trugertha1
Full Access Member
im thinking about doing this , what are the pros and cons.. and how do i do it? thanx
torque converter lockup mod
- Thread starter trugertha1
- Start date
LCAM-01XA
Full Access Member
Wanna fry another PCM, I see 
The advantage of the lockup mod lies in a "flaw" in the factory PCM programming - the way your truck is now, when you let off the throttle the converter unlocks, which means very little engine braking and when you go down some 8% grades like all the time you really learn to appreciate engine braking. The disadvantage is that with a manual switch the converter will not unlock when you step on the brakes (unless you wire in a SPDT relay and run it off the BOO switch), and it will never unlock when you go slower than 30mph or when you stomp on the throttle hard. So really tis all your call - if you can live with locking and unlocking it manually, then go for it, but if you can't pay enough attention to the converter in all sorts of driving situations then maybe you shouldn't do it...
The advantage of the lockup mod lies in a "flaw" in the factory PCM programming - the way your truck is now, when you let off the throttle the converter unlocks, which means very little engine braking and when you go down some 8% grades like all the time you really learn to appreciate engine braking. The disadvantage is that with a manual switch the converter will not unlock when you step on the brakes (unless you wire in a SPDT relay and run it off the BOO switch), and it will never unlock when you go slower than 30mph or when you stomp on the throttle hard. So really tis all your call - if you can live with locking and unlocking it manually, then go for it, but if you can't pay enough attention to the converter in all sorts of driving situations then maybe you shouldn't do it...
sootman73
Registered User
after a month it becomes instinct. i love the engine braking plus it helps produce less heat in the trans(not that that matters to me as i have an AC condenser for cooler) and you can use less rpms to get tothe same speed. that bugged me the most was waiting for the TC to catch up to the engine rpm speed without the truck moving as fast as it should.
trugertha1
Full Access Member
haha yes, i picked up 2 more pcms this week haha...yes id like it mostly for the braking as im goin to be looking at getting a bigger trailer probly a fifth wheel (exhaust brake is pricey) also read on another thread that it can up mpg? is this true?. and id like to be able to have stock setup and well as manual setup..guess dpdt?
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LCAM-01XA
Full Access Member
SPDT (5-pole) relay will be needed for the brakes either way you wire it up, tis just a safety feature I came up with for my truck and I absolutely love it so far. Then for the auto/lock thing you'll need a DPDT (6-pole) switch along with a 22k-ohm resistor. I'll draw you a wiring diagram one of these days, I'm just a bit swamped with work here...
trugertha1
Full Access Member
i would greatly apprieciate that, no rush tho. just laid off and bored haha
Fozz
Full Access Member
I just did this mod this week, and depending what you want to do determines which switch you need. I'm leaving tomorrow for the weekend, will be my first trip with the mod, but when I return, I can do a write up as well. You really only need a spst switch, but you want an on-center off- on (three postion switch). I got a three position dpdt switch because I wired light indications too. A double pole double throw (dpdt) switch is electrically two switches, activated by a single physical switch (throw).
LCAM-01XA
Full Access Member
Fozz, you do need a DPDT switch, you also need the 22k resistor - if you looked through the lockup mod threads you probably noticed some folks experiencing limp mode after they trip the switch and converter gets locked when the PCM wants it open. The resistor is used to feed alternate signal to the PCM whenever the lockup is under manual control (be it open or locked), it essentially creates a "dummy converter" so the PCM is happy and proceeds to do its thing, while you do your thing with the switch.
international
Drownin' in diesel
I'd love to see that diagram too!
oldmisterbill
Grumpy Old Man
I have driven many-many heavily loaded towing miles using a TC lock up switch. I feel this is one of the most important mods for longevity of the transmission-considering torque convertor clutch wear,and maintaining lower operating temps.
My biggest complaint with how I set mine up is that I have to remember to manualy unlock it to return it to the Computer control modual. So at a stop light if I forget it the truck would shudder reminding me to hit the switch.(only did this a couple times). My preference would to switch to lock up and have the TC stay locked 100% till I slowed down to the speed that the PCM normally unlock the TC & allow it to take over till I was back above that speed till I get above that speed again (somewhere around 30 MPH )then at my option I could reset the Lock up or it could automaticly return to full lock up at my discrestion.I would not want the TC to unlock every time I touched the brake pedal as it does it the normal PCM controlled mode,I want the PCM to only interfear when I set the lock up at low speeds then at my descretion I can return from 100% PCM control back to manual control. Hope I made sense and we are on the same page.
Too often when pulling hard another vehicle will slow down causing me to step on the brake pedal in preperation for a qiuck or panic slow down.When I go to resume my speed especially when loaded I would step down more on the throttle to resume speed - causing the TC to lock up under a heavy throttle and in my opinion resulting in what a standard shift would refer to as "slipping the chutch" This cannot be good for the TC clutches. This is the 200 to 300 RPM drop we experience during lockup.
I would love to see a diagram of the inner workings of the PCM.I think there may be other way to simplify the different desires of using a lock up switch. My 2 Bits
My biggest complaint with how I set mine up is that I have to remember to manualy unlock it to return it to the Computer control modual. So at a stop light if I forget it the truck would shudder reminding me to hit the switch.(only did this a couple times). My preference would to switch to lock up and have the TC stay locked 100% till I slowed down to the speed that the PCM normally unlock the TC & allow it to take over till I was back above that speed till I get above that speed again (somewhere around 30 MPH )then at my option I could reset the Lock up or it could automaticly return to full lock up at my discrestion.I would not want the TC to unlock every time I touched the brake pedal as it does it the normal PCM controlled mode,I want the PCM to only interfear when I set the lock up at low speeds then at my descretion I can return from 100% PCM control back to manual control. Hope I made sense and we are on the same page.
Too often when pulling hard another vehicle will slow down causing me to step on the brake pedal in preperation for a qiuck or panic slow down.When I go to resume my speed especially when loaded I would step down more on the throttle to resume speed - causing the TC to lock up under a heavy throttle and in my opinion resulting in what a standard shift would refer to as "slipping the chutch" This cannot be good for the TC clutches. This is the 200 to 300 RPM drop we experience during lockup.
I would love to see a diagram of the inner workings of the PCM.I think there may be other way to simplify the different desires of using a lock up switch. My 2 Bits
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LCAM-01XA
Full Access Member
Bill, I'm pretty sure I'm following you correct, you want a 30mph shutoff speed for the manual TC lockup, without automatic reset when you're up to speed again. This is what I'd love to have too, however figuring out something like that is a bit beyond my abilities an knowledge of electric components. Maybe the PCM can be reflashed somehow to accommodate the feature you want, but other than that I think the only way of achieving this would be with an aftermarket controller, IIRC David85 programmed his Bauminator to lock converter over 30mph and unlock it under 30 mph, with no regard of brakes application or throttle signal...
trugertha1
Full Access Member
Bauminator???? is that the aftermarket e4od computer???
LCAM-01XA
Full Access Member
Yeps, tis made Baumann Engineering.
dsblack
Full Access Member
a great system. had it on my 90 can make it do just about anything you want
trugertha1
Full Access Member
ya i was looking at the system online and it looks really good, might just hold off on this and invest in the aftermarket pcm
