doesn't have the same problem? Man, this is frustrating...... Quote Link to comment Share on other sites More sharing options...
Ricearu Posted July 3, 2012 Share Posted July 3, 2012 to fully disengage the duty c, the tcu needs to send 12v or so to the solenoid. it's in awd with NO power to the solenoid. 12v should disengage. do you have torque bind with the FWD fuse in? Quote Link to comment Share on other sites More sharing options...
kmix99 Posted July 13, 2012 Share Posted July 13, 2012 I'm reviving this post as I have run into the same issues on my 1992 Legacy LS AWD. First I changed the tranny fluid 3 times, and the rear differential fluid twice. Next, I replaced the Duty C solenoid assembly and gaskets, transfer gear set (new), and transfer drive-gear shaft with seals (new). Transfer clutch plates looked fine so I left them alone. Got everything back together only to fine out I still have the dreaded code 24 flashing. Next, I removed the TCU and traced the circuit pathway for the Duty C (big thanks for the great pics posted by "Eulogious" in "Fixing a fried 4EAT TCU" post). I desoldered the corresponding Duty-C transistor off the board and it tested fine. Nothing else on the board looked burned/ fried. All of the under-dashboard wiring from the TCU to the engine compartment tests ok (no breaks or shorts), and I have a good ground to the solenoid. Service Manual Test for Duty-C: When I test the output at TCU pin 3 (white wire with black stripe) with shifter in 1st gear, I get 8.5 volts. With the gas pedal fully depressed, I get 5.4 volts. Service Manual says voltage should be 0.5v at pin 3 with the gas pedal depressed. Not sure why I'm off on this reading. With FWD fuse installed, I get approx 12 volts at pin 3 with or without pressing the gas pedal. Driving with the FWD fuse installed makes no difference...still have binding. At this point, I'm either going to find a used TCU and swap, or remove the center drive-shaft. What are the chances I'll find a good TCU of this vintage that doesn't have the same problem? Man, this is frustrating...... An update: I replaced the Transmission Control Module (Original Subaru Part #: 31711AB354) with a used one from Ebay (Subaru Part Number: 31711AC031). No more flashing Power light and the torque bind is gone!!!! This was purely and electrical problem on the TCU circuit board causing the code 24 Duty-C error. From my limited testing, my original TCU had a problem in one of the integrated circuit chips on the board that sends a signal to the base terminal of the transistor for the Duty-C circuit. This controls the voltage output to the Duty-C solenoid. Quote Link to comment Share on other sites More sharing options...
bstone Posted July 13, 2012 Share Posted July 13, 2012 Mazel tov! Quote Link to comment Share on other sites More sharing options...
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