tc lockup
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Senior User
Joined: Sep 2010
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tc lockup
is it possible to wire the torque converter to lock up on a switch?
ascending a 20% or so grade in 2nd doing about 30, i am at around 2500-3000 rpms depending on speed/incline. however going down the same hill, in 2nd gear, i get up to 40 or so before the tach gets to 3000 rpms.
i attribute this to the TC not locking up and was just wondering if there was a way to lock the TC to help control speed downhill better.
i could use 1st gear, but then i end up going a rediculous 15-20 mph at less than 2200 rpms.
truck is an 03 250 with a 5.4 and the 4 speed auto.
to summarize:
i want more engine braking, can i force the TC to lock?
ascending a 20% or so grade in 2nd doing about 30, i am at around 2500-3000 rpms depending on speed/incline. however going down the same hill, in 2nd gear, i get up to 40 or so before the tach gets to 3000 rpms.
i attribute this to the TC not locking up and was just wondering if there was a way to lock the TC to help control speed downhill better.
i could use 1st gear, but then i end up going a rediculous 15-20 mph at less than 2200 rpms.
truck is an 03 250 with a 5.4 and the 4 speed auto.
to summarize:
i want more engine braking, can i force the TC to lock?
Postmaster
Joined: Jun 2008
Posts: 2,564
Likes: 11
From: Wayyy NoCal, USA
Yes. Several folks have explained how.
Here's one:
http://dieselinnovations.com/techfiles/tclockup.pdf
I believe there are even "kits" available to make it easier if you're not a DIY'er.
I did it and installed an LED to tell me when locked. Handy, and I have no regrets.
One thing to keep in mind: You have to remember to turn the switch off.
Letting the truck shift while manually locked is pretty harsh and can be hard on tranny.
Hitting the brakes while manually locked can trip a trouble code and illuminate the CEL. I didn't know that, and the first time the CEL lit up (while towing heavy!) it kinda concerned me. Luckily I had my SCT programmer with me and could scan the code and reset CEL.
Here's one:
http://dieselinnovations.com/techfiles/tclockup.pdf
I believe there are even "kits" available to make it easier if you're not a DIY'er.
I did it and installed an LED to tell me when locked. Handy, and I have no regrets.
One thing to keep in mind: You have to remember to turn the switch off.
Letting the truck shift while manually locked is pretty harsh and can be hard on tranny.
Hitting the brakes while manually locked can trip a trouble code and illuminate the CEL. I didn't know that, and the first time the CEL lit up (while towing heavy!) it kinda concerned me. Luckily I had my SCT programmer with me and could scan the code and reset CEL.
Cargo Master
Joined: Apr 2006
Posts: 3,215
Likes: 8
From: WV
Subscribing... this seems like a useful mod, but I'm unsure about when its safe to have it locked manually. Maybe someone can shed some more light on this?
For instance, if I'm driving up a mountain with lots of curves, when I come out of a turn, it downshifts and I can feel it lockup and it gains speed quickly. Then, when I slow for the next turn, I guess it upshifts & unlocks and I have to downshift-lockup-gain speed all over again.
On some of the turns I can maintain enough speed to keep it locked and it still pulls hard without downshifting.
I just don't know enough about how it works to be confident enough to utilize a mod like this.
For instance, if I'm driving up a mountain with lots of curves, when I come out of a turn, it downshifts and I can feel it lockup and it gains speed quickly. Then, when I slow for the next turn, I guess it upshifts & unlocks and I have to downshift-lockup-gain speed all over again.
On some of the turns I can maintain enough speed to keep it locked and it still pulls hard without downshifting.
I just don't know enough about how it works to be confident enough to utilize a mod like this.
Laughing Gas
Joined: Jul 2010
Posts: 1,025
Likes: 1
From: Clearwater Fl.
Yes. Several folks have explained how.
Here's one:
http://dieselinnovations.com/techfiles/tclockup.pdf
I believe there are even "kits" available to make it easier if you're not a DIY'er.
I did it and installed an LED to tell me when locked. Handy, and I have no regrets.
One thing to keep in mind: You have to remember to turn the switch off.
Letting the truck shift while manually locked is pretty harsh and can be hard on tranny.
Hitting the brakes while manually locked can trip a trouble code and illuminate the CEL. I didn't know that, and the first time the CEL lit up (while towing heavy!) it kinda concerned me. Luckily I had my SCT programmer with me and could scan the code and reset CEL.
Here's one:
http://dieselinnovations.com/techfiles/tclockup.pdf
I believe there are even "kits" available to make it easier if you're not a DIY'er.
I did it and installed an LED to tell me when locked. Handy, and I have no regrets.
One thing to keep in mind: You have to remember to turn the switch off.
Letting the truck shift while manually locked is pretty harsh and can be hard on tranny.
Hitting the brakes while manually locked can trip a trouble code and illuminate the CEL. I didn't know that, and the first time the CEL lit up (while towing heavy!) it kinda concerned me. Luckily I had my SCT programmer with me and could scan the code and reset CEL.
EDIT. It is working for me now.
Senior User
Joined: May 2010
Posts: 364
Likes: 0
From: mt.prospect
My converter locks even when I'm a wot.Always has.around 3200rpm
I would love to do this mod just so the converter would stay locked when I'm on the highway and let off for 1 second then press
the gas the converter releases then locks again. Dumb programming! My bmw stays locked downhill uphill wot. It's the best programmed auto I've ever driven.
I would love to do this mod just so the converter would stay locked when I'm on the highway and let off for 1 second then press
the gas the converter releases then locks again. Dumb programming! My bmw stays locked downhill uphill wot. It's the best programmed auto I've ever driven.
Thread Starter
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Senior User
Joined: Sep 2010
Posts: 352
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i guess its the electronics in the transmission.
my previous car had a 700r4 4 speed auto, and the tC lockup was electronically activated, but based on hydraulic pressure.
i had a switch so that it would force lockup when the switch was on, except 1st gear of course.
when the trans shifted, it would automatically unlock for a fraction of a second because the hydraulic pressure to the TC lockup solenoid dipped when the pressure was rediverted to the gear changing mechanisms.
i could literally drive up any mountain in 3rd gear locked with no trouble, but that was a 2900 lb car with 400 lb-ft of torque at 1200-3000 rpms lol.
my previous car had a 700r4 4 speed auto, and the tC lockup was electronically activated, but based on hydraulic pressure.
i had a switch so that it would force lockup when the switch was on, except 1st gear of course.
when the trans shifted, it would automatically unlock for a fraction of a second because the hydraulic pressure to the TC lockup solenoid dipped when the pressure was rediverted to the gear changing mechanisms.
i could literally drive up any mountain in 3rd gear locked with no trouble, but that was a 2900 lb car with 400 lb-ft of torque at 1200-3000 rpms lol.
