Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Freezing the Slushbox. Torque Converter on-demand lockup switch.

taredog · 10-23-2009, 11:21 PM

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.

10-23-2009, 11:21 PM	#134 (permalink)
taredog EcoModding Lurker Join Date: Jun 2009 Location: Phoenix Posts: 87 pickup - '01 Dodge Dakota Quad Cab 4x4 Sport 90 day: 16.35 mpg (US) Focus - '16 Ford Focus SE 90 day: 31.46 mpg (US) Thanks: 0 Thanked 4 Times in 3 Posts	45RFE transmission 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.