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Old 06-25-2014, 02:50 PM   #261 (permalink)
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I'm posting this here for reference. Its a great article on how GM's TCC lockup logic has progressed through the years:


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Old 08-23-2014, 01:12 PM   #262 (permalink)
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Originally Posted by Christ View Post
SO you basically want a foot 'clutch' that's a switch instead of a cable or hydraulics... seems legit.
What I was thinking was to wire in two switches. The first to be wired to the throttle valve, so the lock-up disengaged when you lifted your foot. The second would go to the cockpit. The second could be wired in series or parallel, depending upon what control you wanted...
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Old 08-24-2014, 12:22 PM   #263 (permalink)
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Originally Posted by taredog View Post
I have been doing some research on an on demand TC lockup for my Dakota. I'm not quite there yet but have learned some interesting facts.

It appears that if I can find the right wire from the TCM that it applies B+ to the L/R-CC solenoid. I haven't figured out yet if the battery voltage is on the solenoid and the TCM gives it a ground or the TCM actually applies voltage. It does use PWM for partial lockup but PWM is just the amount of time battery voltage is on or off.

It also appears that the 45RFE transmission I have is mechanically the same as the 545RFE, but with a different TCM program. What the 545 program does is provide an additional OD ratio of .67:1 in addition to the current .75:1 ratio.

Yeah, I know, I called BS on this until I researched it a lot. It is a matter of which clutch is engaged in which of the three planetary gear sets. Turns out Jeep has been doing this since late 01 and Dakotas since late 02 or 03. The problem with Dakotas is that the TCM was combined in to the PCM for the 545 so you can't upgrade. The solution, allegedly, is to get a TCM from a late 01 to 04 Grand Cherokee. I have found a couple in salvage (junk to me) yards for less than $100 and am looking in to getting one.

Of course this will only help highway FE. The quest for the on demand TC lock up and eventually controlling the gear selection continues.

If any of you have any info on the 45RFE about TC lockup on demand or controlling the gear selection, please let me know. I have found a lot of data and it's just a matter of analyzing it all.
I realize this thread is older, but regardless I am still interested. I have been scouring the DR wiring diagrams, for the 545RFE and various connections. I believe the L/R solenoid is the one responsible for activating the lockup, but what I am not sure of is if I splice into that wire and put 12v on it, will the computer kick a code and then go into limp mode because it doesn't like the signal it's getting.

My first thought is to take the signal from the PCM and run it through a resistor to ground. Then provide 12v to the solenoid when I want (probably upshifting or steady state 2nd-5th, if the clutch will lock in all 4 gears). Any ideas?

[edit] just found this: http://www.dakota-durango.com/forum/...ad.php?t=66357 looks like the solenoid needs a ground signal.
Originally Posted by orange4boy View Post
All I can say is WOW!

Latest mixed tank fill netted 30.2mpg up from an average of 24. I can hardly believe it but there it is. Also got a record tank distance of 818km/508mi.

That's almost a 26% improvement. It may settle down a bit on the next tank but we will see. I doubt most people would get the same improvement because I live in a very hilly area where the slushbox was labouring up these hills at low speed, high RPM and I could never get into OD. Now I cruise the flats at 30-35 locked up in OD and do most of those hills locked up in 3rd or OD.

30mpg combined! So happy!
This is good return on investment!! Really makes me want to do this.
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Last edited by ECONORAM; 08-24-2014 at 12:39 PM.. Reason: found more info
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Old 08-25-2014, 10:06 AM   #264 (permalink)
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Based on my own (ongoing) experience with having a 545RFE computer control the transmission in my 2000 Dodge Dakota, I can tell you the following:
  • If OD OFF is selected, the torque converter will lock up in 3d gear, as low as 30 MPH.
  • If OD OFF is not selected, the torque converter will not lock up until the truck is going about 48 MPH or so.
  • Also, if OD OFF is not selected, the truck will not go into 5th gear until it reaches about 55 MPH.
  • Since the 545RFE computer does not use the same network physical layer as the rest of the truck, the network bus wires will have to be disconnected going to the transmission computer. You will, of course, lose the shift indicator and the OD OFF indicator; as well as other "enhanced" functionality brought about by networking the computers together. (Honestly, I think that the writers were onto something good, in the re-imagined Battlestar Galactica series, when they described Galactica's various computers as not being networked.)

