Manual TCC Lockup

[DieselSlug]

Recently had a friend purchase a 98 Cummins with a manual TCC lockup switch. I really want to know how to do this with my truck? How do you wire it? What should you tap into? I want it to work stock like it should but when i want to turn it on manually it can be done with a flip of the switch. Is this ok for a transmission with 214k on it? I would have posted in the tranny section but i thought it would get more attention here. I saw one thread on it but it didnt say too much. Thanks!

 

[benjammin]

Here's what I used:

http://blog.heathdiesel.com/2005/11/manual-operation-of-torque-converter.html

 

[DieselSlug]

Thanks!

 

[Matt Bachand]

I really wish I could do this with OBD2.

 

[540s10]

It can be done on obd2 you just power the lockup solenoid, the transmission works the same... however im not convinced doing this is nice at all for the transmission. I figure if your using it while towing and the ecm calls for a 4-3 downshift when you're heavy in the throttle it will go BOOM. The powdered metal gears in these things arent designed for that kinda shock load.

 

[ak diesel driver]

biggest prob is it throws codes in obd2. IIRC Edzzed has it tho

 

[JiFaire]

You can't do this with OBD-II ... the TCC solenoid accepts only PWM signal, shorting the line to ground will force limp mode and error code.

If you want to lock an OBD-II tranny, you need a BD Autolok or BD Torquelok (can't remember which)... but that is what Edzzed has.

 

[540s10]

you just take the solenoid out and let it dangle in the pan, and put a new one in and wire it to the switch. 94-95 trucks also have a PWM solenoid.

its just the ECU detects that its fully grounded (100%) lockup, says FU, cuz its not what it told it to do and goes limp.

although this eliminates any automatic control.

 

[Diesel -T]

Recall gmctd explaining a few years ago that the sensitve unlock was built into the obd2,s to prevent hollow trans output shaft from twisting off, or something to that effect.

 

[dhjunkie]

Copied from the torq-lock owners manual.
The difference between the AutoLoc and TorqLoc is that the AutoLoc automatically
controls the TCC lock up signal once it receives a power signal from the exhaust
brake switch and the TorqLoc has a manual position, automatic (or AutoLoc
position), and an Off position.
So, in comparing between the AutoLoc and the TorqLoc, the TorqLoc will force the
convertor clutch to lock up & the AutoLoc will only hold an already locked up
convertor clutch. When you ask for an overdrive to third gear shift, the TorqLoc
doesn’t wait for the computer to lock up the clutch, it sends its own signal to the
convertor clutch, and as long as you are A) above the set speed and B) the
transmission is hydraulically correct, [throttle pressure is applied], the TorqLoc will
force a lock up.
The AutoLoc cannot force a lock up, but can only hold it on deceleration. The
Chrysler transmission does not lock up in third gear, unless the overdrive is turned
off. Also, the Chrysler transmission won’t allow an overdrive to third gear downshift
if the TC clutch is locked up. This holds true not matter what system you are using
to hold the TC locked up.
While driving with the overdrive turned off, and the AutoLoc is turned on, the
transmission shifts from first to second to third, and then locks up.
Anytime after the lock up has occurred and you take your foot off the accelerator,
the AutoLoc will turn the exhaust brake on and hold the torque convertor clutch
locked until about 25mph when it will then turn off the torque convertor clutch.
When driving on the freeway in overdrive, the torque convertor clutch will be locked
up and the AutoLoc turned on, if you release the throttle the AutoLoc will apply the
brake and hold the TC clutch lock up.
To increase the amount of retarding horsepower, turn off the overdrive and the
AutoLoc will sense this signal and cut the signal that’s holding the torque convertor
clutch applied, the transmission will then downshift into third gear. At this point you
should apply throttle pressure until the factory computer says everything is okay and
locks up the torque convertor clutch.
As soon as this happens you should remove throttle pressure and the AutoLoc will
turn the exhaust brake on and keep the torque convertor clutch applied until you get
down to about the 25mph mark. The set speed is adjustable, one can set it for a
higher mph, so you don’t have to worry about remembering to turn off the overdrive
or lower if one has 4:10 gears.
Now suppose you’re driving along, overdrive is on, the AutoLoc is on and you need
to make a stop or slow down, but don’t need the extra retarding horsepower of third
gear or you don’t have time to wait for the downshift, applying throttle and waiting
for lockup, (this would all take about 4-6 seconds) and you don’t want the shuddering that would occur when you have a locked up torque convertor clutch &
you’re going to be doing less than 35 mph in overdrive.
You can do any of the four following actions to cancel out the system: 1) turn off the
AutoLoc switch, 2) turn off the overdrive, 3) lightly step on the throttle pedal, or 4)
pull the gearshift lever down into second gear. Turning off the overdrive or the
AutoLoc are the best of the four options.
Now enters the TorqLoc, it should only be used under light throttle applications. No
matter whose torque convertor you are using, the converter clutch has only so much
holding power & if you exceed this you will start to slip the clutch, thereby starting
the demise of your convertor clutch.
An example of when to use the TorqLoc position would be when you are on a
winding road where you are on and off the throttle a great deal and you don’t want
to keep locking and unlocking the convertor clutch. The TorqLoc will hold the
convertor clutch locked up, preventing that from happening.
You must keep in mind, while doing this, that if you apply too much throttle
pressure, especially at the lower rpm band, you may start to slip the convertor
clutch. A general rule of thumb when holding the convertor clutch locked up is no more that 1 lb of boost for every 100 rpm of engine speed.

