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How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

This is a discussion on How do I wire a "manual" switch to lock torque converter on my 1991 Suburban?? within the Technical / Maintenance forums, part of the General Discussion category; Years ago we wire a toggle switch to manually lock the torque converter. The problem is, when towing, my torque ...

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    How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??


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    Years ago we wire a toggle switch to manually lock the torque converter.

    The problem is, when towing, my torque converter is constantly switching on and off depending an throttle position.

    I want to be able to manually lock the converter while I am steady on the hi-way.

    Seems like we used to tie a wire into the harness of the ECM and switch it to ground.

    Do you guys know which wire???

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Should be Tan-Blk, pin J at the Trans and A4 at the PCM. The schematic I'm looking at also shows a splice with one leg running straight to the ALDL. You may be able to do it all from the ALDL. Check for a Tan-Blk at pin F of the ALDL. Pin A, Blk-Wht, of the ALDL should be a ground.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    waltv... thanks!! That worked great.

    I tested it and it does not lock up till 2nd gear.

    Is it OK to drive like this?? In other words is it OK to take off with converter unlocked, and then soon at is shifts to 2nd the converter is locked and locked until it shifts to 3rd??

    I did this and it worked GREAT! Just wanna make sure I am not hurting anything!

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    It may wear your TC or 2-4 band/input drum more quickly. Tbh, I'm not sure of the long term effects.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    to be sure, you may want to contact transbuilderguy

    2005 2500HD>Duramax>EFI Live DSP5 by Punisher Performance>FASS Platinum LP>AFE Turbo MP>EGR Blocked>PCV Rerouted>Mild audio setup>4" Exhaust>Alligator Performance Race Fuel Valve>Edge Insight CTS

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Thanks for the info. I tested the Suburban with my trailer in tow. It seems to be doing fine. I can always mount the switch in a way that I can easily switch it on once I am on the hiway and cruising steady state.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    1+ Agree with Duramaximizer. Would love transbuilderguy's thoughts on running TC locked in overdrive-second.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    all i know is you dont want the torque converter locked up during shifts.
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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Quote Originally Posted by NEUMANNZZ View Post
    all i know is you dont want the torque converter locked up during shifts.
    I was pulling a 24' Enclosed trailer at about 8,000# and it shifted very smooth with the TC locked. It only does the 2-3 shift locked because the ECM blocks it from locking in 1st. I don't pull in OD.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Sorry, for some reason I was thinking this was a 4L60 in this, but its a 4L80 correct? So, my comment earlier about the 2-4 band/input drum doesn't apply.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Quote Originally Posted by waltv View Post
    Sorry, for some reason I was thinking this was a 4L60 in this, but its a 4L80 correct? So, my comment earlier about the 2-4 band/input drum doesn't apply.
    No it is an old school 700 r4. I built the transmission with improved clutches, an RV shift kit and an RV torque converter. It is basically the same as a 4l60 but without electronic controlled shifting.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    I talked to a friend of mine who owns a transmission repair shop (The same guy who helped me build/beef up this transmission). He said there would be NO long term ill effects of letting the transmission shift from 2-3 with the converter locked. He said the only issue would be if you were accelrating hard, you would lose the torque multiplication that a torque converter has. He said if one is accelerating in a normal manner, lock up is fine. He even used an example that mid 90's Ford AOD transmissions lock when they shift to third and remain locked while they shift to 4th.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Glad the wiring colors worked up. Mitchell only listed a 4l80 for the 91 Suburban.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Quote Originally Posted by waltv View Post
    Glad the wiring colors worked up. Mitchell only listed a 4l80 for the 91 Suburban.
    Yes, I think they put a 4L80 in the 2500 Suburbans. Mine is a 1500.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    you do ot want the trans to lock during the shifts ifit does you will be replacing the input drum...the best way to rig a lockup is to get a pressure switch and drill and tap it into the servo cover...hot wire the tcc solenoid and have the pressure switch control the ground side of the system when 4th gear comes in and pressure is applied it will close the pressure switch and complete the circuit giving you lockup in 4th.

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Quote Originally Posted by transbuilderguy View Post
    you do ot want the trans to lock during the shifts ifit does you will be replacing the input drum...the best way to rig a lockup is to get a pressure switch and drill and tap it into the servo cover...hot wire the tcc solenoid and have the pressure switch control the ground side of the system when 4th gear comes in and pressure is applied it will close the pressure switch and complete the circuit giving you lockup in 4th.
    Yep I agree!!! I found out the leaving it locked during shifts sucks!! Besides you lose the torque multiplication that the torque converter makes. I wait until I am at highway speed and then lock it up. Works fine that way.

    In fact, I just got back from a 150 mile trip to the race track and back with 24' trailer, race car, tools, generator, golf cart, and other junk. Used the switch the whole time.

    What I need now is some 4.11 gears. These 3.42 are killing me!!!


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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    if you hook up a pressur switch like i said in the post you wont have to flip any switches (: it will lock automatically as soon as 4th hits

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    Thats the problem. I don't tow in 4th. I need lock up in 3rd as well. Can I put a pressure switch in the 3rd gear pressure area?

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    Re: How do I wire a "manual" switch to lock torque converter on my 1991 Suburban??

    nah no way to do that without getting reall electrically involved lol it could be done off the pressure manifold switch but I wouldnt reccomend doing it.

 

 

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