I know from towing that if I slow down and let the tranny downshift to 2nd while driving in "D", the torque converter will still lock up on its own. Will the torqe converter lock up if you manually select "2" or "1"?? I haven't tried it towing yet, but I drove around the neighborhood a little bit in 2 and never could get the converter to lock. Did I just not give it enough time or does it not work that way??

 

The TC will not lock up in manual 1st. It will lock in 2nd gear.


Steve

 

If you had custom tuning you would get that baby to lock up for you !!

 

I've had my TC lock in 2nd gear with the lever on '2'... I was going up a very steep hill in my neighborhood and was going around 30mph. I had the pedal to the floor and it bogged to 20 as I got to the top! I really needed 1st gear to get up that hill (or unlocked 2nd), but since I had manually pulled it to '2', it was locked and I had cars right on my ***, so I didn't want to drop it to '1' or let off the gas....

Now, when I'm taking a different (flat) route, I can get it to lock in 2nd with the lever in '2', but I've got to get the speed over 40mph (in a 35mph zone).....

For the most part, my TC does not lock in 'city' driving and towing... The most my trans temp has gotten is 210* in these conditions, so I'm not too worried about it...

I get it to lock all the time on the long grades in 2nd and putting the lever in '2'. I then pull those grades at 50-55mph and my trans temp is around 195* (on a 90*+ day too!)

Gotta just 'learn' your truck and adjust to what it wants to do... I don't take that 'big hill' route in my neighborhood anymore....

1st gear will never lock, no matter what you do, but it should lock in 2nd, and I find it does it at the lower speeds when the lever is in '2' and either a lot of pedal, or hardly any pedal. Not in between....

Mitch

 

Thanks Mitch, huge help and what I wanted (needed) to hear. It's always been relatively easy to lock in second or third when in "D", but just never tried it in manual yet.

I don't know what the difference is as I think we have our temp gauges mounted in the same place, but I can easily, and relatively quickly get my temp up to 210* with the converter unlocked. I'm sure it would keep going. I made a short journey through town yesterday with my trailer and even though I got kinda lucky with the lights, I can get my converter to lock in 3rd gear at anything above 40mph ever since I installed 4.10 gears....they rock.

 

OK, towed the trailer up to the lake this weekend and she didn't like the hills. Had one bad spot where I was trying to learn what the truck wants. Took 4-friggin-EVER to get the tranny to lock in 2nd. Tranny got up to 235* unlocked. Every time it would lock (in 2nd) someone or something (turn, light, etc) would screw up my momentum. I was getting worried until I finally made the top and reached the destination. Let the truck idle for quite a while to cool off the tranny.

I'm just wondering why it tool soooo long to lock in 2nd like that?? Once it did that first time, then I could control the back and fourth, but the temp was getting hot having to slow down and speed up like that. Oh well...I'll figure it out.

 

I've found that actually 'flooring' the pedal while the gear lever is in '2' will cause the TC to lock, even if it's bogging the engine down!

When I was cruising up a hill in 2nd and noticed that my trans temp was rising, I knew right away that I was still unlocked. I tried to let off, but nothing. Then I just kept pushing it harder until I felt it lock and then I was able to keep it locked by keeping my speed over 45.. I started to actually gain speed, so I could let off the gas some as I neared the top. My trans temp settled to 195* just before the top.

Just some more 'learning' you have to do to find out what your trans can handle. You probably have the 4r70, so I don't know if it's 'programmed' differently then my e4od?? Maybe??

235* for a couple of minutes is not going to be a 'bad' thing.... It's when it runs at a high temp constantly, that bad things will happen...

Mitch

 

The only way the PCM has to know what is being asked of the running gear is the TPS position vs loading and the govenor/rpm also gets into the act and some timing goes into the logic decision on what the trans does.
The TC lock up even responds to accelerator and brakeing actions.
It is hard to predict what will happen under any given set of conditions because there are too many inputs that contribute to the results.

 

Im planning to put a switch in mine pretty soon. It annoys me when it locks up in the city and I wan't control of it when towing. Here is the basic plan, maybe somebody can add something.

Im guessing the circuit operates on 5v logic, Im going run a 3 position dial type switch. Position 1 will be full computer control. Position 2 will ground the circuit (which I think will force it unlocked). Position 3 will be a little bit trickier, I will have to set up some resistors in a 12v line to get a voltage drop down to 5v, which will then be sent though the circuit which should force the converter locked.

One problem may be the limp mode in the computer, if its not getting feedback from the trans it could force it in to that mode. Thats just a guess, im not sure what critera the comp uses to determine that stuff. Thats an easy enough fix with custom tune though.

 

Nope, it is controlled off of ground. Positive voltage is constant to the solenoids. Ground is switched.

Darrin

 

WOW!!! That seems like a heeluva chore to tackle...let us know how that turns out??