I have noticed that the truck tends to unlock the torque converter when the throttle is completely closed. This happens a lot more now, with the version 3 aerocap installed, than in the past. This could likely be avoided by sending a spoofed TPS signal to the 545RFE transmission computer, making it think the throttle is open more than it really is.
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ECONORAM (08-25-2014)
Old 08-25-2014, 11:45 AM   #265 (permalink)
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tvago, thanks. I think your truck has a separate trans control module, correct? I don't know a lot about it, but if I'm reading the diagrams right, my truck is an all-in-one setup. I was wondering if I could wire in a "dummy" solenoid to the truck's inputs, and then wire the TCC solenoid to ground. But even that wouldn't work all the time, as the same solenoid used for TC lock also shuttles for reverse and first. (Can't quite follow that logic, but okay). Maybe if I tap the right wires to show when the tranny hits 2nd, I could use that to trigger a relay to ground the solenoid...
Or, I'll just give up and go find a 5- or 6-speed for the truck. :idea:

[edit] found a link with some items that will do the trick, and then some: http://www.powertraincontrolsolution...oduct/TCM2000/
Sigh, like most other things, they aren't cheap. $750 for a controller, $190 for a harness. I can buy a rebuilt 5-speed nv3500 for $800.

Last edited by ECONORAM; 08-25-2014 at 12:50 PM..
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Old 08-25-2014, 03:14 PM   #266 (permalink)
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With my dodge intrepid, I also found that it is not as simple as give it 12v or switch it to ground. The computers are looking at a ton of information to keep everything working, especially since pretty much all chryslers had limp mode, meaning the controllers knew when the trans was broke, but not out of commission. If an electrical guru wants to rig something up great, but id be wary of just wiring in a switch.

I remember finding information where a guy had made a circuit that would alleviate a shifting problem on an early '90s chrysler if I remember correctly. I may have found it on allpar.com? Its been a while. Might be useful.

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Old 08-26-2014, 02:06 PM   #267 (permalink)
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I think I might have found it: Chrysler, Plymouth, and Dodge Four-Speed Automatic Transmission Torque Converter Disabling
I see the same wires in the harness for the 545RFE; it could work. Too bad work is preventing me from having time to try it now.
[edit] the circuit includes a dummy solenoid; hope that is enough to persuade the computer to buy it...

Last edited by ECONORAM; 08-28-2014 at 11:44 AM..
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Old 06-13-2015, 07:41 PM   #268 (permalink)
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Originally Posted by darrylrobida View Post
I owned a 1968 VW bug that had "automatic stick shift"
As near as I could tell, it was a manual transmission that was mated
to a TC. There was no manual clutch. I shifted the transmission
just like a manual transmission. The knob on the stick shift had a sensitive
switch that would make contact whenever you touched the knob.
This switch controlled the TC lockup solenoid.
It was a good and simple set up that always worked perfectly.
I hope you can use this info.
I had a 69 VW bug with the same transmission

It had both a torque converter AND a clutch. The clutch was vacuum operated by a slave and the slave received vacuum from a "honker valve" by the engine. Momentary contact switches surrounded the shifter- when you put your hand on the shifter, the momentary contact switch would complete ground for the honker valve, the honker valve would open, and this would allow vacuum to go to the vacuum clutch slave which would disengage the clutch. You could idle in gear at a complete stop, take off in 2nd gear for increased traction in bad weather, and didnt really have to know how to use a clutch.

It was a pretty ingenious design for the day, but it was damn slow I loved mine but it broke a shift fork and was stuck in reverse- I looked for at least a month trying to find SOMEWHERE that had parts, but couldnt find any. This was back in 2002, so the internet wasnt as robust as it is now. I finally had to give up and install a manual in the car. I still have the transmission though- one of these days im going to rebuild it
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Old 06-13-2015, 08:48 PM   #269 (permalink)
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I wish I could do the opposite on my Mustang. The ability tc disable to lockup would be great

Last edited by Baltothewolf; 06-13-2015 at 09:34 PM..
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Old 06-13-2015, 10:51 PM   #270 (permalink)
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wow ok i need to do this on my corsica.

off to read 26 pages now


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lockup, lockup switch, torque converter

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