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Guest Message by DevFuse

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Does anyone ACTUALLY KNOW how to do the TC lockup mod?

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8 replies to this topic

#1 Xanadu62


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Posted 17 February 2011 - 04:01 PM

Just a question that I can't seem to find the answer to after spending the past 2 hours on Google. Everyone either says to not do do it, or that it is a great mod and it helped them out alot without providing much if any documentation:banghead:. I want to actually install a switch to lock up the torque converter, not read about the good and bad. I have a 95 lego postal with a bad MAP, and the TC only locks up once per trip for half a mile before deciding to keep the motor at 3k regardless of speed. I want to be able to lock it up so I can save some gas and my tranny fluid. The trans already throws a code 16, so I'm not worried about the electronics at this point. I'm kinda surprised that the info is so hard to find. I did a search for the duty C lockup mod and found a full writeup in a relatively short time. I'm hoping someone has a writeup or a link (preferably with pics) to one so that I can fix my car instead of hearing the "just fix it the right way" explanation. If I could afford to fix it, I would have bought a TT front clip by now. Thanks guys.

#2 johnceggleston


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Posted 17 February 2011 - 06:12 PM

the 16 flashes you see at start up is only an alert signal like a CEL, not the actual trans code. if your TC is not locking up it is likely that you have a bad solenoid in the trans or maybe a bad wire connection. there is one that is responsible for the lock up i think.

and the TC lock up mod is news to me. i haven't heard of it before.

search for ''transcodes'' and see if you can learn how to read the actual trans code. there is a black? connector under the dash and you have to ground out pin# 6, i think. do a search.

#3 nipper


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Posted 18 February 2011 - 12:47 AM

The torque converter is always locking and unlocking once you are out of 1st gear. this is optimized for max MPG and the damage you can do to your driveline really is not worth the 1/2 mpg you will gain. You will get

besides before you do any mod you have to find out why you have a fault light. Did you ever think that the trouble light can be telling you the fault is keeping your TC from locking up like it should?

When was the last time the fluid was changed, as that can affect it, as well as a few other sensors.

There realy is no lockup mod for subarus because of the way it works, but as i say, your car your money.

#4 Xanadu62


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Posted 18 February 2011 - 10:33 AM

I know the solenoid is good, because it actually will lick up and firm up the driveline. The problem I am having is that it will unlock itself after a very short time and never do it again until I restart the car. I just want to do it in fourth so I can have a "normally" operating transmission. Personally, I would rather install that third pedal and fix everything, but I have less than no money.

#5 mdjdc


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Posted 18 February 2011 - 11:57 AM

You aren't paying attention. The guys are trying to lead you in the right direction. The fault code you are getting at steartup is the transmission control module telling you that one of the solenoids in the trans has failed. They are easy to replace and not all that expensive. you may be cahsing your tail with the "mod" you are talking about if you don't replace the faulty solenoid. Read up on how to pull the transmission codes and replace the solenoid and I bet your troubles will be fixed. If you want to pull the code yourself and aren't sure how to do it, you can give me a call and I will talk you thru it. It will not show up on the OBD2 scan.

#6 bstone


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Posted 18 February 2011 - 01:49 PM

http://www.ultimates...nsmission codes

#7 Mike104


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Posted 19 February 2011 - 10:48 AM

I had an issue with the TC locking and unlocking at cruise and the CEL and ATF Light were the clues to what to do to fix it. Do what others have suggested and get the transmission fault code. That will help you solve your problem. Doing a 'mod' to fix something that is broken may not fix your issue and as Nipper says may cause you even more grief.

Getting the code is free, bring the code back here and they will help you fix it right.

#8 eulogious


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Posted 19 February 2011 - 06:25 PM

Lucky for you I had this EXACT same problem, and I fixed it. The TCU is bad. I would swap out the TCU. I traced all the wiring back, and even dropped the trans pan and replaced the solenoid, and I was having the same problem. So I replaced the TCU, and the problem went away.

Now if you want to just override it, that's easy as well. Find the wire (Connector B33, Pin 5 in the diagrams below) and apply 12+ going to the solenoid. I would of course wire up a relay and a switch, but that should be all you have to do. The solenoid will lockup when it gets 12v+. I don't recommend doing it as it will probably fry the solenoid at some point and make sure you fuse everything properly, but if you don't care about any of that, then have at'er batter! There's my disclaimer.

Posted Image

Posted Image

These pics are of a older legacy TCU, but the wires haven't changed, and these pics were handy. I actually have the complete FSM for a 1995 legacy on my computer, but I really don't want to look for it, so there pics will do. The wires are the same either way.

Personally what I would do is test the resistance of the circuit itself and see if there is a short in the circuit, or if the solenoid actually still works before I would go cutting wires. If you need help with diagnosing your Duty B solenoid, then just ask!

#9 Xanadu62


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Posted 20 February 2011 - 01:57 AM

Thanks Eulogious! I plan on getting a front TT clip and doing a manual swap in the near future, so I'm not that worried about the long term (60k+). The car needs a new rack and pinion, brake calipers, rotors, hub bearings, rear drive shaft, and the only way to get the JDM clutch pedal is to order the clip anyways, so I figure why not knock out everything at once. I do know fron experience that these cars are notoriously tough. Ricearu had a '93 lego wagon that started out as a Hertz rental car, then switched owners until he got it. The thing lasted until 250k+, and the motor still ran strong! The tranny is what died. Once again, thanks man.

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