 

[Michaeljp86]

The TCC lockup I did on my truck throws codes if you flip it in 2nd gear. Or maybe its first gear. It goes into limp mode and you only have 2nd gear until you clear the codes.

 

[JiFaire]

Probably 2nd gear... the 92-93 trucks weren't supposed to lock in 2nd, so your TCM freaks out when it sees that.

Wire a 3-pole switch so that it has 3 positions:

- ground to TCC Solenoid wire (TCM wire unhooked) (Forces Lock)
- TCC Solenoid hooked up to TCM (normal) (TCM-Controlled)
- TCC solenoid unhooked, TCM unhooked (Forces unlocked)

If you just put ground to the wire and left the TCM in the circuit, then the TCM will see the grounded solenoid in 2nd and code.

 

[Michaeljp86]

Probably 2nd gear... the 92-93 trucks weren't supposed to lock in 2nd, so your TCM freaks out when it sees that.

Wire a 3-pole switch so that it has 3 positions:

- ground to TCC Solenoid wire (TCM wire unhooked) (Forces Lock)
- TCC Solenoid hooked up to TCM (normal) (TCM-Controlled)
- TCC solenoid unhooked, TCM unhooked (Forces unlocked)

If you just put ground to the wire and left the TCM in the circuit, then the TCM will see the grounded solenoid in 2nd and code.

Wouldnt just flipping the switch back to the TCC hooked to TCM make it unlock?

My switch is either the TCC hooked to TCM or TCC to ground.

 

[JiFaire]

Not sure, Michael... that's just the way I had mine set up.

A friend of mine didn't break the circuit - just spliced in a switched ground to that line, and when he grounded the circuit, he coded. We fixed it by wiring a 3-pole switch in like mine. Thought perhaps that might be your issue.

Does your TCC Lock work fine in 3rd and OD? That's really the only placed I used mine, anyway - and only when I was pulling a trailer.

 

[Michaeljp86]

The TCC works fine. After I hooked it up and was playing around with it and I think it was in 2nd when I locked it. After I flipped it off it wouldnt shift out of 3rd. I cleared the codes and everything was fine. It doesnt set a code in 3rd gear.

 

[DieselSlug]

I just see that 300 or so rpm difference as enough power to make it up some of the hills here. My truck rarely tows and if i did i wouldnt use the manual lockup at all. SOmetimes i feel i have better grunt with my foot on the brake a little to unlock the converter than in 3rd and unlocked at 2800 rpm. I havent doen it yet but am really serious about doing it.

 

[Michaeljp86]

I did the TCC switch to save fuel while towing.

 

[JiFaire]

I did it to:

- generate less heat while towing (made a HUGE difference to my coolant temps)
- get some engine braking while towing (let me stay off the brakes more)
- generate some big torque in 3rd at the right speed ranges (where it would normally kick in/out a lot)

Saved some fuel - bonus!

 

[Matt Bachand]

I just see that 300 or so rpm difference as enough power to make it up some of the hills here. My truck rarely tows and if i did i wouldnt use the manual lockup at all. SOmetimes i feel i have better grunt with my foot on the brake a little to unlock the converter than in 3rd and unlocked at 2800 rpm. I havent doen it yet but am really serious about doing it.

To me its the opposite, I feel 2500rpm unlocked feels less torque than 2000 locked. I watch my rpms climb, the second 3rd locks up, the SPeedo starts to climb.

OUr situations will change dramatically once we get a little KOJO up in there from what i've been told.... The reflash will add power where there wasn't before, and with a little TCC tweak, I can see how the truck will drive completely different.

 

[DieselSlug]

To me its the opposite, I feel 2500rpm unlocked feels less torque than 2000 locked. I watch my rpms climb, the second 3rd locks up, the SPeedo starts to climb.

OUr situations will change dramatically once we get a little KOJO up in there from what i've been told.... The reflash will add power where there wasn't before, and with a little TCC tweak, I can see how the truck will drive completely different.

Yeah, i cant remember what i was thinking typing this, i wrote it backwords. I also feel more power or grunt with it locked in. So when you lock up the converter should it be done @ 45mph and above due to strain put on the transmission?