The thing I liked least about the Ram TCM was that it downshifted from 5th to easily under heavy load, sending rpm waaay high.
The Ram TCM works pretty good when driven like a responsible, mature adult. But thats kinda hard for me to do sometimes
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| Help understanding how a TCM works http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=85247 |
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| Author: | uncaged [ Fri Sep 09, 2016 3:01 pm ] |
| Post subject: | Help understanding how a TCM works |
Can someone explain how the software/control portion of the TCM works? What functions are permanent or hard coded into the TCM? What functions can be manipulated with tuning? For example, the RAM TCM has higher line pressures. Where is that information stored and controlled? Can a tune overwrite that portion? What part of the TCM does what? |
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| Author: | flash7210 [ Fri Sep 09, 2016 3:55 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
Do you have a way of reading the TCM and make changes to programming? That would be awesome if you did. Sorry, I can't be of any help. GDE figured how to to do it. They probably have the special tools to do it. And I doubt they are willing to share that info. |
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| Author: | uncaged [ Thu Sep 15, 2016 8:16 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
Not sure if I have anything to read it. I've got a DRBIII, VAGCOM, a MPPS cable, and other miscellaneous other electronic gadgetry from projects past. Will any of that work? Either way I'm less inclined to fiddle around with it and wind up bricking the thing than I am sending it to GDE to have them do it. But I really am interested in knowing how it works and what stays with the TCM and what gets overwritten with KJ base code. |
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| Author: | wilco549 [ Fri Sep 16, 2016 11:16 am ] |
| Post subject: | Re: Help understanding how a TCM works |
I know very little about the TCM but I can tell you that Dodge trucks, some Cherokee's and the probably several other models use the same TCM with slightly different programming. I'm running a RAM TCM in mine. So, brick away but I suggest you do it on a more readily available TCM model. |
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| Author: | mass-hole [ Fri Sep 16, 2016 12:45 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
wilco549 wrote: I know very little about the TCM but I can tell you that Dodge trucks, some Cherokee's and the probably several other models use the same TCM with slightly different programming. I'm running a RAM TCM in mine. So, brick away but I suggest you do it on a more readily available TCM model. GDE was able to flash my ram TCM to Pre-F37 Liberty programming but for some reason could not flash it to their custom Eco tune. Before I sent it in they did tell me someone else's Ram TCM did take their programming, mine was just weird. They just send it back to me and I sent them my stock Jeep TCM to get their tune flashed on so now I have the GDE Eco and a pre-F37 spare. Just an FYI in case anyone decides to brick their's and needs a replacement. |
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| Author: | dennyb [ Fri Sep 16, 2016 8:00 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
I swapped my TCM with a 02 gas liberty unit. It started out programmed for the 45rfe (shifted gears 1-4 only. Bought for 45 at LKQ self serve. Drove to GDE IN April. They tuned it with eco trans tune while I waited. Then we put it in and tested on their industrial park road. Then did full torque eco tune with a second test run. |
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| Author: | uncaged [ Fri Sep 16, 2016 9:58 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
So mass-hole, What was the ram TCM like after the pre-F37 flash as compared to the stock ram code? My stock ram TCM is totally hooked up to the ground. Shifting into R or D is immediate and firm with a lurch. As it shifts through gears, it's a stiff, quick shift and I do not want to loose those characteristics. I love spinning the tires at half throttle from a stop. That's how an auto should run. I took my Ram TCM out in anticipation of finding a solution to preventing the over-revving disaster, and put my GDE eco TCM back in and was sorely disappointed by slushboxiness. What I ultimately want is GDE towing tune on the stiffness of the stock Ram TCM. How do I get there? |
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| Author: | flash7210 [ Fri Sep 16, 2016 10:33 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
The thing I liked least about the Ram TCM was that it downshifted from 5th to easily under heavy load, sending rpm waaay high. The Ram TCM works pretty good when driven like a responsible, mature adult. But thats kinda hard for me to do sometimes
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| Author: | mass-hole [ Sat Sep 17, 2016 12:09 am ] |
| Post subject: | Re: Help understanding how a TCM works |
