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So i read we cant hardwire a tow haul/performance, apparently it goes throught the bcm then tells the tcm. Oh well, was worth asking lol.
i was looking at hptuners forum and someone had asked about it a while back, i tried making changes to the setting for pattern z and did not notice any changes. I got tired of trying different setting wasting fuel. But new info makes me want to start experimenting again, specially now that i have to retune my car for more boost.
If you are savvy with microcontrollers you could rig up a CAN communication controller and send out the values that the TCM is expecting to utilize the alternative maps and tap to shift.
So i read we cant hardwire a tow haul/performance, apparently it goes throught the bcm then tells the tcm.
Correct, that is done through serial data but the output to the transmission is not. Some solenoids are duty cycled but that is easy to do. I have been pondering a couple different ideas.
I can either set up a switch board in the shifter to manually shift through the manual ranges or what i would rather do is replace the shift interlock button with a 2 way toggle to upshift and down shift. I am also looking for some paddle shifters I can get to fit the Cobalt then build a circuit to do the same.
Correct, that is done through serial data but the output to the transmission is not. Some solenoids are duty cycled but that is easy to do. I have been pondering a couple different ideas.
I can either set up a switch board in the shifter to manually shift through the manual ranges or what i would rather do is replace the shift interlock button with a 2 way toggle to upshift and down shift. I am also looking for some paddle shifters I can get to fit the Cobalt then build a circuit to do the same.
I also have thought about doing a stand alone controller or bypass controller. However with what I know now, CAN would be the cleanest.
Food for thought, If you back door the trans, while the TCM is online, to shift or what not, be prepared for limp mode to activate. At minimum you will see DTC's.
If you are savvy with microcontrollers you could rig up a CAN communication controller and send out the values that the TCM is expecting to utilize the alternative maps and tap to shift.
I personally have had this done on a 6L45.
Sounds interesting, unfortunately im only beginning to learn how the controllers communicate. I have been using hptuners for about a year and have learned so much but still have a ways to go to further understand how canbus signals work. Any info on how you did it for your 6L45?
HGT: i think you could use the paddle shifters for the malibu, or g6, maybe even corvette since their steering wheels are the same as ours. I was researching tap shift a while back and found the paddle shifters on the g6 wired to the shifter, as the shifter has tap shift. Though i believe tap shift is initiated through the BCM as well the signal is sent to TCM
Sounds interesting, unfortunately im only beginning to learn how the controllers communicate. I have been using hptuners for about a year and have learned so much but still have a ways to go to further understand how canbus signals work. Any info on how you did it for your 6L45?
This shows how to make a CAN "sniffer" which basically allows you to monitor what is being sent across the CAN Bus. The process I used to back door the TAP shifting is pretty straight forward.
The hardest part will be finding a vehicle that has the same TCM and Trans, which I believe is the G6. You connect to the can bus, monitor what is flowing through, and actuate the TAP shifting. This will send a shift command through the CAN bus which will be a new PGN (parameter group number, think data) from what was previously available on the bus. Record this value! Do the same for TAP shifting the opposite way. You should check all of the gears that they do not have different PGN's associated with them. I.E. check that the up shift from 1->2 PGN on the bus is not different than the PGN for up shifting from 3->4.
Once these values are captured it becomes relatively easy. You can setup a momentary button circuit for the arduino or micro controller, one for each shift direction ( tap up or down). Program it so that when you press the corresponding button, the arduino transmits the shift up or shift down command onto the CAN bus. When this happens, the TCM will receive the request and shift via TAPS. If you want the option of paddle shifters and tap shifting, parallel wire the paddles to the momentary buttons.
HGT: i think you could use the paddle shifters for the malibu, or g6, maybe even corvette since their steering wheels are the same as ours. I was researching tap shift a while back and found the paddle shifters on the g6 wired to the shifter, as the shifter has tap shift. Though i believe tap shift is initiated through the BCM as well the signal is sent to TCM
This is correct, the tap shift buttons and paddle shifters are wired directly to the BCM. The BCM interprets their actuation and then send out the corresponding shift message over CAN to the TCM.
The paddle shift receives system voltage from the BCM and runs it through 8250 ohms of resistance to the TCM to hold the current gear. Tap up goes through 2887 ohms momentarily and tap down goes through 1269 ohms momentarily.
The Cobalt system is very generic.... 1-2, 2-3 solenoids grounded and PC solenoid duty cycled. It would be best to setup a manual shift at the shifter and use HP tuner to set the individual pressures. Here's a YouTube video of someone that did it with 3 home style light switches.... Funny to see and watch
This shows how to make a CAN "sniffer" which basically allows you to monitor what is being sent across the CAN Bus. The process I used to back door the TAP shifting is pretty straight forward.
The hardest part will be finding a vehicle that has the same TCM and Trans, which I believe is the G6. You connect to the can bus, monitor what is flowing through, and actuate the TAP shifting. This will send a shift command through the CAN bus which will be a new PGN (parameter group number, think data) from what was previously available on the bus. Record this value! Do the same for TAP shifting the opposite way. You should check all of the gears that they do not have different PGN's associated with them. I.E. check that the up shift from 1->2 PGN on the bus is not different than the PGN for up shifting from 3->4.