uncaged wrote: So mass-hole, What was the ram TCM like after the pre-F37 flash as compared to the stock ram code? My stock ram TCM is totally hooked up to the ground. Shifting into R or D is immediate and firm with a lurch. As it shifts through gears, it's a stiff, quick shift and I do not want to loose those characteristics. I love spinning the tires at half throttle from a stop. That's how an auto should run. I took my Ram TCM out in anticipation of finding a solution to preventing the over-revving disaster, and put my GDE eco TCM back in and was sorely disappointed by slushboxiness. What I ultimately want is GDE towing tune on the stiffness of the stock Ram TCM. How do I get there? The pre-F37 pretty much feels the same as the post F37 but just has different shift points and TC lockup. Maybe use the resistor from the transgo kit to stiffen up the line pressures in conjunction with the GDE tune? |
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| Author: | mass-hole [ Sat Sep 17, 2016 12:13 am ] |
| Post subject: | Re: Help understanding how a TCM works |
flash7210 wrote: The thing I liked least about the Ram TCM was that it downshifted from 5th to easily under heavy load, sending rpm waaay high. The Ram TCM works pretty good when driven like a responsible, mature adult. But thats kinda hard for me to do sometimes I always had trouble with mine at this one highway on ramp I had to take everyday for work. The ramp was super tight so you could only do 25mph but had to immediately merge into 65mph traffic because the entrance lane turned into an exit lane. Too many times I pushed the throttle slightly too hard trying to get up to 65mph and had it downshift to far and sent the motor to 5k. Of course when that happened it cut fuel and it jeep would just sit there. |
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| Author: | uncaged [ Sun Sep 18, 2016 8:42 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
mass-hole wrote: The pre-F37 pretty much feels the same as the post F37 but just has different shift points and TC lockup. Maybe use the resistor from the transgo kit to stiffen up the line pressures in conjunction with the GDE tune? Did your pre-flashed Ram TCM act like I describe mine acting, very stiff in the shifts? When I put it into D the Jeep lurches. When I put the original CRD TCM in with the GDE tune, you almost can't even tell you shifted from N to D. So did you have a stiff Ram TCM to start, and if so, did it retain the stiffness, or lose it with the flash? |
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| Author: | Sir Sam [ Sun Sep 18, 2016 8:50 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
uncaged wrote: Not sure if I have anything to read it. I've got a DRBIII, VAGCOM, a MPPS cable, and other miscellaneous other electronic gadgetry from projects past. Will any of that work? Either way I'm less inclined to fiddle around with it and wind up bricking the thing than I am sending it to GDE to have them do it. But I really am interested in knowing how it works and what stays with the TCM and what gets overwritten with KJ base code. Interestingly enough the DRBIII lets you see hex address values in the TCM while it is online. It cannot modify anything in the TCM, but it is interesting as a read online function. The DRBIII can write to the TCM for flashing updates. Watching the serial comms during an update might help understand the communication. I suspect it is possible to "tune" the TCM by simple serial read writes to change hex tables, but I don't have the time to really screw with it. wilco549 wrote: I know very little about the TCM but I can tell you that Dodge trucks, some Cherokee's and the probably several other models use the same TCM with slightly different programming. I'm running a RAM TCM in mine. So, brick away but I suggest you do it on a more readily available TCM model. NO CHEROKEE's use the same TCM as the KJ. |
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| Author: | uncaged [ Mon Oct 03, 2016 9:39 pm ] |
| Post subject: | Re: Help understanding how a TCM works |
Sam, thanks for inspiring me to dust off the DRBIII. After hooking it up, connecting to the RAM TCM and setting some monitors while doing a little drive-around, I may have found something. The Engine RPM reporting from the ECU to the TCM is about *half* of what the Trans input RPM sensor reports. Trans Input sensor and dash tach agree. Monitor Parameter Example: Engine RPM - 780 Input RPM - 1558 Output RPM - 2333 Gear - 5th TCC Full Lock - YES I'll hook up a KJ TCM when I get a chance and run the same monitors and see what it says. Does anyone know what voltage is expected on this K244 line? I've looked in the various SM's and see how to test the wire, but not an expected value related to engine RPM. EDIT: Tonight, I put the KJ TCM back in, and did more testing, using the same monitor, and a voltmeter on the K244 line on pin 6 of the TCM. Firstly, the KJ TCM reported the Engine RPM correctly with relation to the Input Sensor. Monitor: Engine RPM - 1769 Input RPM - 1760 Output RPM - 2640 Gear - 5th TCC Full Lock - YES K244 line TCM pin 6 (brown wire) DC voltage reporting: All VoltsDC: Engine off, key off - .74 Engine off, key on - 10.26 Engine idle - bounce from 6.03 to 6.30 1500 RPM - 6.00 2000 RPM - 5.96 2500 RPM - 5.94 3000 RPM - 5.92 3500 RPM - 5.91 Seems like this may not be the correct monitor for this. For grins, I turned the meter to AC and got a steady 6.54VAC on the same line. Seems like maybe it's pulsing signal. Maybe a crank sensor pulse? |
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