Once these values are captured it becomes relatively easy. You can setup a momentary button circuit for the arduino or micro controller, one for each shift direction ( tap up or down). Program it so that when you press the corresponding button, the arduino transmits the shift up or shift down command onto the CAN bus. When this happens, the TCM will receive the request and shift via TAPS. If you want the option of paddle shifters and tap shifting, parallel wire the paddles to the momentary buttons.
Wow, sounds like quite the fun little project. Ill order one of those can analyzers when theyre available. I already have an obd2 connector from my hptuners unit (my dog bit the cable and tore it in two, had to buy a new one). Thanks for the info! If i understood correctly, i need to find a vehicle wirh the same trans and controller with tap shift and hook up the can analyzer to it, correct?
The Cobalt system is very generic.... 1-2, 2-3 solenoids grounded and PC solenoid duty cycled. It would be best to setup a manual shift at the shifter and use HP tuner to set the individual pressures. Here's a YouTube video of someone that did it with 3 home style light switches.... Funny to see and watch
that is pretty cool, i did not think you could even use an electronicly controlled trans without a tcm. I would like to figure out a tow haul mode like on trucks, to use different shift speeds and pressures
Here's a circuit that I did quick to manually shift the 4T45E. Let HP tuners control the times and pressures. It could be a redesigned PRNDL switch or a new board at either the shifter or trans.
Would have to turn off the trans diagnostics.
So it is possible to manual shift the 4t45e in the cobalt. A user in the hptuners forum was asking about trying to hold the car in 1st gear but the car still shifts to second. This would be a great solution for that.
I also found a pdf file that explains how the tap shift works on an 04 malibu classic with the 4t45e. Has a diagram of the wiring and info on how it works too.
Wow, sounds like quite the fun little project. Ill order one of those can analyzers when theyre available. I already have an obd2 connector from my hptuners unit (my dog bit the cable and tore it in two, had to buy a new one). Thanks for the info! If i understood correctly, i need to find a vehicle wirh the same trans and controller with tap shift and hook up the can analyzer to it, correct?
That is correct. The beauty of this approach, the BCM / TCM / ECM still work seamlessly and all of your diagnostics / fault reactions are still valid in the event issues arise down the road.
If I remember right, he was going into a hidden lower gear but the tcm was still making the final decision. If the TCM is physically removed from the equation and still shifting it is internally shifting by oil pressure overriding a spring pressure which would require the valve body to be altered.
I also found a pdf file that explains how the tap shift works on an 04 malibu classic with the 4t45e. Has a diagram of the wiring and info on how it works too.
I'd like to see that.
Here's the 04 Malibu Trans schematic condensed as much as I could.
Everything non related removed. There is no TCM. There not listing the PCM as a VCM either.
It would be MUCH easier to build a seperate logic circuit for paddle shifting the Cobalt. Personally I would set it up to manual shift from the floor.
The Malibu diagram above has the TAP enable going to the BCM so the dash indicator comes on and the PCM does all the shift commands. I have 2 cars with paddles and I find it difficult to use while turning. Neither has a rally car turning radius tight enough to use without difficulty. I will work on a shift box setup. I haven't checked with HP Tuners to see if the 1-2 shift is commanded at WOT or overridden. I'm at 6725 on my 1-2 and that may be the default WOT override.
An even more condensed version. Same resistance values as the new Malibu's, just no TCM
The paddle shift receives system voltage from the BCM and runs it through 8250 ohms of resistance to the TCM to hold the current gear. Tap up goes through 2887 ohms momentarily and tap down goes through 1269 ohms momentarily.
I have only driven 2 cars with paddles, a turbo 325i BMW and a 2013 genesis. The genesis automaticly shifted when i got to a certain RPM. The BMW though hit redline twice before it shifted automaticly. Not sure how the gm cars work but id be certain they wont let you hold the gear for too long as to prevemt damage to the engine or trans.
on another note, have you seen the tables for an hhr ss with the 4t45e? Their settings are way different than other cars i have seen with the 4t45e. The torque converter also has different settings. Not sure if they improve performance. Was going to try those settings on my car and see how they feel.
I have only driven 2 cars with paddles, a turbo 325i BMW and a 2013 genesis. The genesis automaticly shifted when i got to a certain RPM. The BMW though hit redline twice before it shifted automaticly. Not sure how the gm cars work but id be certain they wont let you hold the gear for too long as to prevemt damage to the engine or trans.
on another note, have you seen the tables for an hhr ss with the 4t45e? Their settings are way different than other cars i have seen with the 4t45e. The torque converter also has different settings. Not sure if they improve performance. Was going to try those settings on my car and see how they feel.
4T45e in the HHR SS Auto was a LNF 2.0L Turbo at like 240Hp, would be a good look over for boosting LE5 4T45e combos.
4T45e in the HHR SS Auto was a LNF 2.0L Turbo at like 240Hp, would be a good look over for boosting LE5 4T45e combos.
yes, thats the reason i decided to look at one. I was just wondering of it uses different tables for competition mode. Then maybe i can use your info to get tap shift working to get a form of competition mode working like the tow haul button on trucks.
I was just wondering of it uses different tables for competition mode.
The HHR Transmission wiring schematic is identical to the Cobalt. It doesn't show any additional modes.
Does the HHR actually have a performance mode other than the no lift shift for the Manual?
07-21-2017, 08:41 AM
